topics / مواضيع: ANESTHESIA Hadzic's Peripheral Nerve Blocks Hadzic parte 06

ANESTHESIA Hadzic's Peripheral Nerve Blocks Hadzic parte 06

Equipment

A standard regional anesthesia tray is prepared with the following equipment:

Sterile towels and gauze packs

Two 20-mL syringes containing local anesthetic

Sterile gloves, marking pen, and surface electrode

A 3- to 5-mL syringe plus 25-gauge needle with local anesthetic for skin infiltration

Peripheral nerve stimulator

Catheter kit (including an 8- to 10-cm large-gauge stimulating needle and catheter).

Kits come in two varieties based on catheter construction: nonstimulating (conventional) and

stimulating catheters. During the placement of a conventional nonstimulating catheter, the stimulating

needle is first advanced until appropriate twitches are obtained. Then 5–10 mL of local anesthetic or

other injectate (e.g., D5W) is then injected to “open up” a space for the catheter to advance freely

without resistance. The catheter is then threaded through the needle until approximately 3 to 5 cm is

protruding beyond the tip of the needle. The needle is then withdrawn, the catheter secured, and the

remaining local anesthetic injected via the catheter. Stimulating catheters are insulated and have a

filament or core that transmits current to a bare metal tip. After obtaining twitches with the needle, the

catheter is advanced with the nerve stimulator connected until the sought motor response is obtained.

This method requires that no conducting solution (i.e., local anesthetic, saline) be injected through the

needle prior to catheter advancement, or difficulty obtaining a motor response will result.

Landmarks and Patient Positioning

The patient is positioned in the prone position with the feet extending beyond the table to facilitate

monitoring of foot or toe responses to nerve stimulation.

The landmarks for a continuous popliteal block are essentially the same as those for the singleinjection technique (Figure 20.1-4). These include the following:

. Popliteal fossa crease

. Tendon of the biceps femoris muscle (laterally)

. Tendons of the semitendinosus and semimembranosus muscles (medially)

The needle insertion site is marked 7 cm proximal to the popliteal fossa crease and between the

tendons of the biceps femoris and semitendinosus muscles (Figure 20.1-5).

Technique

The continuous popliteal block technique is similar to the single-injection technique. With the patient

in the prone position, infiltrate the skin with local anesthetic using a 25-gauge needle at an injection

site 7 cm above the popliteal fossa crease and between the tendons of biceps femoris and

semitendinosus muscles. An 8- to 10-cm needle connected to the nerve stimulator (1.5 mA current) is

inserted at the midpoint between the tendons of the biceps femoris and semitendinosus muscles.

Advance the block needle slowly in a slightly cranial direction while observing the patient for

rhythmic plantar or dorsiflexion of the foot or toes. After appropriate twitches are noted, continue

manipulating the needle until the desired response is seen or felt using a current ≤0.5 mA. The

catheter should be advanced no more than 5 cm beyond the needle tip (Figure 20.1-9). The needle is

then withdrawn back to skin level while advancing the catheter simultaneously to prevent inadvertent

removal of the catheter.

FIGURE 20.1-9. Needle direction and insertion of the catheter for continuous popliteal sciatic block.

The catheter is inserted 3–5 cm beyond the needle tip.

The catheter is checked for inadvertent intravascular placement and secured using an adhesive skin

preparation, followed by application of a clear dressing. The infusion port should be clearly marked

“continuous nerve block.”

TIP

When insertion of the catheter proves difficult, lowering the angle of the needle or rotating the needle

may facilitate the catheter insertion.

Continuous Infusion

Continuous infusion is initiated after injection of an initial bolus of local anesthetic through the

catheter or needle. For this purpose, we routinely use 0.2% ropivacaine 15 to 20 mL. Diluted

bupivacaine or levobupivacaine are also suitable but may result in greater degree of motor blockade.

The infusion is maintained at 5 to 10 mL/h with a 5-mL patient-controlled bolus hourly.

Complications and How to Avoid Them

Complications following a popliteal block are uncommon. Table 20.1-2 lists some general and

specific instructions on possible complications and how to avoid them.

TABLE 20.1-2 Complications of Popliteal Sciatic Nerve Block and Preventive Techniques

SUGGESTED READING

Benzon HT, Kim C, Benzon HP, et al. Correlation between evoked motor response of the sciatic nerve

and sensory blockade. Anesthesiology. 1997;87:547-552.

Borgeat A, Blumenthal S, Karovic D, Delbos A, Vienne P. Clinical evaluation of a modified posterior

anatomical approach to performing the popliteal block. Reg Anesth Pain Med. 2004;29:290-296.

Borgeat A, Blumenthal S, Lambert M, Theodorou P, Vienne P. The feasibility and complications of the

continuous popliteal nerve block: a 1001-case survey. Anesth Analg. 2006;103:229-233.

Capdevila X, Dadure C, Bringuier S, et al. Effect of patient-controlled perineural analgesia on

rehabilitation and pain after ambulatory orthopedic surgery: a multicenter randomized trial.

Anesthesiology. 2006;105:566-573.

Cappelleri G, Aldegheri G, Ruggieri F, Mamo D, Fanelli G, Casati A. Minimum effective anesthetic

concentration (MEAC) for sciatic nerve block: subgluteus and popliteal approaches. Can J Anaesth.

2007;54:283-289.

Compere V, Rey N, Baert O, et al. Major complications after 400 continuous popliteal sciatic nerve

blocks for post-operative analgesia. Acta Anaesthesiol Scand. 2009;53:339-345.

i Benedetto P, Casati A, Bertini L, Fanelli G, Chelly JE. Postoperative analgesia with continuous

sciatic nerve block after foot surgery: a prospective, randomized comparison between the popliteal

and subgluteal approaches. Anesth Analg. 2002;94:996-1000.

Ekatodramis G, Nadig M, Blumenthal S, Borgeat A. Continuous popliteal sciatic nerve block. How to

be sure the catheter works? Acta Anaesthesiol Scand. 2004;48:1342-1343.

Eurin M, Beloeil H, Zetlaoui PJ. A medial approach for a continuous sciatic block in the popliteal fossa

[in French]. Can J Anaesth. 2006;53:1165-1166.

ernandez-Guisasola J. Popliteal block as an alternative to Labat’s approach. Anesth Analg.

2002;95:252-253.

ernandez-Guisasola J, Andueza A, Burgos E, et al. A comparison of 0.5% ropivacaine and 1%

mepivacaine for sciatic nerve block in the popliteal fossa. Acta Anaesthesiol Scand. 2001;45:967-

970.

ournier R, Weber A, Gamulin Z. Posterior labat vs. lateral popliteal sciatic block: posterior sciatic

block has quicker onset and shorter duration of anaesthesia. Acta Anaesthesiol Scand. 2005;49:683-

686.

Gouverneur JM. Sciatic nerve block in the popliteal fossa with atraumatic needles and nerve

stimulation. Acta Anaesthesiol Belg. 1985;36:391-399.

Guntz E, Herman P, Debizet E, Delhaye D, Coulic V, Sosnowski M. Sciatic nerve block in the popliteal

fossa: description of a new medial approach. Can J Anaesth. 2004;51:817-820.

Hadžić A, Vloka JD. A comparison of the posterior versus lateral approaches to the block of the sciatic

nerve in the popliteal fossa. Anesthesiology. 1998;88:1480-1486.

Hadžić A, Vloka JD, Singson R, Santos AC, Thys DM. A comparison of intertendinous and classical

approaches to popliteal nerve block using magnetic resonance imaging simulation. Anesth Analg.

2002;94:1321-1324.

feld BM, Loland VJ, Gerancher JC, et al. The effects of varying local anesthetic concentration and

volume on continuous popliteal sciatic nerve blocks: a dual-center, randomized, controlled study.

Anesth Analg. 2008;107:701-707.

feld BM, Morey TE, Wang RD, Enneking FK. Continuous popliteal sciatic nerve block for

postoperative pain control at home: a randomized, double-blinded, placebo-controlled study.

Anesthesiology. 2002;97:959-965.

feld BM, Thannikary LJ, Morey TE, Vander Griend RA, Enneking FK. Popliteal sciatic perineural

local anesthetic infusion: a comparison of three dosing regimens for postoperative analgesia.

Anesthesiology. 2004;101:970-977.

Kilpatrick AW, Coventry DM, Todd JG. A comparison of two approaches to sciatic nerve block.

Anaesthesia. 1992;47:155-157.

March X, Pineda O, Garcia MM, Carames D, Villalonga A. The posterior approach to the sciatic nerve

in the popliteal fossa: a comparison of single- versus double-injection technique. Anesth Analg.

2006;103:1571-1573.

Moayeri N, Groen GJ. Differences in quantitative architecture of sciatic nerve may explain differences

in potential vulnerability to nerve injury, onset time, and minimum effective anesthetic volume.

Anesthesiology. 2009;111:1128-1134.

Nader A, Kendall MC, Candido KD, Benzon H, McCarthy RJ. A randomized comparison of a modified

intertendinous and classic posterior approach to popliteal sciatic nerve block. Anesth Analg.

2009;108:359-363.

Navas AM. Stimulating catheters in continuous popliteal block. Anesth Analg. 2006;102:1594; author

reply 1594-1595.

almisani S, Ronconi P, De Blasi RA, Arcioni R. Lateral or posterior popliteal approach for sciatic

nerve block: difference is related to the anatomy. Anesth Analg. 2007;105:286.

aqueron X, Narchi P, Mazoit JX, Singelyn F, Benichou A, Macaire P. A randomized, observerblinded determination of the median effective volume of local anesthetic required to anesthetize the

sciatic nerve in the popliteal fossa for stimulating and nonstimulating perineural catheters. Reg Anesth

Pain Med. 2009;34:290-295.

Rodriguez J, Taboada M, Carceller J, Lagunilla J, Barcena M, Alvarez J. Stimulating popliteal

catheters for postoperative analgesia after hallux valgus repair. Anesth Analg. 2006;102:258-262.

Rorie DK, Byer DE, Nelson DO, Sittipong R, Johnson KA. Assessment of block of the sciatic nerve in

the popliteal fossa. Anesth Analg. 1980;59:371-376.

ingelyn FJ, Aye F, Gouverneur JM. Continuous popliteal sciatic nerve block: an original technique to

provide postoperative analgesia after foot surgery. Anesth Analg. 1997;84:383-386.

underland S. The sciatic nerve and its tibial and common peroneal divisions: anatomical features. In:

Sunderland S, ed. Nerves and Nerve Injuries. Edinburgh, UK: E&S Livingstone; 1968.

uresh S, Simion C, Wyers M, Swanson M, Jennings M, Iyer A. Anatomical location of the bifurcation

of the sciatic nerve in the posterior thigh in infants and children: a formula derived from MRI imaging

for nerve localization. Reg Anesth Pain Med. 2007;32:351-353.

Taboada M, Rodriguez J, Alvarez J, Cortés J, Gude F, Atanassoff PG. Sciatic nerve block via posterior

Labat approach is more efficient than lateral popliteal approach using a double-injection technique: a

prospective, randomized comparison. Anesthesiology. 2004;101:138-142.

Taboada M, Rodriguez J, Bermudez M, et al. A “new” automated bolus technique for continuous

popliteal block: a prospective, randomized comparison with a continuous infusion technique. Anesth

Analg. 2008;107:1433-1437.

Taboada M, Rodriguez J, Bermudez M, et al. Comparison of continuous infusion versus automated

bolus for postoperative patient-controlled analgesia with popliteal sciatic nerve catheters.

Anesthesiology. 2009;110:150-154.

Tran D, Clemente A, Finlayson RJ. A review of approaches and techniques for lower extremity nerve

blocks. Can J Anaesth. 2007;54:922-934.

Vloka JD, Hadžić A, April E, Thys DM. The division of the sciatic nerve in the popliteal fossa:

anatomical implications for popliteal nerve blockade. Anesth Analg. 2001;92:215-217.

Vloka JD, Hadžić A, Koorn R, Thys D. Supine approach to the sciatic nerve in the popliteal fossa. Can

J Anaesth. 1996;43:964-967.

Vloka JD, Hadžić A, Lesser JB, et al. A common epineural sheath for the nerves in the popliteal fossa

and its possible implications for sciatic nerve block. Anesth Analg. 1997;84:387-390.

Vloka JD, Hadžić A, Mulcare R, Lesser JB, Koorn R, Thys DM. Combined popliteal and posterior

cutaneous nerve of the thigh blocks for short saphenous vein stripping in outpatients: an alternative to

spinal anesthesia. J Clin Anesth. 1997;9:618-622.

White PF, Issioui T, Skrivanek GD, Early JS, Wakefield C. The use of a continuous popliteal sciatic

nerve block after surgery involving the foot and ankle: does it improve the quality of recovery?

Anesth Analg. 2003;97:1303-1309.

aric D, Boysen K, Christiansen J, Haastrup U, Kofoed H, Rawal N. Continuous popliteal sciatic nerve

block for outpatient foot surgery—a randomized, controlled trial. Acta Anaesthesiol Scand.

2004;48:337-341.

PART 2: LATERAL APPROACH

General Considerations

The lateral approach to a popliteal blockade is similar to the intertendinous block in many aspects.

The main difference is that the technique involves placement of the needle from the lateral aspect of

the leg, therefore obviating the need to position the patient in the prone position. Nerve stimulation

principles, volume requirements, and block onset time are the same. The block is well suited for

surgery on the calf, Achilles tendon, ankle, and foot. It also provides adequate analgesia for a calf

tourniquet.

Functional Anatomy

The sciatic nerve consists of two separate nerve trunks, the tibial and common peroneal nerves

(Figure 20.2-1). A common epineural sheath envelops these two nerves at their outset in the pelvis.

As the sciatic nerve descends toward the knee, the two components eventually diverge in the popliteal

fossa, giving rise to the tibial and common peroneal nerves. This division of the sciatic nerve usually

occurs 5–7 cm proximal to the popliteal fossa crease.

FIGURE 20.2-1. Anatomy of the popliteal fossa crease. tibial nerve. common peroneal nerve

before its division. epineural sheath of the common sciatic nerve. tendon of semitendinosus and

semimembranous. bicep femoris tendon.

Distribution of Blockade

The lateral approach to popliteal block also results in anesthesia of the entire distal two thirds of the

lower extremity with the exception of the skin on the medial aspect of the leg (Figure 20.2-2).

Cutaneous innervation of the medial leg below the knee is provided by the saphenous nerve, the

terminal extension of the femoral nerve. Depending on the level of surgery, the addition of a

saphenous nerve block may be required for complete surgical anesthesia.

FIGURE 20.2-2. Sensory distribution of anesthesia accomplished with popliteal sciatic block. All

shaded areas except medial aspect of the leg (blue, saphenous nerve) are anesthetized with the

popliteal block.

Single-Injection Popliteal Block (Lateral Approach)

Equipment

A standard regional anesthesia tray is prepared with the following equipment:

Sterile towels and gauze packs

Two 20-mL syringes containing local anesthetic

A 3- to 5-mL syringe plus 25-gauge needle with local anesthetic for skin infiltration

A 10-cm, 21-gauge short-bevel insulated stimulating needle

Peripheral nerve stimulator

Sterile gloves; marking pen

Landmarks and Patient Positioning

The patient is in the supine position. The foot on the side to be blocked should be positioned so that

the motor response of the foot or toes can be easily observed (Figure 20.2-3). This is best achieved

by placing the leg on a footrest with the heel and the foot protruding beyond the footrest. This

positioning allows for easy visualization of foot twitches during nerve localization. The foot should

form a 90° angle to the horizontal plane of the table.

FIGURE 20.2-3. Maneuver to accentuate landmarks for popliteal sciatic block. The patient is asked

to flex the leg at the knee, which accentuates the popliteal fossa and hamstring muscles.

Landmarks for the lateral approach to a popliteal block include the following (Figure 20.2-4 and

20.2-5):

. Popliteal fossa crease

. Vastus lateralis muscle

. Biceps femoris muscle

FIGURE 20.2-4. Popliteal fossa is marked with the knee flexed.

FIGURE 20.2-5. The main landmark for popliteal sciatic block is in the groove between the vastus

lateralis and the biceps femoris muscles .

The needle insertion site is marked in the groove between the vastus lateralis and biceps femoris

muscles 7-8 cm above the popliteal fossa crease. Note that the lateral femoral epicondyle is another

landmark that can be used with this technique. It is easily palpated on the lateral aspect of the knee 1

cm cephalad to the popliteal fossa crease (Figures 20.2-6 and 20.2-7).

FIGURE 20.2-6. Needle insertion site is labeled at 7 cm proximal to the popliteal fossa crease in the

groove between the vastus lateralis and bicep femoris muscles.

FIGURE 20.2-7. A needle insertion point for lateral approach sciatic popliteal block.

TIP

In patients with an atrophic biceps femoris muscle (e.g., prolonged immobility), the iliotibial

aponeurosis can prove to be a more consistent landmark). In this case, the needle insertion site is in

the groove between the vastus lateralis and the iliotibial tract.

Maneuvers to Facilitate Landmark Identification

Landmarks can be better appreciated using the following steps:

Lifting the foot off the table accentuates the biceps femoris and vastus lateralis muscles, and helps the

recognition of the groove between the two muscles.

The groove between the vastus lateralis and biceps femoris can be located by firmly pressing the

fingers of the palpating hand against the adipose tissue in the groove approximately 8 cm above the

popliteal fossa crease.

Technique

The operator should be seated facing the side to be blocked. The height of the patient’s bed is

adjusted to allow for a more ergonomic position and greater precision during block placement. This

position also allows the operator simultaneously to monitor both the patient and the responses to

nerve stimulation.

The site of estimated needle insertion is prepared with an antiseptic solution and infiltrated with

local anesthetic using a 25-gauge needle. It is useful to infiltrate the skin along a line rather than raise

a single skin wheal. This allows needle reinsertion at a different site when necessary without the need

to anesthetize the skin again.

A 10-cm, 21-gauge needle is inserted in a horizontal plane perpendicular to the long axis of the leg

between the vastus lateralis and biceps femoris muscles (Figure 20.2-8), and it is advanced to

contact the femur. Contact with the femur is important because it provides information about the depth

of the nerve (typically 1–2 cm beyond the skin to femur distance) and about the angle at which the

needle must be redirected posteriorly to stimulate the nerve (Figure 20.2-9). The current intensity is

initially set at 1.5 mA. With the fingers of the palpating hand firmly pressed and immobile in the

groove, the needle is withdrawn to the skin level, redirected 30° below the horizontal plane, and

advanced toward the nerve.

FIGURE 20.2-8 Needle insertion for lateral approach to popliteal block.

FIGURE 20.2-9. Needle insertion strategy for lateral approach to popliteal sciatic block. (A) needle

is first inserted to contact femur. (B) After contact with the femur, the needle is withdrawn back to the

skin and redirected 30° posteriorly to local the sciatic nerve. Note the needle passage through the

biceps femoris muscle before entering the popliteal fossa crease. This explains why local bicep

femoris muscle twitch is often obtained during needle advancement. 1 - Semimembranosussemitendinosus muscles, 2 - Biceps Femoris, 3 - Femur, 4 - Popliteal artery and vein, 5 - Common

peroneal nerve, 6 - TIbial nerve

GOAL

The ultimate goal of nerve stimulation is to obtain visible or palpable twitches of the foot or toes

at a current of 0.2–0.5 mA.

TIPS

The needle passes through the biceps femoris muscle, often resulting in local twitches of this muscle

during needle advancement. Cessation of the local twitches of the biceps muscle should prompt

slower needle advancement because this signifies that the needle is in the popliteal fossa and in close

proximity to the sciatic nerve.

When stimulation of the sciatic nerve is not obtained within 2 cm after cessation of the biceps femoris

twitches; the needle is probably not in plane with the nerves and should not be advanced further

because of the risk of puncturing the popliteal vessels.

After initial stimulation of the sciatic nerve is obtained, the stimulating current is gradually

decreased until twitches are still seen or felt at 0.2–0.5 mA. This typically occurs at a depth of 5–7

cm. At this point, the needle should be stabilized and, after aspiration test for blood, 30–40 mL of

local anesthetic is injected slowly.

Troubleshooting

When the sciatic nerve is not localized on the first needle pass, the needle is withdrawn to the skin

level and the following algorithm is used:

. Ensure that the nerve stimulator is functional, properly connected to the patient and to the needle, and

set to deliver the current of desired intensity.

. Ensure that the leg is not externally rotated at the hip joint and that the foot forms a 90° angle to the

horizontal plane of the table. A deviation from this angle changes the relationship of the sciatic nerve

to the femur and the biceps femoris muscle.

. Mentally visualize the plane of the initial needle insertion and redirect the needle in a slightly

posterior direction (5–10° posterior angulation).

. If step 3 fails, withdraw the needle and reinsert it with an additional 5–10° posterior redirection.

. Failure to obtain a foot response to nerve stimulation should prompt reassessment of the landmarks

and leg position. In addition, the stimulating current should be increased to 2 mA.

TIPS

When motor response can be elicited only with current of ≥0.5 mA, tibial nerve response (Figure

20.2-10) may be associated with a higher success rate of anesthesia of both divisions of the nerve.

Isolated twitches of the calf muscles should not be accepted as reliable signs because they can be the

result of stimulation of the sciatic nerve branches to the calf muscles that may be outside the sciatic

nerve sheath.

FIGURE 20.2-10. Motor responses of the foot obtained with stimulation of the sciatic nerve in the

popliteal fossa. Stimulation of the tibial nerve results in plantar flexion and inversion of the foot.

Stimulation of the common peroneal nerve results in dorsi flexion and inversion of the foot.

Table 20.2-1 lists the common responses that can occur during block placement using a nerve

stimulator and the proper course of action needed to obtain twitches of the foot.

TABLE 20.2-1 Some Common Responses to Nerve Stimulation and Course of Action

Block Dynamics and Perioperative Management

This technique may be associated with patient discomfort because the needle transverses the biceps

femoris muscle, and adequate sedation and analgesia are necessary. Administration of midazolam (2–

4 mg intravenously) and a short-acting narcotic (alfentanil 250–to 750 g) ensures patient comfort and

prevents patient movement during needle advancement. Inadequate premedication can make it difficult

to interpret the response to nerve stimulation because of patient movement during needle

advancement. A typical onset time for this block is 15–30 minutes, depending on the type,

concentration, and volume of local anesthetic used. The first signs of onset of the blockade are usually

a report by the patient that the foot “feels different” or there is an inability to wiggle their toes. With

this block, sensory anesthesia of the skin is often the last to develop. Inadequate skin anesthesia

despite an apparently timely onset of the blockade is common, and it can take up to 30 minutes to

develop. Local infiltration by the surgeon at the site of the incision is often all that is needed to allow

the surgery to proceed.

Continuous Popliteal Block (Lateral Approach)

The technique is similar to the single-injection except that slight angulation of the needle cephalad is

necessary to facilitate threading of the catheter. Securing and maintaining the catheter are easy and

convenient with this technique. A lateral popliteal block is suitable for surgery and postoperative

pain management in patients undergoing a wide variety of lower leg, foot, and ankle surgeries.

Equipment

A standard regional anesthesia tray is prepared with the following equipment:

Sterile towels and gauze packs

Two 20-mL syringes containing local anesthetic

Sterile gloves, marking pen, and surface electrode

A 3- to 5-mL syringe plus 25-gauge needle with local anesthetic for skin infiltration

Peripheral nerve stimulator

Catheter kit (including an 8- to 10-cm 18–19 gauge stimulating needle and catheter)

Either nonstimulating (conventional) or stimulating catheters can be used. During the placement of

a conventional non-stimulating catheter, the stimulating needle is advanced until appropriate twitches

are obtained. Then 5–10 mL of local anesthetic or other injectate (e.g., D5W) is then injected to

“open up” a space for the catheter to advance freely without resistance. The catheter is threaded

through the needle until approximately 3–5 cm is protruding beyond the tip of the needle. The needle

is withdrawn, the catheter secured, and the remaining local anesthetic injected via the catheter. With

stimulating catheters, after obtaining desired motor response with stimulation through the needle, the

catheter is advanced with the nerve stimulator connected until the anesthesiologist is satisfied with the

quality of the motor response. If the response is lost, the catheter can be withdrawn until it reappears

and the catheter readvanced. This method requires that no conducting solution be injected through the

needle (i.e., local anesthetic, saline) prior to catheter advancement, or difficulty obtaining a motor

response will result.

Landmarks and Patient Positioning

The patient is positioned in the supine position with the feet extending beyond the table to facilitate

monitoring of foot or toe responses to nerve stimulation.

The landmarks for a continuous popliteal block with the lateral approach are essentially the same

as for the single-injection technique and include the following:

. Popliteal fossa crease

. Vastus lateralis

. Biceps femoris

The needle insertion site is marked at 8 cm proximal to the popliteal fossa crease in the groove

between the vastus lateralis and biceps femoris.

Technique

The continuous popliteal block technique is similar to the single-injection technique. The patient is in

the supine position. Using a 25-gauge needle, infiltrate the skin with local anesthetic at the injection

site 7–8 cm proximal to the popliteal crease in the groove between the biceps femoris and vastus

lateralis muscles. An 8- to 10-cm needle with a Tuohy-style tip for a continuous nerve block is

connected to the nerve stimulator (1.5 mA) and inserted to contact the femur (Figure 20.2-11). A

slight cephalad orientation to the needle with the opening facing proximally will aid in catheter

threading. Once the femur is contacted, the needle is withdrawn to the skin level and redirected in a

slightly posterior direction 30°. Then it is advanced slowly while observing the patient for plantar

flexion or dorsiflexion of the foot or toes. After obtaining the appropriate twitches, continue

manipulating the needle until the desired response is still seen or felt using a current of 0.2–0.5 mA.

The catheter should be advanced no more than 5 cm beyond the needle tip. The needle is withdrawn

back to the skin level, and the catheter advanced simultaneously to prevent inadvertent removal of the

catheter.

FIGURE 20.2-11. Catheter insertion technique for popliteal sciatic block. Technique is similar to

that of the single-injection technique. Catheter is inserted 3–5 cm beyond the needle tip.

The catheter is checked for inadvertent intravascular placement and secured to the lateral thigh

using an adhesive skin preparation such as benzoin, followed by application of a clear dressing. The

infusion port should be clearly marked “continuous nerve block.”

TIPS

With a popliteal catheter, a response at 0.5–1.0 mA should be accepted as long as the motor response

is specific and clearly seen or felt.

A very small (e.g., 1 mm) movement of the needle often results in a change in the motor response from

that of the tibial nerve (plantar flexion of the foot) to that of the common peroneal nerve (dorsiflexion

of the foot). This indicates an intimate needle to nerve relationship at a level before divergence of the

sciatic nerve.

When catheter insertion proves difficult, rotate the needle slightly and try reinserting it again. When

these maneuvers do not facilitate insertion of the catheter, angle the needle in a cephalad direction

before reattempting to insert the catheter. With this maneuver, care should be taken not to dislodge the

needle.

Continuous Infusion

Continuous infusion is initiated after an initial bolus of dilute local anesthetic is administered through

the catheter or needle. For this purpose, we routinely use 0.2% ropivacaine 15–20 mL. Diluted

bupivacaine or levobupivacaine are suitable but can result in additional motor blockade. The infusion

is maintained at 5 mL/h with 5-mL/h patient-controlled regional analgesia.

Complications and How to Avoid Them

Table 20.2-2 provides specific instructions on some complications and how to avoid them.

TABLE 20.2-2 Complications of Popliteal Block Through the Lateral Approach and Preventive

Techniques

TIPS

Breakthrough pain in patients undergoing a continuous infusion is always managed by administering a

bolus of local anesthetic. Simply increasing the rate of infusion is not adequate.

When the bolus injection through the catheter fails to result in blockade after 30 minutes, the catheter

should be considered dislodged and should be removed.

All patients with continuous nerve block infusion should be prescribed an alternative pain

management protocol because incomplete analgesia and/or catheter dislodgment can occur.

SUGGESTED READING

Single-Injection Femoral Nerve Block

Allen HW, Liu SS, Ware PD, Nairn CS, Owens BD. Peripheral nerve blocks improve analgesia after

total knee replacement surgery. Anesth Analg. 1998;87:93-97.

Beaulieu P, Babin D, Hemmerling T. The pharmacodynamics of ropivacaine and bupivacaine in

combined sciatic and femoral nerve blocks for total knee arthroplasty. Anesth Analg. 2006;103:768-

774.

Biboulet P, Morau D, Aubas P, Bringuier-Branchereau S, Capdevila X. Postoperative analgesia after

total-hip arthroplasty: comparison of intravenous patient-controlled analgesia with morphine and

single injection of femoral nerve or psoas compartment block. a prospective, randomized, doubleblind study. Reg Anesth Pain Med. 2004;29:102-109.

e Lima ESR, Correa CH, Henriques MD, de Oliveira CB, Nunes TA, Gomez RS. Single-injection

femoral nerve block with 0.25% ropivacaine or 0.25% bupivacaine for postoperative analgesia after

total knee replacement or anterior cruciate ligament reconstruction. J Clin Anesth. 2008;20:521-527.

Eledjam JJ, Cuvillon P, Capdevila X, et al. Postoperative analgesia by femoral nerve block with

ropivacaine 0.2% after major knee surgery: continuous versus patient-controlled techniques. Reg

Anesth Pain Med. 2002;27:604-611.

owler SJ, Symons J, Sabato S, Myles PS. Epidural analgesia compared with peripheral nerve

blockade after major knee surgery: a systematic review and meta-analysis of randomized trials. Br J

Anaesth. 2008;100:154-164.

Hadžić; A, Vloka JD, Kuroda MM, Koorn R, Birnbach DJ. The practice of peripheral nerve blocks in

the United States: a national survey [p2e comments]. Reg Anesth Pain Med. 1998;23:241-246.

skandar H, Benard A, Ruel-Raymond J, Cochard G, Manaud B. Femoral block provides superior

analgesia compared with intra-articular ropivacaine after anterior cruciate ligament reconstruction.

Reg Anesth Pain Med. 2003;28:29-32.

ansen TK, Miller BE, Arretche N, Pellegrini JE. Will the addition of a sciatic nerve block to a femoral

nerve block provide better pain control following anterior cruciate ligament repair surgery? AANA J.

2009;77:213-218.

ochum D, O’Neill T, Jabbour H, Diarra PD, Cuignet-Pourel E, Bouaziz H. Evaluation of femoral nerve

blockade following inguinal paravascular block of Winnie: are there still lessons to be learnt?

Anaesthesia. 2005;60:974-977.

ohnson TW. Will the addition of sciatic nerve block to a femoral nerve block provide better pain

control following anterior cruciate ligament repair surgery? AANA J. 2009;77:417.

Kardash K, Hickey D, Tessler MJ, Payne S, Zukor D, Velly AM. Obturator versus femoral nerve block

for analgesia after total knee arthroplasty. Anesth Analg. 2007;105:853-858.

Lang SA, Yip RW, Chang PC, Gerard MA. The femoral 3-in-1 block revisited. J Clin Anesth.

1993;5:292-296.

Macalou D, Trueck S, Meuret P, et al. Postoperative analgesia after total knee replacement: the effect of

an obturator nerve block added to the femoral 3-in-1 nerve block. Anesth Analg. 2004;99:251-254.

Madej TH, Ellis FR, Halsall PJ. Evaluation of “3 in 1” lumbar plexus block in patients having muscle

biopsy. Br J Anaesth. 1989;62:515-517.

Marhofer P, Nasel C, Sitzwohl C, Kapral S. Magnetic resonance imaging of the distribution of local

anesthetic during the three-in-one block. Anesth Analg. 2000;90:119-124.

Martin F, Martinez V, Mazoit JX, et al. Antiinflammatory effect of peripheral nerve blocks after knee

surgery: clinical and biologic evaluation. Anesthesiology. 2008;109:484-490.

Montes FR, Zarate E, Grueso R, et al. Comparison of spinal anesthesia with combined sciatic-femoral

nerve block for outpatient knee arthroscopy. J Clin Anesth. 2008;20:415-420.

Mulroy MF, Larkin KL, Batra MS, Hodgson PS, Owens BD. Femoral nerve block with 0.25% or 0.5%

bupivacaine improves postoperative analgesia following outpatient arthroscopic anterior cruciate

ligament repair. Reg Anesth Pain Med. 2001;26:24-29.

Ng HP, Cheong KF, Lim A, Lim J, Puhaindran ME. Intraoperative single-shot “3-in-1” femoral nerve

block with ropivacaine 0.25%, ropivacaine 0.5% or bupivacaine 0.25% provides comparable 48-hr

analgesia after unilateral total knee replacement. Can J Anaesth. 2001;48:1102-1108.

Noiseux N, Prieto I, Bracco D, Basile F, Hemmerling T. Coronary artery bypass grafting in the awake

patient combining high thoracic epidural and femoral nerve block: first series of 15 patients. Br J

Anaesth. 2008;100:184-189.

arkinson SK, Mueller JB, Little WL, Bailey SL. Extent of blockade with various approaches to the

lumbar plexus. Anesth Analg. 1989;68:243-248.

Ritter JW. Femoral nerve “sheath” for inguinal paravascular lumbar plexus block is not found in human

cadavers. J Clin Anesth. 1995;7:470-473.

Rosaeg OP, Krepski B, Cicutti N, Dennehy KC, Lui AC, Johnson DH. Effect of preemptive multimodal

analgesia for arthroscopic knee ligament repair. Reg Anesth Pain Med. 2001;26:125-130.

chafhalter-Zoppoth I, Moriggl B. Aspects of femoral nerve block. Reg Anesth Pain Med. 2006;31:92-

93; author reply 93.

chiferer A, Gore C, Gorove L, et al. A randomized controlled trial of femoral nerve blockade

administered preclinically for pain relief in femoral trauma. Anesth Analg. 2007;105:1852-1854;

table of contents.

chulz-Stubner S, Henszel A, Hata JS. A new rule for femoral nerve blocks. Reg Anesth Pain Med.

2005;30:473-477.

eeberger MD, Urwyler A. Paravascular lumbar plexus block: block extension after femoral nerve

stimulation and injection of 20 vs. 40 ml mepivacaine 10 mg/ml. Acta Anaesthesiol Scand.

1995;39:769-773.

ingelyn FJ, Vanderelst PE, Gouverneur JM. Extended femoral nerve sheath block after total hip

arthroplasty: continuous versus patient-controlled techniques. Anesth Analg. 2001;92:455-459.

Vloka JD, Hadžić; A, Drobnik L, Ernest A, Reiss W, Thys DM. Anatomical landmarks for femoral

nerve block: a comparison of four needle insertion sites. Anesth Analg. 1999;89:1467-1470.

Vloka JD, Hadžić; A, Mulcare R, Lesser JB, Kitain E, Thys DM. Femoral and genitofemoral nerve

blocks versus spinal anesthesia for outpatients undergoing long saphenous vein stripping surgery.

Anesth Analg. 1997;84:749-752.

Wang H, Boctor B, Verner J. The effect of single-injection femoral nerve block on rehabilitation and

length of hospital stay after total knee replacement. Reg Anesth Pain Med. 2002;27:139-144.

Williams BA, Bottegal MT, Kentor ML, Irrgang JJ, Williams JP. Rebound pain scores as a function of

femoral nerve block duration after anterior cruciate ligament reconstruction: retrospective analysis of

a prospective, randomized clinical trial. Reg Anesth Pain Med. 2007;32:186-192.

Williams BA, Kentor ML, Irrgang JJ, Bottegal MT, Williams JP. Nausea, vomiting, sleep, and

restfulness upon discharge home after outpatient anterior cruciate ligament reconstruction with

regional anesthesia and multimodal analgesia/antiemesis. Reg Anesth Pain Med. 2007;32:193-202.

Winnie AP, Ramamurthy S, Durrani Z. The inguinal paravascular technic of lumbar plexus anesthesia:

the “3-in-1 block.” Anesth Analg. 1973;52:989-996.

Wulf H, Lowe J, Gnutzmann KH, Steinfeldt T. Femoral nerve block with ropivacaine or bupivacaine in

day case anterior crucial ligament reconstruction. Acta Anaesthesiol Scand. 2010;54:414-420.

YaDeau JT, Cahill JB, Zawadsky MW, et al. The effects of femoral nerve blockade in conjunction with

epidural analgesia after total knee arthroplasty. Anesth Analg. 2005;101:891-895.

Yazigi A, Madi-Gebara S, Haddad F, Hayeck G, Tabet G. Intraoperative myocardial ischemia in

peripheral vascular surgery: general anesthesia vs combined sciatic and femoral nerve blocks. J Clin

Anesth. 2005;17:499-503.

Continuous Femoral Nerve Block

Allen JG, Denny NM, Oakman N. Postoperative analgesia following total knee arthroplasty: a study

comparing spinal anesthesia and combined sciatic femoral 3-in-1 block. Reg Anesth Pain Med.

1998;23:142-146.

Barrington MJ, Olive D, Low K, Scott DA, Brittain J, Choong P. Continuous femoral nerve blockade or

epidural analgesia after total knee replacement: a prospective randomized controlled trial. Anesth

Analg. 2005;101:1824-1829.

Barrington MJ, Olive DJ, McCutcheon CA, et al. Stimulating catheters for continuous femoral nerve

blockade after total knee arthroplasty: a randomized, controlled, double-blinded trial. Anesth Analg.

2008;106:1316-1321.

Birnbaum J, Volk T. Use of a stimulating catheter for femoral nerve block. Br J Anaesth. 2006;96:139.

Brodner G, Buerkle H, Van Aken H, et al. Postoperative analgesia after knee surgery: a comparison of

three different concentrations of ropivacaine for continuous femoral nerve blockade. Anesth Analg.

2007;105:256-262.

Capdevila X, Barthelet Y, Biboulet P, Ryckwaert Y, Rubenovitch J, d’Athis F. Effects of perioperative

analgesic technique on the surgical outcome and duration of rehabilitation after major knee surgery.

Anesthesiology. 1999;91:8-15.

Capdevila X, Biboulet P, Morau D, et al. Continuous three-in-one block for postoperative pain after

lower limb orthopedic surgery: where do the catheters go? Anesth Analg. 2002;94:1001-1006.

Capdevila X, Pirat P, Bringuier S, et al. Continuous peripheral nerve blocks in hospital wards after

orthopedic surgery: a multicenter prospective analysis of the quality of postoperative analgesia and

complications in 1,416 patients. Anesthesiology. 2005;103:1035-1045.

Cuvillon P, Ripart J, Lalourcey L, et al. The continuous femoral nerve block catheter for postoperative

analgesia: bacterial colonization, infectious rate and adverse effects. Anesth Analg. 2001;93:1045-

1049.

Dauri M, Fabbi E, Mariani P, et al. Continuous femoral nerve block provides superior analgesia

compared with continuous intra-articular and wound infusion after anterior cruciate ligament

reconstruction. Reg Anesth Pain Med. 2009;34:95-99.

Dauri M, Sidiropoulou T, Fabbi E, et al. Efficacy of continuous femoral nerve block with stimulating

catheters versus nonstimulating catheters for anterior cruciate ligament reconstruction. Reg Anesth

Pain Med. 2007;32:282-287.

Eipe N, McCartney CJ, Kummer C. Transient neurological dysfunction after continuous femoral nerve

block: should this change our practice? Anesthesiology. 2007;107:177-178.

Hadzic A, Houle TT, Capdevila X, Ilfeld BM. Femoral nerve block for analgesia in patients having

knee arthroplasty. Anesthesiology. 2010;113(5):1014-1015.

Hayek SM, Ritchey RM, Sessler D, et al. Continuous femoral nerve analgesia after unilateral total knee

arthroplasty: stimulating versus nonstimulating catheters. Anesth Analg. 2006;103:1565-1570.

Hirst GC, Lang SA, Dust WN, Cassidy JD, Yip RW. Femoral nerve block. Single injection versus

continuous infusion for total knee arthroplasty. Reg Anesth. 1996;21:292-297.

feld BM, Le LT, Meyer RS, et al. Ambulatory continuous femoral nerve blocks decrease time to

discharge readiness after tricompartment total knee arthroplasty: a randomized, triple-masked,

placebo-controlled study. Anesthesiology. 2008;108:703-713.

feld BM, Moeller LK, Mariano ER, Loland VJ, Stevens-Lapsley JE, Fleisher AS, Girard PJ, Donohue

MC, Ferguson EJ, Ball ST. Continuous peripheral nerve blocks: is local anesthetic dose the only

factor, or do concentration and volume influence infusion effects as well? Anesthesiology.

2010;112:347-354.

feld BM, Mariano ER, Williams BA, Woodard JN, Macario A. Hospitalization costs of total knee

arthroplasty with a continuous femoral nerve block provided only in the hospital versus on an

ambulatory basis: a retrospective, case-control, cost-minimization analysis. Reg Anesth Pain Med.

2007;32:46-54.

feld BM, Meyer RS, Le LT, et al. Health-related quality of life after tricompartment knee arthroplasty

with and without an extended-duration continuous femoral nerve block: a prospective, 1-year followup of a randomized, triple-masked, placebo-controlled study. Anesth Analg. 2009;108:1320-1325.

feld BM, Moeller LK, Mariano ER, et al. Continuous peripheral nerve blocks: is local anesthetic dose

the only factor, or do concentration and volume influence infusion effects as well? Anesthesiology.

2010;112:347-354.

Kadic L, Boonstra MC, De Waal Malefijt MC, Lako SJ, Van Egmond J, Driessen JJ. Continuous

femoral nerve block after total knee arthroplasty? Acta Anaesthesiol Scand. 2009;53:914-920.

Morin AM, Eberhart LH, Behnke HK, et al. Does femoral nerve catheter placement with stimulating

catheters improve effective placement? A randomized, controlled, and observer-blinded trial. Anesth

Analg. 2005;100:1503-1510.

Morin AM, Kratz CD, Eberhart LH, et al. Postoperative analgesia and functional recovery after totalknee replacement: comparison of a continuous posterior lumbar plexus (psoas compartment) block, a

continuous femoral nerve block, and the combination of a continuous femoral and sciatic nerve block.

Reg Anesth Pain Med. 2005;30:434-445.

Paul JE, Arya A, Hurlburt L, Cheng J, Thabane L, Tidy A, Murthy Y. Femoral nerve block improves

analgesia outcomes after total knee artheoplasty: meta-analysis of randomized controlled trials.

Anesthesiology. 2010;113:1144-1162.

Pham Dang C, Difalco C, Guilley J, Venet G, Hauet P, Lejus C. Various possible positions of

conventional catheters around the femoral nerve revealed by neurostimulation. Reg Anesth Pain Med.

2009;34:285-289.

Pham Dang C, Gautheron E, Guilley J, et al. The value of adding sciatic block to continuous femoral

block for analgesia after total knee replacement. Reg Anesth Pain Med. 2005;30:128-133.

Pham Dang C, Guilley J, Dernis L, et al. Is there any need for expanding the perineural space before

catheter placement in continuous femoral nerve blocks? Reg Anesth Pain Med. 2006;31:393-400.

Salinas FV, Liu SS, Mulroy MF. The effect of single-injection femoral nerve block versus continuous

femoral nerve block after total knee arthroplasty on hospital length of stay and long-term functional

recovery within an established clinical pathway. Anesth Analg. 2006;102:1234-1239.

Salinas FV, Neal JM, Sueda LA, Kopacz DJ, Liu SS. Prospective comparison of continuous femoral

nerve block with nonstimulating catheter placement versus stimulating catheter-guided perineural

placement in volunteers. Reg Anesth Pain Med. 2004;29:212-220.

Shum CF, Lo NN, Yeo SJ, Yang KY, Chong HC, Yeo SN. Continuous femoral nerve block in total knee

arthroplasty: immediate and two-year outcomes. J Arthroplasty. 2009;24:204-209.

Singelyn FJ, Gouverneur JM. Extended “three-in-one” block after total knee arthroplasty: continuous

versus patient-controlled techniques. Anesth Analg. 2000;91:176-180.

Williams BA, Kentor ML, Vogt MT, et al. Reduction of verbal pain scores after anterior cruciate

ligament reconstruction with 2-day continuous femoral nerve block: a randomized clinical trial.

Anesthesiology. 2006;104:315-327.

Chapter 22 Ankle Block

FIGURE 22-1. Needle insertion for saphenous nerve block of the ankle.

General Considerations

An ankle block is essentially a block of four terminal branches of the sciatic nerve (deep and

superficial peroneal, tibial, and sural) and one cutaneous branch of the femoral nerve (saphenous).

Ankle block is simple to perform, essentially devoid of systemic complications, and highly effective

for a wide variety of procedures on the foot and toes. For this reason, this technique should be in the

arma mentarium of every anesthesiologist. At our institution, an ankle block is most commonly used in

podiatric surgery and foot and toe debridement or amputation.

Functional Anatomy

It is useful to think of the ankle block as a block of two deep nerves (posterior tibial and deep

peroneal) and three superficial nerves (saphenous, sural, and superficial peroneal). This concept is

important for success of the block because the two deep nerves are anesthetized by injecting local

anesthetic under the fascia, whereas the three superficial nerves are anesthetized by a simple

subcutaneous injection of local anesthetic.

Common Peroneal Nerve

The common peroneal nerve separates from the tibial nerve and descends alongside the tendon of the

biceps femoris muscle and around the neck of the fibula. Just below the head of the fibula, the

common peroneal nerve divides into its terminal branches: the deep peroneal and superficial

peroneal nerves. The peroneus longus muscle covers both nerves.

Deep Peroneal Nerve

The deep peroneal nerve runs downward below the layers of the peroneus longus, extensor digitorum

longus, and extensor hallucis longus muscles to the front of the leg (Figure 22-2). At the ankle level,

the nerve lies anterior to the tibia and the interosseous membrane and close to the anterior tibial

artery. It is usually sandwiched between the tendons of the anterior tibial and extensor digitorum

longus muscles. At this point, it divides into two terminal branches for the foot: the medial and the

lateral. The medial branch passes over the dorsum of the foot, along the medial side of the dorsalis

pedis artery, to the first interosseous space, where it supplies the web space between the first and

second toe. The lateral branch of the deep peroneal nerve is directed anterolaterally, penetrates and

innervates the extensor digitorum brevis muscle, and terminates as the second, third, and fourth dorsal

interosseous nerves. These branches provide innervation to the tarsometatarsal, metatarsophalangeal,

and interphalangeal joints of the lesser toes.

FIGURE 22-2. Anatomy of the ankle. artery dorsal pedis, deep peroneal nerve.

Superficial Peroneal Nerve

The superficial peroneal nerve (also called the musculocutaneous nerve of the leg) provides muscular

branches to the peroneus longus and brevis muscles. After piercing the deep fascia covering the

muscles, the nerve eventually emerges from the anterolateral compartment of the lower part of the leg

and surfaces from beneath the fascia 5 to 10 cm above the lateral malleolus (Figure 22-3). At this

point, it divides into terminal cutaneous branches: the medial and the lateral dorsal cutaneous nerves

(Figure 22-4A and B). These branches carry sensory innervation to the dorsum of the foot and

communicate with the saphenous nerve medially, as well as the deep peroneal nerve in the first web

space and the sural nerve on the lateral aspect of the foot.

FIGURE 22-3. Anatomy of the ankle. superficial peroneal nerve, sural nerve.

FIGURE 22-4. (A) Anatomy of the ankle. Sural nerve. , Superficial peroneal nerve. (B)

Anatomy of the ankle. Sural nerve, Superficial peroneal nerve.

Tibial Nerve

The tibial nerve separates from the common popliteal nerve proximal to the popliteal fossa crease

and joins the tibial artery behind the knee joint. The nerve runs distally in the thick neurovascular

fascia and emerges at the inferior third of the leg from beneath the soleus and gastrocnemius muscles

on the medial border of the Achilles tendon (Figure 22-5). At the level of the medial malleolus, the

tibial nerve is covered by the superficial and deep fasciae of the leg. It is positioned laterally and

posteriorly to the posterior tibial artery and midway between the posterior aspect of the medial

malleolus and the posterior aspect of the Achilles tendon. Just beneath the malleolus, the nerve

divides into lateral and medial plantar nerves. The posterior tibial nerve provides cutaneous,

articular, and vascular branches to the ankle joint, medial malleolus, inner aspect of the heel, and

Achilles tendon. It also branches to the skin, subcutaneous tissue, muscles, and bones of the sole.

FIGURE 22-5. Anatomy of the ankle. flexor digitorum longus tendon, posterior tibial artery,

tibial nerve, flexor hallucis longus.

Sural Nerve

The sural nerve is a sensory nerve formed by a union of the medial sural nerve (a branch of the tibial

nerve) and the lateral sural nerve (a branch of the common peroneal nerve). The sural nerve courses

between the heads of the gastrocnemius muscle, and after piercing the fascia covering the muscles, it

emerges on the lateral aspect of the Achilles tendon 10 to 15 cm above the lateral malleolus (Figure

22-4A and B). After providing lateral calcaneal branches to the heel, the sural nerve descends behind

the lateral malleolus, supplying the lateral malleolus, Achilles tendon, and ankle joint. The sural

nerve continues on the lateral aspect of the foot, innervating the skin, subcutaneous tissue, fourth

interosseous space, and fifth toe.

Saphenous Nerve

The saphenous nerve is a terminal cutaneous branch (or branches) of the femoral nerve. Its course is

in the subcutaneous tissue of the skin on the medial aspect of the ankle and foot (Figure 22-6).

FIGURE 22-6. Anatomy of the ankle. , saphenous nerve, medial malleolus.

TIP

All superficial (cutaneous) nerves of the foot should be thought of as a neuronal network rather than as

single strings of nerves with a well-defined, consistent anatomic position).

Distribution of Blockade

An ankle block results in anesthesia of the foot. However, note that an ankle block does not result in

anesthesia of the ankle itself. The proximal extension of the blockade is to the level at which the block

is performed. The more proximal branches of the tibial and peroneal nerves innervate the deep

structures of the ankle joint (see Chapter 01, Essential Regional Anesthesia Anatomy). The two deep

nerves (tibial and deep peroneal) provide innervation to the deep structures, bones, and cutaneous

coverage of the sole and web between the first and second toes (Figure 22-7).

FIGURE 22-7. Innervation of the foot.

Equipment

A standard regional anesthesia tray is prepared with the following equipment:

Sterile towels and gauze packs

Three 10-mL syringes containing local anesthetic

Sterile gloves; marking pen

1.5-in, 25-gauge needle

Landmarks and Patient Positioning

The patient is in the supine position with the foot on a footrest.

TIP

Position the foot on a footrest to facilitate access to all nerves to be blocked.

The deep peroneal nerve is located immediately lateral to the tendon of the extensor hallucis

longus muscle (between the extensor hallucis longus and the extensor digitorum longus) (Figure 22-8).

The pulse of the anterior tibial artery (dorsalis pedis) can be felt at this location; the nerve is

positioned immediately lateral to the artery.

FIGURE 22-8. (A) Maneuvers to extenuate the extensor tendons. The deep peroneal nerve is located

lateral to the hallucis longus tendon (line). (B) Deep peroneal block. The needle is inserted just

lateral to the hallucis longus tendon and slowly advanced to contact the bone. Upon bone contact, the

needle is withdrawn 2–3 mm, and 5 mL of local anesthetic is injected.

The posterior tibial nerve is located just behind and distal to the medial malleolus. The pulse of

the posterior tibial artery can be felt at this location; the nerve is just posterior to the artery.

The superficial peroneal, sural, and saphenous nerves are located in the subcutaneous tissue along

a circular line stretching from the lateral aspect of the Achilles tendon across the lateral malleolus,

anterior aspect of the foot, and medial malleolus to the medial aspect of the Achilles tendon.

TIP

The superficial nerves branch out and anastomose extensively; they do not have a single consistently

positioned nerve trunk that can be anesthetized by a single precise injection as often taught.

Techniques

For time-efficient blockade of all five nerves, the operator should walk from one side of the foot to

the other during the block procedure instead of bending and leaning over to reach the opposite side.

Before beginning the procedure, the entire foot should be cleaned with a disinfectant. It makes sense

to begin this procedure with blocks of the two deep nerves because subcutaneous injections for the

superficial blocks often deform the anatomy. A controlled or regular syringe can be used.

Deep Peroneal Nerve Block

The finger of the palpating hand is positioned in the groove just lateral to the extensor hallucis longus

(Figure 22-8A). The needle is inserted under the skin and advanced until stopped by the bone. At this

point, the needle is withdrawn back 1 to 2 mm, and 2 to 3 mL of local anesthetic is injected (Figure

22-8B).

TIP

A deep peroneal block is essentially a “blind” injection of local anesthetic. Instead of relying on a

single injection, a “fan” technique is recommended to increase the success rate after the injection.

The tendon of extensor hallucis longus can be accentuated by asking the patient to dorsiflex the toes.

Posterior Tibial Nerve Block

The posterior tibial nerve is anesthetized by injecting local anesthetic just behind the medial

malleolus (Figure 22-9A). Similar to that of the deep peroneal nerve, its position is deep to the

superficial fascia. The needle is introduced in the groove behind the medial malleolus and advanced

until contact with the bone is felt. At this point, the needle is withdrawn back 1 to 2 mm, and 2 to 3

mL of local anesthetic is injected (Figure 22-9B).

FIGURE 22-9. (A) Landmark for posterior tibial nerve block is found by palpating the pulse of the

tibial artery posterior to the medial malleolus. (B) Posterior tibial nerve block is accomplished by

inserting the needle next to the pulse of the tibial artery. The needle is advanced until contact with the

bone is established. At this point the needle is withdrawn 2–3 mm, and 5 mL of local anesthetic is

injected.

TIP

Similar to the procedure used for the deep peroneal nerve, a “fan” technique should be used to

increase the success rate. The needle is pulled back to the skin, and two additional boluses of 2 mL of

local anesthetic are injected after anterior and posterior needle reinsertions.

Blocks of the Superficial Peroneal, Sural, and Saphenous Nerves

These three nerves are superficial cutaneous extensions of the sciatic and femoral nerves. Because

they are positioned superficially to the deep fascia, an injection of local anesthetic in the territory

through which they descend to the distal foot is adequate to achieve their blockade. Each nerve is

blocked using a simple circumferential injection of local anesthetic subcutaneously (Figures 22-10,

22-11, and 22-12).

To block the saphenous nerve, a 1.5 in, 25-gauge needle is inserted at the level of the medial

malleolus and a “ring” of local anesthetic is raised from the point of needle entry to the Achilles

tendon and anteriorly to the tibial ridge (Figure 22.10). This can be usually accomplished with one or

two needle insertions; 5 mL of local anesthetic suffices.

FIGURE 22-10. Saphenous nerve block is accomplished by injection of local anesthetic in a circular

fashion (line) subcutaneously just above the medial malleolus.

To block the superficial peroneal nerve, the needle is inserted at the tibial ridge and extended

laterally toward the lateral malleolus (Figure 22-11). It is important to raise a subcutaneous “wheal”

during injection, which indicates injection in the proper superficial plane. Five milliliters of local

anesthetic is adequate.

FIGURE 22-11. Superficial peroneal nerve block is performed by injecting local anesthetic in a

circular fashion at the level of the lateral malleolus and extending from anterior to posterior.

To block the sural nerve, the needle is inserted at the level of the lateral malleolus and the local

anesthetic is infiltrated toward the Achilles tendon (Figure 22-12). Five milliliters of local anesthetic

is deposited in a circular fashion to raise a skin “wheal.”

FIGURE 22-12. Sural nerve block is accomplished by injecting local anesthetic in a fanwise fashion

subcutaneously and below the fascia behind the lateral malleolus.

TIP

Remember the subcutaneous position of the superficial nerves and think of their blockade as a “field

block.” A distinct subcutaneous “wheal” should be seen with injection into a proper plane to block

the superficial nerves.

Block Dynamics and Perioperative Management

Ankle block is one of the more uncomfortable block procedures for patients. The reason is that it

involves five separate needle insertions, and subcutaneous injections to block the cutaneous nerves

result in discomfort due to the pressure distension of the skin and nerve endings. Additionally, the foot

is supplied by an abundance of nerve endings and is exquisitely sensitive to needle injections. For

these reasons, this block requires significant premedication to make it acceptable to patients. We

routinely use a combination of midazolam (2–4 mg intravenously) and a narcotic (500–750 μg

alfentanil) to ensure the patient’s comfort during the procedure.

A typical onset time for this block is 10 to 25 minutes, depending primarily on the concentration

and volume of local anesthetic used. Placement of an Esmarch bandage or a tourniquet at the level of

the ankle is well-tolerated and typically does not require additional blockade in sedated patients.

Complications and How to Avoid Them

Complications following an ankle block are typically limited to residual paresthesias due to

inadvertent intraneuronal injection. Systemic toxicity is uncommon because of the distal location of

the blockade. Table 22-1 provides more specific instructions on possible complications and

corrective measures.

TABLE 22-1 Complications of Ankle Block and Preventive Techniques

SUGGESTED READING

Delgado-Martinez AD, Marchal JM, Molina M, Palma A. Forefoot surgery with ankle tourniquet:

complete or selective ankle block? Reg Anesth Pain Med. 2001;26:184-186.

Delgado-Martinez AD, Marchal-Escalona JM. Supramalleolar ankle block anesthesia and ankle

tourniquet for foot surgery. Foot Ankle Int. 2001;22:836-838.

Hadžić; A, Vloka JD, Kuroda MM, Koorn R, Birnbach DJ. The practice of peripheral nerve blocks in

the United States: a national survey. Reg Anesth Pain Med. 1998;23:241-246.

Klein SM, Pietrobon R, Nielsen KC, Warner DS, Greengrass RA, Steele SM. Peripheral nerve

blockade with long-acting local anesthetics: a survey of the Society for Ambulatory Anesthesia.

Anesth Analg. 2002;94:71-76.

Mineo R, Sharrock NE. Venous levels of lidocaine and bupivacaine after midtarsal ankle block. Reg

Anesth. 1992;17:47-49.

Myerson MS, Ruland CM, Allon SM. Regional anesthesia for foot and ankle surgery. Foot Ankle.

1992;13:282-288.

Needoff M, Radford P, Costigan P. Local anesthesia for postoperative pain relief after foot surgery: a

prospective clinical trial. Foot Ankle Int. 1995;16:11-13.

Noorpuri BS, Shahane SA, Getty CJ. Acute compartment syndrome following revisional arthroplasty of

the forefoot: the dangers of ankle-block. Foot Ankle Int. 2000;21:680-682.

Palmisani S, Arcioni R, Di Benedetto P, De Blasi RA, Mercieri M, Ronconi P. Ropivacaine and

levobupivacaine for bilateral selective ankle block in patients undergoing hallux valgus repair. Acta

Anaesthesiol Scand. 2008;52:841-844.

Reilley TE, Gerhardt MA. Anesthesia for foot and ankle surgery. Clin Podiatr Med Surg. 2002;19:125-147, vii.

Reinhart DJ, Stagg KS, Walker KG, et al. Postoperative analgesia after peripheral nerve block for

podiatric surgery: clinical efficacy and chemical stability of lidocaine alone versus lidocaine plus

ketorolac. Reg Anesth Pain Med. 2000;25:506-513.

Rudkin GE, Rudkin AK, Dracopoulos GC. Ankle block success rate: a prospective analysis of 1,000

patients. Can J Anaesth. 2005;52:209-210.

Rudkin GE, Rudkin AK, Dracopoulos GC. Bilateral ankle blocks: a prospective audit. ANZ J Surg.

2005;75:39-42.

Schabort D, Boon JM, Becker PJ, Meiring JH. Easily identifiable bony landmarks as an aid in targeted

regional ankle blockade. Clin Anat. 2005;18:518-526.

Schurman DJ. Ankle-block anesthesia for foot surgery. Anesthesiology. 1976;44:348-352.

Shah S, Tsai T, Iwata T, Hadžić; A. Outpatient regional anesthesia for foot and ankle surgery. Int

Anesthesiol Clin. 2005;43:143-151.

Sharrock NE, Waller JF, Fierro LE. Midtarsal block for surgery of the forefoot. Br J Anaesth.

1986;58:37-40.

Tran D, Clemente A, Finlayson RJ. A review of approaches and techniques for lower extremity nerve

blocks. Can J Anaesth. 2007;54:922-934.

Thoracic Paravertebral Block

FIGURE 23-1. Thoracic paravertebral block.

General Considerations

A thoracic paravertebral block is a technique where a bolus of local anesthetic is injected in the

paravertebral space, in the vicinity of the thoracic spinal nerves following their emergence from the

intervertebral foramen. The resulting ipsilateral somatic and sympathetic nerve blockade produces

anesthesia or analgesia that is conceptually similar to a “unilateral” epidural anesthetic block. Higher

or lower levels can be chosen to accomplish a unilateral, bandlike, segmental blockade at the desired

levels without significant hemodynamic changes. For a trained regional anesthesia practitioner, this

technique is simple to perform and time efficient; however, it is more challenging to teach because it

requires stereotactic thinking and needle maneuvering. A certain “mechanical” mind or sense of

geometry is necessary to master it. This block is used most commonly to provide anesthesia and

analgesia in patients having mastectomy and cosmetic breast surgery, and to provide analgesia after

thoracic surgery or in patients with rib fractures. A catheter can also be inserted for continuous

infusion of local anesthetic.

Regional Anesthesia Anatomy

The thoracic paravertebral space is a wedge-shaped area that lies on either side of the vertebral

column (Figure 23-2). Its walls are formed by the parietal pleura anterolaterally; the vertebral body,

intervertebral disk, and intervertebral foramen medially; and the superior costotransverse ligament

posteriorly. After emerging from their respective intervertebral foramina, the thoracic nerve roots

divide into dorsal and ventral rami. The dorsal ramus provides innervation to the skin and muscle of

the paravertebral region; the ventral ramus continues laterally as the intercostal nerve. The ventral

ramus also gives rise to the rami communicantes, which connect the intercostal nerve to the

sympathetic chain. The thoracic paravertebral space is continuous with the intercostal space laterally,

epidural space medially, and contralateral paravertebral space via the prevertebral fascia. In

addition, local anesthetic can also spread longitudinally either cranially or caudally. The mechanism

of action of a paravertebral blockade includes direct action of the local anesthetic on the spinal nerve,

lateral extension along with the intercostal nerves and medial extension into the epidural space

through the intervertebral foramina.

FIGURE 23-2. Anatomy of the thoracic spinal nerve (root) and innervation of the chest wall.

Distribution of Anesthesia

Thoracic paravertebral blockade results in ipsilateral anesthesia. The location of the resulting

dermatomal distribution of anesthesia or analgesia is a function of the level blocked and the volume

of local anesthetic injected (Figure 23-3).

FIGURE 23-3. Thoracic dermatomal levels.

Single-Injection Thoracic Paravertebral Block

Equipment

A standard regional anesthesia tray is prepared with the following equipment:

Sterile towels and gauze packs

A 20-mL syringe containing local anesthetic

Sterile gloves and marking pen

A 10-mL syringe plus 25-gauge needle with local anesthetic for skin infiltration

An 8-10 cm, 18-gauge Tuohy tip epidural needle for continuous paravertebral block or an 8-10 cm

Quincke tip needle for single injection paravertebral block.

Low-volume extension tubing

TIP

The use of needles with markings to indicate the depth of insertion is suggested for a better monitoring

of needle placement.

Patient Positioning

The patient is positioned in the sitting or lateral decubitus (with the side to be blocked uppermost)

position and supported by an attendant (Figure 23-4). The back should assume knee-chest position,

similar to the position required for neuraxial anesthesia. The patient’s feet rest on a stool to allow

greater patient comfort and a greater degree of kyphosis. The positioning increases the distance

between the adjacent transverse processes and facilitates advancement of the needle between them.

FIGURE 23-4. Patient positioning for thoracic paravertebral block. The patient is positioned in a

sitting position with feet resting on a stool and assumes a knee-chest position.

Landmarks and Maneuvers to Accentuate Them

The following anatomic landmarks are used to identify spinal levels and estimate the position of the

relevant transverse processes (Figure 23-5):

FIGURE 23-5. Spinal processes are the main landmarks for the thoracic paravertebral block.

Processes are outlined from C7 (the most prominent vertebrate) to T7 (tip of scapulae).

. Spinous processes (midline)

. Spinous process of C7 (the most prominent spinous process in the cervical region when the neck is

flexed)

. Lower tips of scapulae (corresponds to T7)

The tips of the spinous processes should be marked on the skin. Then a parasagittal line can be

measured and drawn 2.5 cm lateral to the midline (Figure 23-6). For breast surgery, the levels to be

blocked are T2 through T6. For thoracotomy, estimates can be made after discussion with the surgeon

about the planned approach and length of incision.

FIGURE 23-6. The needle insertion points for paravertebral block are labeled 2.5 cm lateral to the

spinous processes.

TIP

Determining the distance between two transverse processes at the level to be blocked is a rough

estimation at best. Instead, it is more practical to outline the midline and simply draw an arbitrary line

2.5 cm parallel and lateral to the midline. Once the two first transverse processes are identified on

that line, the rest follow a similar cranial-caudal distance between the two processes.

Technique

After cleaning the skin with an antiseptic solution, 6 to 10 mL of dilute local anesthetic is infiltrated

subcutaneously along the line where the injections will be made. The injection should be carried out

slowly to avoid pain on injection.

TIPS

The addition of a vasoconstrictor helps prevent oozing at the site of injection.

When more than five or six levels are blocked (e.g., bilateral blocks), the use of alkalinized

chloroprocaine or lidocaine for skin infiltration is suggested to decrease the total dose of long-acting

local anesthetic.

The subcutaneous tissues and paravertebral muscles are infiltrated with local anesthetic to

decrease the discomfort at the site of needle insertion. The fingers of the palpating hand should

straddle the paramedian line and fix the skin to avoid medial-lateral skin movement. The needle is

attached to a syringe containing local anesthetic via extension tubing and advanced perpendicularly to

the skin at the level of the superior aspect of the corresponding spinous process (Figure 23-7).

Constant attention to the depth of needle insertion and the slight medial to lateral needle orientation is

critical to avoid pneumothorax and direction of the needle toward the neuraxial space, respectively.

The utmost care should be taken to avoid directing the needle medially (risk of epidural or spinal

injection). The transverse process is typically contacted at a depth of 3 to 6 cm. If it is not, it is

possible the needle tip has missed the transverse processes and passed either too laterally or in

between the processes. Osseous contact at shallow depth (e.g., 2 cm) is almost always due to a too

lateral needle insertion (ribs). In this case, further advancement could result in too deep insertion and

possible pleural puncture. Instead, the needle should be withdrawn and redirected superiorly or

inferiorly until contact with the bone is made.

FIGURE 23-7. The technique of thoracic paravertebral block begins with insertion of the needle 2.5

cm lateral to the spinous process with an intention to contact the transverse process.

After the transverse process is contacted, the needle is withdrawn to the skin level and redirected

superiorly or inferiorly to “walk off” the transverse process (Figure 23-8A and B). The ultimate goal

is to insert the needle to a depth of 1 cm past the transverse process. A certain loss of resistance to

needle advancement often can be felt as the needle passes through the superior costotransverse

ligament; however, this is a nonspecific sign and should not be relied on for correct placement.

FIGURE 23-8. (A) Once the transverse process is contacted, the needle is walked-off superiorly or

inferiorly and advanced 1–1.5 cm past the transverse process. (B) When walking-off the transverse

process superiorly proves difficult, the needle is redirected to walk off inferiorly.

TIP

• The block procedure consists of three maneuvers (Figure 23-9):

Contact the transverse processes of individual vertebra and note the depth at which the process

was contacted (usually 2–4 cm) (Figure 23-9A).

Withdraw the needle to the skin level and reinsert it at a 10° caudal or cephalad angulation

(Figure 23-9B).

Walk off the transverse process, pass the needle 1 cm deeper and inject 5 mL of local anesthetic

(Figure 23-9C).

FIGURE 23-9. Demonstration of the technique of walking-off the transverse process and needle

redirection maneuvers to enter the paravertebral space (lightly shaded area) containing thoracic nerve

roots. A. Needle contacts transverse process. B. Needle is “walked off” cephalad to reach

paravertebral space. C. Needle is “walked off” to reach paravertebral space.

The needle can be redirected to walk off the transverse process superiorly or inferiorly. At levels

of T7 and below, however, walking off the inferior aspect of the transverse process is recommended

to reduce the risk of intrapleural placement of the needle. Proper handling of the needle is important

both for accuracy and safety. Once the transverse process is contacted, the needle should be regripped 1 cm away from the skin so that insertion only can be made 1 cm deeper before skin contact

with the fingers prevents further advancement.

After aspiration to rule out intravascular or intrathoracic needle tip placement, 5 mL of local

anesthetic is injected slowly (Figure 23-10). The process is repeated for the remaining levels to be

blocked.

FIGURE 23-10. The spread of the contrast-containing local anesthetic in the paravertebral space.

White arrow—paravertebral catheter, blue arrows—spread of the contrast. In right image example (5

ml), the contrast spreads somewhat contralaterally and one level above and below the injection.

TIPS

Loss of resistance technique to identify the paravertebral is subtle. For this reason, we do not rely on

the loss of resistance as a marker. Instead, we measure the skin–transverse process distance and

simply advance the needle 1 cm past the transverse process.

Never redirect the needle medially because of the risk of intraforaminal needle passage and

consequent spinal cord injury or subarachnoid injection (total spinal).

Use common sense when advancing the needle. The depth at which the transverse processes are

contacted varies with a patient’s body habitus and the level at which the block is performed. The

deepest levels are at the high thoracic (T1 and T2) and low lumbar levels (L4 and L5), where the

transverse process is contacted at a depth of 6 to 8 cm in average-size patients. The shallowest depths

are at the midthoracic levels (T5 and T10), where the transverse process is contacted at 3 to 4 cm in

an average-size patient.

Never disconnect the needle from the tubing or the syringe containing local anesthetic while the needle

is inserted. Instead, use a stopcock to switch from syringe to syringe during injection. This may

prevent the development of a pneumothorax during inspiration in the case of inadvertent puncture of

the parietal.

Choice of Local Anesthetic

It is usually beneficial to achieve longer-acting anesthesia or analgesia in a thoracic paravertebral

blockade by using a long-acting local anesthetic. Unless lower lumbar levels (L2 through L5) are part

of the planned blockade, paravertebral blocks do not result in extremity motor block and do not

impair the patient’s ability to ambulate or perform activities of daily living.

Table 23-1 lists some commonly used local anesthetic solutions and their dynamics with this

block.

TABLE 23-1 Choice of Local Anesthetic for Paravertebral Block

Block Dynamics and Perioperative Management

Placement of a paravertebral block is associated with moderate patient discomfort, therefore

adequate sedation (midazolam 2–4 mg) is necessary for patient comfort. We also routinely administer

alfentanil 250 to 750 μg just before beginning the block procedure. However, excessive sedation

should be avoided because positioning becomes difficult when patients cannot keep their balance in a

sitting position. The efficacy of the block depends on the dispersion of the anesthetic within the space

to reach the individual roots at the level of the injection. The first sign of the block is the loss of

pinprick sensation at the dermatomal distribution of the root being blocked. The higher the

concentration and volume of local anesthetic used, the faster the onset.

Continuous Thoracic Paravertebral Block

Continuous thoracic paravertebral block is an advanced regional anesthesia technique. Except for the

fact that a catheter is advanced through the needle, however, it differs little from the single-injection

technique. The continuous thoracic paravertebral block technique is more suitable for analgesia than

for surgical anesthesia. The resultant blockade can be thought of as a unilateral continuous thoracic

epidural, although bilateral epidural block after injection through the catheter is not uncommon. This

technique provides excellent analgesia and is devoid of significant hemodynamic effects in patients

following mastectomy, unilateral chest surgery or patients with rib fractures.

Equipment

A standard regional anesthesia tray is prepared with the following equipment:

Sterile towels and gauze packs

A 20-mL syringe containing local anesthetic

Sterile gloves and marking pen

A 3- to 5-mL syringe plus 25-gauge needle with local anesthetic for skin infiltration

Epidural kit with a 10-cm, 18-gauge Tuohy-tip needle and catheter

Patient Positioning

The patient is positioned in the supine or lateral decubitus position. In our experience, this block is

used primarily for patients after various thoracic procedures or for patients undergoing a mastectomy

or tumorectomy with axillary lymph node debridement. The ability to recognize spinous processes is

crucial.

Landmarks

The landmarks for a continuous paravertebral block are identical to those for the single-injection

technique. The tips of the spinous processes should be marked on the skin. A parasagittal line can then

be measured and drawn 2.5 cm lateral to the midline.

TIP

For continuous paravertebral blockade, the catheter is inserted one segmental level below the

midpoint of the thoracotomy incision line.

Technique

The subcutaneous tissues and paravertebral muscles are infiltrated with local anesthetic to decrease

the discomfort at the site of needle insertion. The needle is attached to a syringe containing local

anesthetic via extension tubing and advanced in a sagittal, slightly cephalad plane to contact the

transverse process. Once the transverse process is contacted, the needle is withdrawn back to the skin

level and reinserted cephalad at a 10° to 15° angle to walk off 1 cm past the transverse process and

enter the paravertebral space. As the paravertebral space is entered, a loss of resistance is sometimes

perceived, but it should not be relied on as a marker of correct placement. Once the paravertebral

space is entered, the initial bolus of local anesthetic is injected through the needle. The catheter is

inserted about 3 to 5 cm beyond the needle tip (Figure 23-11). The catheter is secured using an

adhesive skin preparation, followed by application of a clear dressing and clearly labeled

“paravertebral nerve block catheter.” The catheter should be loss of resistance checked for air,

cerebrospinal fluid, and blood before administering a local anesthetic or starting a continuous

infusion.

FIGURE 23-11. Continuous thoracic paravertebral block. The catheter is inserted 3 cm past the

needle tip.

TIPS

Care must be taken to prevent medial orientation of the needle (risk of epidural or subarachnoid

placement).

If it is deemed that the needle is inserted too laterally (inability to advance due to needle-rib contact),

the needle should be reinserted medially rather than oriented medially (to avoid the risk of the needle

entering neuraxial space and spinal cord injury).

Management of the Continuous Infusion

Continuous infusion is initiated after an initial bolus of dilute local anesthetic is administered through

the needle or catheter. The bolus injection consists of a small volume of 0.2% ropivacaine or

bupivacaine (e.g., 8 mL). For continuous infusion, 0.2% ropivacaine or 0.25% bupivacaine

(levobupivacaine) is also suitable. Local anesthetic is infused at 10 mL/h or 5 mL/h when a patientcontrolled regional analgesia dose (5 mL every 60 min) is planned.

TIPS

Breakthrough pain in patients undergoing continuous infusion is always managed by administering a

bolus of local anesthetic; increasing the rate of infusion alone is never adequate.

When the bolus injection through the catheter fails to result in blockade after 30 minutes, the catheter

should be considered dislodged and should be removed.

Complications and How to Avoid Them

Table 23-2 lists the complications and preventive techniques of thoracic paravertebral block.

TABLE 23-2 Complications of Thoracic Paravertebral Block and Preventive Techniques

SUGGESTED READING

Boezaart AP, Raw RM. Continuous thoracic paravertebral block for major breast surgery. Reg Anesth

Pain Med. 2006;31:470-476.

Buckenmaier CC III, Steele SM, Nielsen KC, Martin AH, Klein SM. Bilateral continuous paravertebral

catheters for reduction mammoplasty. Acta Anaesthesiol Scand. 2002;46:1042-1045.

Canto M, Sanchez MJ, Casas MA, Bataller ML. Bilateral paravertebral blockade for conventional

cardiac surgery. Anaesthesia. 2003;58:365-370.

Catala E, Casas JI, Unzueta MC, Diaz X, Aliaga L, Landeira JM. Continuous infusion is superior to

bolus doses with thoracic paravertebral blocks after thoracotomies. J Cardiothorac Vasc Anesth.

1996;10:586-588.

Cheung SL, Booker PD, Franks R, Pozzi M. Serum concentrations of bupivacaine during prolonged

continuous paravertebral infusion in young infants. Br J Anaesth. 1997;79:9-13.

Conacher ID, Kokri M. Postoperative paravertebral blocks for thoracic surgery: a radiological

appraisal. Br J Anaesth. 1987;59:155.

Coveney E, Weltz CR, Greengrass R, et al. Use of paravertebral block anesthesia in the surgical

management of breast cancer: experience in 156 cases. Ann Surg. 1998;227:496-501.

Daly DJ, Myles PS. Update on the role of paravertebral blocks for thoracic surgery: are they worth it?

Curr Opin Anaesthesiol. 2009;22:38-43.

Eng J, Sabanathan S. Continuous paravertebral block for postthoracotomy analgesia in children. J

Pediatr Surg. 1992;27:556-557.

Ganapathy S, Murkin JM, Boyd DW, Dobkowski W, Morgan J. Continuous percutaneous paravertebral

block for minimally invasive cardiac surgery. J Cardiothorac Vasc Anesth. 1999;13:594-596.

Greengrass RA, Klein SM, D’Ercole FJ, Gleason DG, Shimer CL, Steele SM. Lumbar plexus and

sciatic nerve block for knee arthroplasty: comparison of ropivacaine and bupivacaine. Can J

Anaesth. 1998;45:1094-1096.

Hadžić A, Vloka JD, Kuroda MM, Koorn R, Birnbach DJ. The practice of peripheral nerve blocks in

the United States: a national survey. Reg Anesth Pain Med. 1998;23:241-246.

Hultman JL, Schuleman S, Sharp T, Gilbert TJ. Continuous thoracic paravertebral block. J

Cardiothorac Anesth. 1989;3:54.

ohnson LR, Rocco AG, Ferrante FM. Continuous subpleural-paravertebral block in acute thoracic

herpes zoster. Anesth Analg. 1988;67:1105-1108.

Karmakar MK. Thoracic paravertebral block. Anesthesiology. 2001;95:771-780.

Karmakar MK, Booker PD, Franks R. Bilateral continuous paravertebral block used for postoperative

analgesia in an infant having bilateral thoracotomy. Paediatr Anaesth. 1997;7:469-471.

Klein SM, Bergh A, Steele SM, Georgiade GS, Greengrass RA. Thoracic paravertebral block for

breast surgery. Anesth Analg. 2000;90:1402-1405.

Kopacz DJ, Thompson GE. Neural blockade of the thorax and abdomen. In: Cousins MJ, Bridenbaugh

PO, eds. Neuronal Blockade in Clinical Anesthesia and Management of Pain. Philadelphia, PA:

Lippincott-Raven; 1988:451-485.

Norum HM, Breivik H. Thoracic paravertebral blockade and thoracic epidural analgesia: two extremes

of a continuum. Anesth Analg. 2011;112:990; 990-1.

Pintaric TS, Potocnik I, Hadzic A, Stupnik T, Pintaric M, Jankovic VN. Comparison of continuous

thoracic epidural with paravertebral block on perioperative analgesia and hemodynamic stability in

patients having open lung surgery.Reg Anesth Pain Med. 2011;36:256-60.

Pusch F, Wildling E, Klimscha W, Weinstable C. Sonographic measurement of needle insertion depth inparavertebral blocks in women. Br J Anaesth. 2002;85:841-843.

Renes SH, Van Geffen GJ, Snoeren MM, Gielen MJ, Groen GJ. “Ipsilateral brachial plexus block and

hemidiaphragmatic paresis as adverse effect of a high thoracic paravertebral block. Reg Anesth Pain

Med. 2011;36:198-201.

Richardson J, Lönnqvist PA, Naja Z. Bilateral thoracic paravertebral block: potential and practice. Br JAnaesth. 2011;106:164-71.

Richardson J, Sabanathan S, Jones J, Shah RD, Cheema S, Mearns AJ. A prospective, randomized

comparison of preoperative and continuous balanced epidural or paravertebral bupivacaine on postthoracotomy pain, pulmonary function and stress responses. Br J Anaesth. 1999;83:387-392.

Richardson J, Sabanathan S. Thoracic paravertebral analgesia. Acta Anaesthesiol Scand.

1995;39:1005-1015.

Schnabel A, Reichl SU, Kranke P, Pogatzki-Zahn EM, Zahn PK.Efficacy and safety of paravertebral

blocks in breast surgery: a meta-analysis of randomized controlled trials. Br J Anaesth.

2010;105:842-52.

Terheggen MA, Wille F, Borel Rinkes IH, Ionescu TI, Knape JT. Paravertebral blockade for minor

breast surgery. Anesth Analg. 2002;94:355-359.

Terheggen MA, Wille F, Borel Rinkes IH, Ionescu TI, Knape JT. Paravertebral blockade for minor

breast surgery. Anesth Analg. 2002;94:355-359.

Vila H Jr, Liu J, Kavasmaneck D. Paravertebral block: new benefits from an old procedure. Curr Opin

Anaesthesiol. 2007;20:316-318.

Wheeler LJ. Peripheral nerve stimulation end-point for thoracic paravertebral block. Br J Anaesth.

2001;86:598.

Intercostal Block

FIGURE 24-1. Intercostal nerve block: Patient position and needle insertion.

General Considerations

Intercostal block produces discrete bandlike segmental anesthesia in the chosen levels. Intercostal

block is an excellent analgesic option for a variety of acute and chronic pain conditions. The

beneficial effect of intercostal blockade on respiratory function following thoracic or upper

abdominal surgery, or following chest wall trauma, is well documented. Although similar in many

ways to the paravertebral block, intercostal blocks are generally simpler to perform because the

osseous landmarks are more readily palpable. However, the risks of pneumothorax and local

anesthetic systemic toxicity are present, and care must be taken to prevent these potentially serious

complications. Intercostal blocks can be more challenging to perform above the level of T7 because

the scapula prevents access to the ribs. Although an intercostal block is an excellent choice for

analgesic purposes, it is often inadequate as a complete surgical anesthesia. For this application,

supplementation with another anesthesia technique usually is required.

Regional Anesthesia Anatomy

After emerging from their respective intervertebral foramina, the thoracic nerve roots divide into

dorsal and ventral rami (Figure 24-2). The dorsal ramus provides innervation to the skin and muscle

of the paravertebral region; the ventral ramus continues laterally as the intercostal nerve. This nerve

then pierces the posterior intercostal membrane approximately 3 cm lateral to the intervertebral

foramen and enters the subcostal groove of the rib, where it travels inferiorly to the intercostal artery

and vein. Initially, the nerve lies between the parietal pleura and the inner most intercostal muscle.

Immediately proximal to the angle of the rib, it passes into the space between the innermost and

internal intercostal muscles, where it remains for much of the remainder of its course. At the

midaxillary line, the intercostal nerve gives rise to the lateral cutaneous branch, which pierces the

internal and external intercostal muscles and supplies the muscles and skin of the lateral trunk. The

continuation of the intercostal nerve terminates as the anterior cutaneous branch, which supplies the

skin and muscles of the anterior trunk, including the skin overlying the sternum and rectus abdominis.

FIGURE 24-2. Anatomy of the thoracic spinal and intercostal nerves.

Distribution of Anesthesia

Intercostal blockade results in the spread of local anesthetic along the intercostals sulcus underneath

the parietal pleura, leading to ipsilateral anesthesia of the blocked intercostals levels (Figure 24-3).

A larger volume of local anesthetic or more medial injection may result in backtracking of local

anesthetic into the paravertebral space. The extent of the resulting dermatomal distribution of

anesthesia or analgesia is simply a function of the level of blockade. In contrast to paravertebral

blockade, longitudinal (cephalad-caudad) spread between adjacent levels is much less common,

although possible with large volumes of injectate and/or injection sites close to the midline of the

back. In such instances, the local anesthetic can spread between the levels via the overflow into the

paravertebral space.

FIGURE 24-3. Injection of the local anesthetic (red dye) in intercostal space results in a mediallateral spread of the local anesthetic in the intercostal space where the intercostal nerves (arrow) are

contained.

Equipment

A standard regional anesthesia tray is prepared with the following equipment:

Sterile towels and gauze packs

20-mL syringes containing local anesthetic

Sterile gloves and marking pen

A 10-mL syringe plus 25-gauge needle with local anesthetic for skin infiltration

A 1.5-in, 22-gauge needle attached to extension tubing

Patient Positioning

An intercostal block can be performed with the patient in the sitting, lateral decubitus, or prone

positions. With the patient in sitting or lateral position, it is helpful to have the patient’s spine arched

with the arms extended forward. Patients who are prone are best positioned for the block by placing a

pillow under the abdomen and with the arms hanging down from the sides of the bed (Figure 24-4).

This rotates the scapulae laterally and permits access to the angles of the rib above the level of T7

(Figure 24-5).

FIGURE 24-4. The patient position for intercostal block. A pillow is used as an abdominal/pelvic

support. The arms are hanging off the table.

FIGURE 24-5. Technique of palpating the intercostal space. The fingers of the palpating hand are

firmly pressed in the intercostal space 5–7 cm lateral to the midline.

Landmarks and Maneuvers to Accentuate Them

The following anatomic landmarks are used to estimate the position of the relevant ribs.

. Twelfth rib (last rib palpable inferiorly) (Figure 24-6)

FIGURE 24-6. Landmarks for intercostal space are identified first by determining the midline and the

spinous processes (skin marks). Intercostal space is then determined by palpation at each level to be

blocked, and the insertion point for needle is marked 5–7 cm lateral to the midline.

. The 7th rib (lowest rib covered by the angle of the scapula) (Figure 24-7)

FIGURE 24-7. Estimating T7 level at the tip of the scapula.

Once identified by palpation, the inferior border of the corresponding ribs can be marked on the

skin (Figure 24-8). An “x” at the angle of the rib identifies the site of needle insertion, usually about

6–8 cm from the midline. For thoracotomy or upper abdominal incisions, an estimate of the levels

required for effective analgesia can be made after discussion with the surgeon as to the planned

approach and length of incision. Analgesic blocks for rib fractures are planned based on the area of

the injury. Typically, in addition to the estimated dermatomal levels, one additional level above and

one below the estimated levels are also blocked.

FIGURE 24-8. The needle insertion site for intercostal space is labeled 5–7 cm lateral to the

midline.

TIP

Determining the level of the blockade by counting ribs is merely an estimated, rather than a precise,

technique.

Technique

After cleaning the skin with an antiseptic solution, 1–2 mL of dilute local anesthetic is infiltrated

subcutaneously at each planned injection site.

The fingers of the palpating hand should straddle the insertion site at the inferior border of the rib

and fix the skin to avoid unwanted skin movement. A 1.5-in, 22-gauge needle is attached to a syringe

containing local anesthetic via extension tubing and advanced at an angle of approximately 20°

cephalad to the skin (Figure 24-9). Contact with the rib should be made at within 1 cm in most

patients. While maintaining the same angle of insertion, the needle is walked off the inferior border of

the rib as the skin is allowed to return to its initial position. Then the needle is advanced 3 mm below

the inferior margin of the rib, with the goal of placing the tip in the space containing the neurovascular

bundle (i.e., between the internal and innermost intercostal muscles). The end point for advancement

should be the predetermined distance (3 mm).

FIGURE 24-9. Intercostal nerve block: Patient position and needle insertion.

Following negative aspiration for blood or air, 3–5 mL of local anesthetic of insertion and the

needle withdrawn. The process is repeated for the remaining levels of blockade.

TIPS

A perpendicular or caudad angulation of the needle can cause the block failure; maintenance of the 20°

cephalad angle increases the chances that the needle tip will be placed in close proximity to the

intercostal nerve.

Use common sense when advancing the needle. The depth at which the ribs are contacted varies with a

patient’s body habitus, and an absence of bony contact at 1 cm should prompt a reevaluation of

landmarks rather than continued advancement.

Never disconnect the needle from the tubing or the syringe containing local anesthetic while the needle

is inserted. Instead, use a stopcock to switch the syringes. In the case of inadvertent puncture of the

parietal pleura, this strategy prevents the development of a pneumothorax during inspiration, unless

the visceral pleura are punctured also.

In patients with a multiple-level blockade, consider using alkalinized 3-chloroprocaine for skin

infiltration to decrease the total dose of the more toxic, long-acting local anesthetic

Choice of Local Anesthetic

It is usually beneficial to achieve longer-acting anesthesia or analgesia for intercostal blockade by

using a long-acting local anesthetic. Systemic absorption of local anesthetic is high following an

intercostal block, and careful consideration of the dose should precede the block performance to

decrease the risk of systemic toxicity.

Table 24-1 lists some commonly used local anesthetic solutions and their dynamics with this

block.

Table 24-1 Choice of Local Anesthetic for Intercostal Block

Block Dynamics and Perioperative Management

The performance of intercostal blocks is associated with relatively minor patient discomfort, although

needle contact with the periosteum can be uncomfortable. A small dose of midazolam (2 mg) and

alfentanil (250–500 μg) just before beginning the block procedure is usually adequate to decrease the

discomfort. Excessive sedation should be avoided because positioning becomes difficult when

patients cannot keep their balance in a sitting position. The first sign of successful blockade is the loss

of pinprick sensation at the dermatomal distribution of the nerve being blocked. The higher the

concentration and volume of local anesthetic used, the faster the onset.

Complications and How to Avoid Them

Table 24-2 lists the complications of intercostal block and preventive techniques.

Table 24-2 Complications of Intercostal Block and Preventive Techniques

SUGGESTED READING

Finnerty O, Carney J, McDonnell JG. Trunk blocks for abdominal surgery. Anaesthesia. 2010;65(Suppl

1):76-83.

Joshi GP, Bonnet F, Shah R, et al. A systematic review of randomized trials evaluating regional

techniques for postthoracotomy analgesia. Anesth Analg. 2008;107:1026-1040.

Karmakar MK, Critchley LAH, Ho AMH, et al. Continuous thoracic paravertebral infusion of

bupivacaine for pain management in patients with multiple fractured ribs. Chest. 2003;123:424-431.

Karmakar MK, Ho AMH. Acute pain management of patients with multiple fractured ribs. J Trauma.

2003;54:612-615.

Kopacz DJ, Thompson GE. Intercostal blocks for thoracic and abdominal surgery. Tech Reg Anesth

Pain Manage. 1998;2:25-29.

Nunn JF, Slavin G. Posterior intercostal nerve block for pain relief after cholecystectomy. Anatomical

basis and efficacy. Br J Anaesth. 1980;52:253-260.

Osinowo OA, Zahrani M, Softah A. Effect of intercostal nerve block with 0.5% bupivacaine on peak

expiratory flow rate and arterial oxygen saturation in rib fractures. J Trauma. 2004;56:345-347.

Stromskag KE, Kleiven S. Continuous intercostals and interpleural nerve blockades. Tech Reg Anesth

Pain Manage. 1998;2:79-89.

SECTION 3 Intravenous Regional Anesthesia

Chapter 25 Bier Block

FIGURE 25-1. Intravenous regional anesthesia: Injection of local anesthetic and placement of the

tourniquet.

General Considerations

Intravenous regional anesthesia (IVRA) was first described in 1908 by the German surgeon A.G.

Bier, hence the procedure name Bier block. Originally, anesthesia was obtained by the intravenous

injection of procaine in a previously exsanguinated vascular space, isolated from the rest of the

circulation by two Esmarch bandages used as tourniquets. After initial enthusiasm, the technique fell

into obscurity for >50 years. In 1963, Holmes reintroduced the Bier block with the novel use of

lidocaine, describing a series of 30 patients in The Lancet. Today, intravenous regional anesthesia of

the upper limb remains popular because it is reliable, cost effective, safe, and simple to administer. It

is a widely accepted technique well suited for brief minor surgeries such as wrist or hand

ganglionectomy, carpal tunnel release, Dupuytren contractures, reduction of fractures, and others.

Since the duration of anesthesia depends on the length of time the tourniquet is inflated, there is no

need to use long-acting or more toxic agents. Its application for longer surgical procedures is

precluded by the discomfort caused by the tourniquet, typically beginning within 30 to 45 minutes.

Other disadvantages include incomplete muscle relaxation (where important) and lack of

postoperative pain relief. With the implementation of a safety protocol and with meticulous attention

to detail, concerns about local anesthetic (LA) toxicity should merely be a theoretical issue.

Anatomy

The only relevant anatomy is the location and distribution of peripheral veins in the extremity to be

blocked. By preference, a vein as distal as possible is chosen. The antecubital fossa is an alternative

only when more distal peripheral access is lacking.

Distribution of Anesthesia

The entire extremity below the level of the tourniquet is anesthetized. Numerous radiographic,

radioisotope, and neurophysiologic studies looked into the site of action of IVRA. However, the exact

mechanism still remains the subject of debate and controversy. The likely mechanism is that the local

anesthetic, via the vascular bed, reaches both peripheral nerves and nerve trunks (vasae nervorum),

and nerve endings (valveless venules). Diffusion of local anesthetic into the surrounding tissues also

plays a role. Ischemia and compression of the peripheral nerves at the level of the inflated cuff is

probably another contributory component of the mechanism of IVRA. Again, anesthesia achieved by

intravenous regional anesthesia is limited only by the inevitable pain due to tourniquet application;

and, therefore, it is used typically for procedures lasting 30 to 45 minutes.

Equipment

Equipment includes the following items (Figure 25-2):

FIGURE 25-2. Equipment for intravenous (IV) regional anesthesia consists of IV catheter, Esmarch,

and local anesthetic.

Local anesthetic agent: lidocaine HCl (0.25–2%)

Rubber tourniquet

IV catheters (18- or 20-gauge)

500-mL or 1-L bag of IV solution (crystalloid)

Infusion set

Pneumatic tourniquet, ideally with a double cuff

One Esmarch bandage (about 150 cm in length, 10 cm in width)

Syringes

Positioning and Preparation

The patient lies in the supine position with the vein selected for block placement readily accessible.

Baseline vital signs are assessed; blood pressure, oxygen saturation, and ECG monitoring are

applied. Intravenous access in the nonoperated extremity is obtained. Small doses of benzodiazepine

for anxiolysis or small aliquots of opioids in case of discomfort, or both, may be administered.

Adequate premedication will improve tourniquet tolerance and benzodiazepines can prevent the

potential central nervous system signs of mild local anesthetic toxicity should the level of local

anesthetic raise. An intact tourniquet system is essential for success and safety. Therefore, pneumatic

cuffs always must be checked for air leaks before starting any IVRA procedure.

Technique

The technique consists of the following steps:

. An IV cannula is inserted in the extremity opposite to the block side.

. A double pneumatic tourniquet is placed on a padding layer of soft cloth (stockinette) with the

proximal cuff high on the upper arm.

. An IV cannula is inserted and carefully secured into a peripheral vein of the operative limb, as far

distally as feasible. The cannula is flushed with saline before capping (Figure 25-3).

FIGURE 25-3. A small gauge intravenous catheter is inserted in the peripheral vein and secured.

. The entire arm is elevated for 1 to 2 minutes to allow for passive exsanguination (Figure 25-4). After

exanguination, while still keeping the arm high, a rubber Esmarch bandage is wrapped around the

arm, spirally from the hand to the distal cuff of the double tourniquet, to exsanguinate the extremity

completely (Figure 25-5).

FIGURE 25-4. A double well-padded tourniquet is placed on the upper arm. The arm is elevated to

allow for passive exsanguinations.

FIGURE 25-5. With the arm elevated, an Esmarch bandage is systematically applied from the

fingertips to the double tourniquet to help empty the venous bed.

. While the axillary artery is digitally occluded, the proximal cuff is inflated to 50 to 100 mm Hg

above systolic arterial blood pressure (Figure 25-6).

FIGURE 25-6. With the Esmarch in place, the double tourniquet is inflated in the following

sequence: The distal cuff (red) is inflated first, followed by inflation of the proximal cuff (blue). Once

the proximal cuff is inflated and checked for functionality, the distal cuff is deflated. The cuff pressure

is determined by the patient’s systolic blood pressure; the cuff pressure should be about 100 mmHg

above the arterial systolic blood pressure.

. Sequence for initial tourniquet management:

. Exsanguinate by elevation and Tourniquet wrapping

. Inflate distal cuff

. Inflate proximal cuff

. Deflate distal cuff

. Inject local anesthetic.

. After reaching the correct pressure, the Esmarch bandage is removed and 12 to 15 mL of

preservative-free 2% lidocaine HCl (or 30–50 mL of 0.5% lidocaine HCl) is slowly injected via the

indwelling extra catheter (20 mL/min) (Figure 25-7). The volume depends on the size of the arm

being anesthetized and the concentration of the anesthetic solution. Commonly recommended maximal

dose is 3 mg/kg.

FIGURE 25-7. With the extremity exsanguinated and the proximal cuff inflated, local anesthetic is

injected to anesthetize the extremity.

. After the injection, the arm is lowered to the level of the table. The IV cannula from the anesthetized

hand is removed, and in a sterile manner, pressure is quickly applied over the puncture site.

0. The onset of anesthesia is almost immediate after injection. When the tourniquet pain is reported by

the patient, the distal cuff should be inflated and the proximal cuff deflated about 25 to 30 minutes

after the beginning of anesthesia (Figure 25-8).

FIGURE 25-8. Management of the tourniquet pain. When the patient complains of tourniquet pain, the

distal cuff (red) is inflated. Once the distal tourniquet is assured to be inflated and functional, the

proximal tourniquet (blue) is deflated. All connectors must be clearly labeled (color coded in our

practice) to avoid error in the sequence of inflation/deflation.

TIPS

• Sequence for managing tourniquet pain:

Inflate distal cuff.

Assure that distal cuff is inflated.

Deflate proximal cuff.

Choice of a Local Anesthetic

Almost all local anesthetic agents have been reported to have been used for IVRA. At present,

lidocaine remains the most commonly used local anesthetic of choice in North America. When used in

the recommended dose of not more than 3 mg/kg, it appears to be remarkably safe in IV regional

blockade. Most researchers report the use of a large volume of a dilute solution of local anesthetic.

We often use a smaller volume of a concentrated agent to simplify by avoiding the need for dilution

and multiple syringes. By using smaller volumes, we find the procedure tends to be more

straightforward and less time consuming; the medication is simpler to prepare and easier to inject.

In some European institutions, prilocaine remains a preferred agent in IVRA. It may be the least

toxic of the drugs used currently, and it is better tolerated than lidocaine in terms of systemic and

central nervous system side effects. However, because it has been associated with the formation of

methemoglobin, prilocaine is not used in North America.

Much research has been done on suitable adjuncts and additives to reduce anesthetic dose and to

obtain improved tourniquet tolerance, better muscle relaxation, and prolonged postoperative pain

control. Research evidence suggests that some adjuvants may offer some benefits. (e.g., ketorolac,

clonidine, meperidine, and muscle relaxants). However, in our opinion, the marginal benefits may not

justify the routine use of any additive because they do not outweigh the risk of increased complexity,

potential for side effects, and drug error that may occur during addition of adjuvants to local

anesthetics.

Block Dynamics and Perioperative Management

With a Bier block, anesthesia of the extremity typically develops within 5 minutes. Progressive

numbness and complete insensitivity are followed by patchy decolorization of the skin and motor

paralysis. Some patients report a tingly or cold sensation in the limb. However, with adequate

premedication, this sign is often missed. After 30 to 45 minutes, the majority of patients report

discomfort at the site of the inflated tourniquet. When this occurs, the distal cuff of the tourniquet

should be inflated and the proximal cuff deflated. This maneuver provides immediate and significant

relief, and the patient gains an additional 15 to 30 minutes of relative comfort. As soon as the patient

gives notice of tourniquet pain, the surgeon should be consulted for information on the expected time

necessary to complete the operation. The proximal tourniquet however, should never be released

before inflation of the distal cuff. Proper labeling of the proximal and distal cuffs and their respective

valves is of the utmost importance. Deflation of the wrong cuff will result in the rapid loss of

anesthesia and the risk of systemic local anesthetic toxicity.

With respect to deflating the tourniquet at the end of a short surgical procedure (i.e., <45 minutes),

it remains important to proceed cautiously. Several protocols for deflation are published. We adhere

to a two-stage deflation: The tourniquet is deflated for 10 seconds and reinflated for 1 minute before

the final release. This sequence results in a more gradual washout of the local anesthetic agent, and,

as such, it reduces the chances of systemic toxicity.

Possible Complications

Untoward sequelae are few. Most of the reports of complications are related to equipment failure or

other factors not directly attributable to the method itself (e.g., neglecting protocol guidelines). Table

25-1 lists complications and ways to prevent them.

TABLE 25-1 Complications and How to Avoid Them

SUGGESTED READING

Bannister M. Bier’s block. Anaesthesia. 1997;52:713.

Blyth MJ, Kinninmonth AW, Asante DK. Bier’s block: a change of injection site. J Trauma.

1995;39:726.

Brown EM, McGriff JT, Malinowski RW. Intravenous regional anaesthesia (Bier block): review of 20

years’ experience. Can J Anaesth. 1989;36:307.

Casale R, Glynn C, Buonocore M. The role of ischaemia in the analgesia which follows Bier’s block

technique. Pain. 1992;50:169.

Choyce A, Peng P. A systematic review of adjuncts for intravenous regional anesthesia for surgical

procedures. Can J Anesth. 2002;49:32-45.

de May JC. Bier’s block. Anaesthesia. 1997;52:713.

Farrell RG, Swanson SL, Walter JR. Safe and effective IV regional anesthesia for use in the emergency

department. Ann Emerg Med. 1985;14:288.

Hadžić A, Vloka JD, Kuroda MM, Koorn R, Birnbach DJ. The practice of peripheral nerve blocks in

the United States: a national survey. Reg Anesth Pain Med. 1998;23:241-246.

Hilgenhurst G. The Bier block after 80 years: a historical review. Reg Anesth. 1990;15:2.

Holmes CM. Intravenous regional neural blockade. In Cousins MJ, Bridenbaugh PO, eds. Neuronal

Blockade in Clinical Anesthesia and Management of Pain. Philadelphia, PA: Lippincott-Raven;

1988:395-409.

Hunt SJ, Cartwright PD. Bier’s block—under pressure? Anaesthesia. 1997;52:188.

Moore DC. Bupivacaine toxicity and Bier block: the drug, the technique, or the anesthetist.

Anesthesiology. 1984;61:782.

Tramer MR, Glynn CJ. Magnesium Bier’s block for treatment of chronic limb pain: a randomised,

double-blind, cross-over study. Pain. 2002;99:235.

Van Zundert A, Helmstadter A, Goerig M. Centennial of intravenous regional anesthesia. Bier’s block

(1908–2008). Reg Anesth Pain Med. 2008;33:483-489.

Wilson JK, Lyon GD. Bier block tourniquet pressure. Anesth Analg. 1989;68:82

SECTION 4 Foundations Of Ultrasound-Guided Nerve Blocks

Chapter 26 Ultrasound Physics

Chapter 27 Optimizing an Ultrasound Image

Chapter 26 Ultrasound Physics

Daquan Xu

Introduction

Ultrasound application allows for noninvasive visualization of tissue structures. Real-time ultrasound

images are integrated images resulting from reflection of organ surfaces and scattering within

heterogeneous tissues. Ultrasound scanning is an interactive procedure involving the operator, patient,

and ultrasound instruments. Although the physics behind ultrasound generation, propagation,

detection, and transformation into practical information is rather complex, its clinical application is

much simpler. Understanding the essential ultrasound physics presented in this chapter should be

useful for comprehending the principles behind ultrasound-guided peripheral nerve blockade.

History of Ultrasound

In 1880, French physicists Pierre Curie, and his elder brother Jacques Curie, discovered the

piezoelectric effect in certain crystals. Paul Langevin, a student of Pierre Curie, developed

piezoelectric materials, which can generate and receive mechanical vibrations with high frequency

(therefore ultrasound). During WWI, ultrasound was introduced in the navy as a means to detect

enemy submarines. In the medical field, however, ultrasound was initially used for therapeutic rather

than diagnostic purposes. In the late 1920s, Paul Langevin discovered that high power ultrasound

could generate heat in bone and disrupt animal tissues. As a result, ultrasound was used to treat

patients with Ménière disease, Parkinson disease, and rheumatic arthritis throughout the early 1950s.

Diagnostic applications of ultrasound began through the collaboration of physicians and SONAR

engineers. In 1942, Karl Dussik, a neuropsychiatrist and his brother, Friederich Dussik, a physicist,

described ultrasound as a diagnostic tool to visualize neoplastic tissues in the brain and the cerebral

ventricles. However, limitations of ultrasound instrumentation at the time prevented further

development of clinical applications until the early 1970s.

With regard to regional anesthesia, as early as 1978, P. La Grange and his colleagues were the

first anesthesiologists to publish a case-series report of ultrasound application for peripheral nerve

blockade. They simply used a Doppler transducer to locate the subclavian artery and performed

supraclavicular brachial plexus block in 61 patients (Figure 26-1). Reportedly, Doppler guidance led

to a high block success rate (98%) and absence of complications such as pneumothorax, phrenic

nerve palsy, hematoma, convulsion, recurrent laryngeal nerve block, and spinal anesthesia.

FIGURE 26-1. Early application of Doppler ultrasound by LaGrange to perform supraclavicular

brachial block.

In 1989, P. Ting and V. Sivagnanaratnam reported the use of B-mode ultrasonography to

demonstrate the anatomy of the axilla and to observe the spread of local anesthetics during axillary

brachial plexus block. In 1994, Stephan Kapral and colleagues systematically explored brachial

plexus with B-mode ultrasound. Since that time, multiple teams worldwide have worked tirelessly on

defining and improving the application of ultrasound imaging in regional anesthesia. Ultrasoundguided nerve blockade is currently used routinely in the practice of regional anesthesia in many

centers worldwide.

Here is a summary of ultrasound quick facts:

1880: Pierre and Jacques Curie discovered the piezoelectric effect in crystals.

1915: Ultrasound was used by the navy for detecting submarines.

1920s: Paul Langevin discovers that high-power ultrasound can generate heat in osseous tissues and

disrupt animal tissues.

1942: Karl and Dussik described ultrasound use as a diagnostic tool.

1950s: Ultrasound was used to treat patients with Ménière disease, Parkinson disease, and rheumatic

arthritis.

1978: P. La Grange published the first case-series of ultrasound application for placement of needles

for nerve blocks.

1989: P. Ting and V. Sivagnanaratnam used ultrasonography to demonstrate the anatomy of the axilla

and to observe the spread of local anesthetics during axillary block.

1994: Steven Kapral and colleagues explored brachial plexus blockade using B-mode ultrasound.

Definition of Ultrasound

Sound travels as a mechanical longitudinal wave in which back-and-forth particle motion is parallel

to the direction of wave travel. Ultrasound is high-frequency sound and refers to mechanical

vibrations above 20 kHz. Human ears can hear sounds with frequencies between 20 Hz and 20 kHz.

Elephants can generate and detect the sound with frequencies <20 Hz for long-distance

communication; bats and dolphins produce sounds in the range of 20 to 100 kHz for precise

navigation (Figure 26-2A and B). Ultrasound frequencies commonly used for medical diagnosis are

between 2 MHz and 15 MHz. However, sounds with frequencies above 100 kHz do not occur

naturally; only human-developed devices can both generate and detect these frequencies, or

ultrasounds.

FIGURE 26-2. (A) Elephants can generate and detect the sound of frequencies <20 Hz for longdistance communication. (B) Bats and dolphins produce sounds in the range of 20–100 kHz for

navigation and spatial orientation.

Piezoelectric Effect

The piezoelectric effect is a phenomenon exhibited by the generation of an electric charge in response

to a mechanical force (squeeze or stretch) applied on certain materials. Conversely, mechanical

deformation can be produced when an electric field is applied to such material, also known the

piezoelectric effect (Figure 26-3). Both natural and human-made materials, including quartz crystals

and ceramic materials, can demonstrate piezoelectric properties. Recently, lead zirconate titanate has

been used as piezoelectric material for medical imaging. Lead-free piezoelectric materials are also

under development. Individual piezoelectric materials produce a small amount of energy. However,

by stacking piezoelectric elements into layers in a transducer, the transducer can convert electric

energy into mechanical oscillations more efficiently. These mechanical oscillations are then

converted into electric energy.

FIGURE 26-3. The piezoelectric effect. Mechanical deformation and consequent oscillation caused

by an electrical field applied to certain material can produce a sound of high frequency.

Ultrasound Terminology

Period is the time it takes for one cycle to occur; the period unit of measure is the microsecond (μs).

Wavelength is the length of space over which one cycle occurs; it is equal to the travel distance

from the beginning to the end of one cycle.

Acoustic velocity is the speed at which a sound wave travels through a medium. It is equal to the

frequency times the wavelength. Speed is determined by the density (ρ) and stiffness (κ) of the

medium (c = (κ/ρ)

1/2). Density is the concentration of medium. Stiffness is the resistance of a

material to compression. Propagation speed increases if the stiffness is increased or the density is

decreased. The average propagation speed in soft tissues is 1540 m/s (ranges from 1400 m/s to 1640

m/s). However, ultrasound cannot penetrate lung or bone tissues.

Acoustic impedance(z) is the degree of difficulty demonstrated by a sound wave being transmitted

through a medium; it is equal to density ρ multiplied by acoustic velocity c (z = ρc). It increases if the

propagation speed or the density of the medium is increased.

Attenuation coefficient is the parameter used to estimate the decrement of ultrasound amplitude in

a certain medium as a function of ultrasound frequency. The attenuation coefficient increases with

increasing frequency; therefore, a practical consequence of attenuation is that the penetration

decreases as frequency increases (Figure 26-4).

FIGURE 26-4. The ultrasound amplitude decreases in certain media as a function of ultrasound

frequency, a phenomenon known as attenuation coefficient. ScN-Sciatic nerve, PA - Popliteal artery.

Ultrasound waves have a self-focusing effect, which refers to the natural narrowing of the

ultrasound beam at a certain travel distance in the ultrasonic field. It is a transition level between

near field and far field. The beam width at the transition level is equal to half the diameter of the

transducer. At the distance of two times the near-field length, the beam width reaches the transducer

diameter. The self-focusing effect amplifies ultrasound signals by increasing acoustic pressure.

In ultrasound imaging, there are two aspects of spatial resolution: axial and lateral. Axial

resolution is the minimum separation of above-below planes along the beam axis. It is determined by

spatial pulse length, which is equal to the product of wavelength and the number of cycles within a

pulse. It can be presented in the following formula:

Axial resolution = wavelength (λ) × number of cycle per pulse = wavelength number of cycle per

pulse

The number of cycles within a pulse is determined by the damping characteristics of the

transducer. The number of cycles within a pulse is usually set between 2 and 4 by the manufacturer of

the ultrasound machines. As an example, if a 2-MHz ultrasound transducer is theoretically used to do

the scanning, the axial resolution would be between 0.8 and 1.6 mm, making it impossible to visualize

a 21-G needle. For a constant acoustic velocity, higher frequency ultrasound can detect smaller

objects and provide a better resolution image. Figure 26-5 shows the images at different resolutions

when a 0.5-mm-diameter object is visualized with three different frequency settings. Lateral

resolution is another parameter of sharpness to describe the minimum side-by-side distance between

two objects. It is determined by both ultrasound frequency and beam width. Lateral resolution can be

improved by focusing to reduce the beam width.

FIGURE 26-5. Ultrasound frequency affects the resolution of the imaged object. Resolution can be

improved by increasing frequency and reducing the beam width by focusing.

Temporal resolution is also important to observe moving objects, such as blood vessels and the

heart. Similar to a movie or cartoon video, the human eye requires that the image be updated at a rate

of approximately 25 times a second or higher for an ultrasound image to appear continuous. However,

imaging resolution is compromised by increasing the frame rate. Optimizing the ratio of resolution to

frame rate is essential to provide the best possible image.

Interactions of Ultrasound Waves with Tissue

As the ultrasound wave travels through tissue, it is subject to a number of interactions. The most

important features are as follows:

Reflection

Scatter

Absorption

When an ultrasound wave encounters boundaries between different media, part of the ultrasound is

reflected and other part is transmitted. The reflected and transmitted directions are given by the

reflection angle θr

and transmission angle θt

, respectively (Figure 26-6).

FIGURE 26-6. The interaction of ultrasound waves through the media in which they travel is

complex. When ultrasound encounters boundaries between different media, part of the ultrasound is

reflected and part transmitted. The reflected and transmitted directions depend on the respective

angles of reflection and transmission.

Reflection of a sound wave is very similar to optical reflection. Some of its energy is sent back

into the originating medium. In a true reflection, reflection angle θr

must equal incidence angle θi

. The

strength of the reflection from an interface is variable and depends on the difference of impedances

between two affinitive media and the incident angle at boundary. If the media impedances are equal,

there is no reflection (no echo). If there is a significant difference between media impedances, there

will be far greater or nearly complete reflection. For example, an interface between soft tissues and

either lung or bone involves a considerable change in acoustic impedance and creates strong echoes.

This reflection intensity is also highly angle dependent, meaning that the ultrasound transducer must be

placed perpendicularly to the target nerve to visualize it clearly.

A change in sound direction when crossing the boundary between two media is called refraction.

If the propagation speed through the second medium is slower than it is through the first medium, the

refraction angle is smaller than the incident angle. Refraction can cause artifacts such as those that

occur beneath large vessels.

During ultrasound scanning, a coupling medium must be used between the transducer and the skin

to displace air from the transducer–skin interface. A variety of gels and oils are applied for this

purpose. They also act as lubricants, providing a smooth surface scanning.

Most scanned interfaces are somewhat irregular and curved. If boundary dimensions are

significantly less than the wavelength or not smooth, the reflected waves will be diffused. Scattering

is the redirection of sound in any direction by rough surfaces or by heterogeneous media (Figure 26-

7). Normally, scattering intensity is much less than mirrorlike reflection intensities and is relatively

independent of the direction of the incident sound wave. Therefore, the visualization of the target

nerve is not significantly influenced by other nearby scattering.

FIGURE 26-7. Scattering is the redirection of ultrasound in any direction caused by rough surfaces

or by heterogeneous media.

Absorption is defined as the direct conversion of sound energy into heat. In other words,

ultrasound scanning generates heat in the tissue. Higher frequencies are absorbed at a greater rate than

lower frequencies. However, higher scanning frequency gives better axial resolution. If the ultrasound

penetration is not sufficient to visualize the structures of interest, a lower frequency is selected to

increase the penetration. The use of longer wavelengths (lower frequency) results in lower resolution

because the resolution of ultrasound imaging is proportional to the wavelength of the imaging wave.

Frequencies between 6 and 12 MHz typically yield better resolution for imaging of the peripheral

nerves because they are located more superficially. Lower imaging frequencies, between 2 and 5

MHz, are usually needed for imaging of neuraxial structures. For most clinical applications,

frequencies less than 2 MHz or higher than 15 MHz are rarely used because of insufficient resolution

or insufficient penetration, respectfully.

Ultrasound Image Modes

A-Mode

The A-mode is the oldest ultrasound modality, dating back to 1930. The transducer sends a single

pulse of ultrasound into the medium and waits for the returned signal. Consequently, a simple onedimensional ultrasound image is generated as a series of vertical peaks corresponding to the depth of

the structures at which the ultrasound beam encounters different tissues. The distance between the

echoed spikes (Figure 26-8) can be calculated by dividing the speed of the ultrasound in the tissue

(1540 m/sec) by half the elapsed time. This mode provides little information on the spatial

relationships of the imaged structures, however. Therefore, A-mode ultrasound is not used in regional

anesthesia.

FIGURE 26-8. The A-mode of ultrasound consists of a one-dimensional ultrasound image displayed

as a series of vertical peaks corresponding to the depth of structures at which the ultrasound

encounters different tissues.

B-Mode

The B-mode supplies a two-dimensional image of the area by simultaneously scanning from a linear

array of 100–300 piezoelectric elements rather than a single one, as is the case in A-mode. The

amplitude of the echo from a series of A-scans is converted into dots of different brightness in Bmode imaging. The horizontal and vertical directions represent real distances in tissue, whereas the

intensity of the grayscale indicates echo strength (Figure 26-9). B mode can provide a cross sectional

image through the area of interest and is the primary mode currently used in regional anesthesia.

FIGURE 26-9. An example of B-mode imaging. The horizontal and vertical directions represent

distances and tissues, whereas the intensity of the grayscale indicates echo strength. Scmsternocleidomastoid muscle, IJV-Internal jugular vein, CA-carotid artery, Th-Thyroid gland.

Doppler Mode

The Doppler effect is based on the work of Austrian physicist Johann Christian Doppler. The term

describes a change in the frequency or wavelength of a sound wave resulting from relative motion

between the sound source and the sound receiver. In other words, at a stationary position, the sound

frequency is constant. If the sound source moves toward the sound receiver, a higher pitched sound

occurs. If the sound source moves away from the receiver, the received sound has a lower pitch

(Figure 26-10).

FIGURE 26-10. The Doppler effect. When a sound source moves away from the receiver, the

received sound has a lower pitch and vice versa.

Color Doppler produces a color-coded map of Doppler shifts superimposed onto a B-mode

ultrasound image. Blood flow direction depends on whether the motion is toward or away from the

transducer. Selected by convention, red and blue colors provide information about the direction and

velocity of the blood flow. According to the color map (color bar) in the upper left-hand corner of the

figure (Figure 26-11), the red color on the top of the bar denotes the flow coming toward the

ultrasound probe, and the blue color on the bottom of the bar indicates the flow away from the probe.

In ultrasound-guided peripheral nerve blocks, color Doppler mode is used to detect the presence and

nature of the blood vessels (artery vs. vein) in the area of interest. When the direction of the

ultrasound beam changes, the color of the arterial flow switches from blue to red, or vice versa,

depending on the convention used. Power Doppler is up to five times more sensitive in detecting

blood flow than color Doppler and it is less dependent on the scanning angle. Thus power Doppler

can be used to identify the smaller blood vessels more reliably. The drawback is that power Doppler

does not provide any information on the direction and speed of blood flow (Figure 26-12).

FIGURE 26-11. Color Doppler produces a color-coded map of Doppler shapes superimposed onto a

B-mode ultrasound image. Selected by convention, red and blue colors provide information about the

direction and velocity of the blood flow.

FIGURE 26-12. Although the power Doppler may be useful in identifying smaller blood vessels, the

drawback is that it does not provided information on the direction and speed of blood flow.

M-Mode

A single beam in an ultrasound scan can be used to produce a picture with a motion signal, where

movement of a structure such as a heart valve can be depicted in a wave-like manner. M-mode is used

extensively in cardiac and fetal cardiac imaging; however, its present use in regional anesthesia is

negligible (Figure 26-13).

FIGURE 26-13. M-mode consists of a single beam used to produce an image with a motion signal.

Movement of a structure can be depicted in a wavelike matter.

Ultrasound Instruments

Ultrasound machines convert the echoes received by the transducer into visible dots, which form the

anatomic image on ultrasound screen. The brightness of each dot corresponds to the echo strength,

producing what is known as a grayscale image.

Two types of scan transducers are used in regional anesthesia: linear and curved. A linear

transducer can produce parallel scan lines and rectangular display, called a linear scan, whereas a

curved transducer yields a curvilinear scan and arc-shaped image (Figure 26-14A and B). In clinical

scanning, even a very thin layer of air between the transducer and skin may reflect virtually all the

ultrasound, hindering any penetration into the tissue. Therefore, a coupling medium, usually an

aqueous gel, is applied between surfaces of the transducer and skin to eliminate the air layer. The

ultrasound machines currently used in regional anesthesia provide a two-dimensional image, or

“slice.” Machines capable of producing three-dimensional images have recently been developed.

Theoretically, three-dimensional (3D) imaging should help in understanding the relationship of

anatomic structures and spread of local anesthetics. (Figure 26-14C and D). At present, however,

3D-real time imaging systems still lack the resolution and simplicity of 2D images, so their practical

use in regional anesthesia is limited.

FIGURE 26-14. Three-dimensional imaging. (A) A linear transducer produces parallel scan lines

and rectangular display; linear scan. (B) A curve “phase array” transducer results in a curvilinear

scan and an arch-shaped image. (C) An example of cross-sectional three-dimensional (3D) imaging.

(D) An example of longitudinal 3D imaging. Three-dimensional imaging theoretically should provide

more spatial orientation of the image structures; however, its current drawback is lower resolution

and greater complexity compared with 2D images, which limit its application in the current practice

of regional anesthesia.

Time-Gain Compensation

The echoes exhibit a steady decline in amplitude with increasing depth. This occurs for two reasons:

First, each successive reflection removes a certain amount of energy from the pulse, decreasing the

generation of later echoes. Second, tissue absorbs ultrasound, so there is a steady loss of energy as

the ultrasound pulse travels through the tissues. This can be corrected by manipulating time-gain

compensation (TGC) and compression functions.

Amplification is the conversion of the small voltages received from the transducer into larger ones

that are suitable for further processing and storage. Gain is the ratio of output to input electric power.

TGC is time-dependent exponential amplification. TGC function can be used to increase the

amplitude of incoming signals from various tissue depths. The layout of the TGC controls varies from

one machine to another. A popular design is a set of slider knobs; each knob in the slider set controls

the gain for a specific depth, which allows for a well-balanced gain scale on the image (Figure 26-

15A–C). Compression is the process of decreasing the differences between the smallest and largest

echo-voltage amplitudes; the optimal compression is between 2 and 4 for maximal scale equal to 6.

FIGURE 26-15. (A–C) The effect of the time-gain compensation settings. Time-gain compensation is

a function that allows time (depth) dependent amplification of signals returning from different depths.

SCM-sternocleidomastoid muscle, IJV-Internal jugular vein, N-nerve, CA-carotid artery, Th-thyroid

gland.

Focusing

As previously discussed, it is common to use an electronic means to narrow the width of the beam at

some depth and achieve a focusing effect similar to that obtained using a convex lens (Figure 26-16).

This strategy improves the resolution in the plane because the beam width is converged. However, the

reduction in beam width at the selected depth is achieved at the expense of degradation in beam width

at other depths, resulting in poorer images below the focal region.

FIGURE 26-16. A demonstration of focusing effect. An electronic means can be used to narrow the

width of the beam at specific depth resulting in the focusing effect and a greater resolution at a chosendepth.

Bioeffect and Safety

The mechanisms of action by which ultrasound application could produce a biologic effect can be

characterized into two aspects: heating and mechanical. The generation of heat increases as

ultrasound intensity or frequency is increased. For similar exposure conditions, the expected

temperature increase in bone is significantly greater than in soft tissues. Reports in animal models

(mice and rats) suggest that application of ultrasound may result in a number of undesired effects, suchas fetal weight reduction, postpartum mortality, fetal abnormalities, tissue lesions, hind limb

paralysis, blood flow stasis, and tumor regression. Other reported undesired effects in mice are

abnormalities in B-cell development and ovulatory response, and teratogenicity. In general, adult

tissues are more tolerant of rising temperature than fetal and neonatal tissues. A modern ultrasound

machine displays two standard indices: thermal and mechanical. The thermal index (TI) is defined as

the transducer acoustic output power divided by the estimated power required to raise tissue

temperature by 1°C. Mechanical index (MI) is equal to the peak rarefactional pressure divided by the

square root of the center frequency of the pulse bandwidth. TI and MI indicate the relative likelihood

of thermal and mechanical hazard in vivo, respectively. Either TI or MI >1.0 is hazardous.

Biologic effect due to ultrasound also depends on tissue exposure time. Fortunately, ultrasoundguided nerve block requires the use of only low TI and MI values on the patient for a short period of

time. Based on in vitro and in vivo experimental study results to date, there is no evidence that the useof diagnostic ultrasound in routine clinical practice is associated with any biologic risks.

SUGGESTED READING

Edelman SK. Understanding Ultrasound Physics. 3d ed. Woodlands, TX: ESP; 2004.

Hedrick WR, Hykes DL, Starchman DE. Ultrasound Physics and Instrumentation. 4th ed. Chicago, IL:

Mosby Yearbook; 2004.

Kapral S, Krafft P, Eibenberger K, Fitzgerald R, Gosch M, Weinstabl C. Ultrasound-guided

supraclavicular approach for regional anesthesia of the brachial plexus. Anesth Analg 1994; 78:507-

513.

La Grange PDP, Foster PA, Pretorius LK. Application of the Doppler ultrasound bloodflow detector in

supraclavicular brachial plexus block. Br J Anesth. 1978;50:965-967.

Marhofer P, Greher M, Kapral S. Ultrasound guidance in regional anaesthesia. Br J Anesth. 2005;94:7-

17.

O’Neill JM. Musculoskeletal Ultrasound: Anatomy and Technique. New York, NY: Springer; 2008.

Ting PL, Sivagnanaratnam V. Ultrasonographic study of the spread of local anaesthetic during axillary

brachial plexus block. Br J Anesth. 1978;63:326-329.

Zagzebski JA. Essentials of Ultrasound Physics. St. Louis, MO: Mosby; 1996.

Chapter 27 Optimizing an Ultrasound Image

Daquan Xu

Optimizing an image produced by ultrasound is an essential skill for performance of an ultrasoundguided nerve block. Anatomically, peripheral nerves are often located in the vicinity of an artery or

between muscle layers. The echo texture of normal peripheral nerves can have a hyperechoic,

hypoechoic, or honeycomb pattern (Figure 27-1). Several scanning steps and techniques can be used

to facilitate adequate nerve imaging, including the selection of sonographic modes, adjustment of

function keys, needle visualization, and interpretation of image artifacts.

FIGURE 27-1. Architecture of peripheral nerves.

All in all, sonographic imaging modes used for ultrasound-guided regional anesthesia and medical

diagnostics are conventional imaging, compound imaging, and tissue harmonic imaging (THI). The

conventional imaging is generated by a single-element angle beam. The compound imaging is

implemented by acquiring several (usually three to nine) overlapping frames from different

frequencies or from different angles. The tissue harmonic imaging acquires the information from

harmonic frequencies generated by ultrasound beam transmission through tissue, which improves

tissue contrast by suppression of scattering signals. Compound imaging with The tissue harmonic

imaging can provide images with better resolution, penetration, and interfaces and margin

enhancement, compared with those obtained using conventional sonography. In Figure 27-2,

compound imaging and conventional imaging was used to view the interscalene brachial plexus.

There is a clear margin definition of two hypoechoic oval-shaped nerve structures in compound

imaging. As an example, the contrast resolution between the anterior scalene muscle and the

surrounding adipose tissue is enhanced in comparison with those made with conventional imaging

techniques.

FIGURE 27-2. Examples of image quality typically obtained with conventional versus compound

imaging.

Five function keys on an ultrasound machine are of crucial importance to achieve an optimal image

during the performance of peripheral nerve imaging (Figure 27-3A).

FIGURE 27-3. Optimizing an ultrasound image using five key functional adjustments (A) and specific

tips on adjusting the focus (B) and gain (C). Some ultrasound models are specifically optimized for

regional anesthesia application and may not incorporate user-adjustable focus and/or time gain

compensation (TGC).

. Depth: The depth of the nerve is the first consideration when ultrasound-guided nerve block is

performed. The depth at which peripheral nerves are positioned and therefore imaged greatly varies

and also depends on a patient’s habitus. An optimal depth setting is important for proper focusing

properties during imaging. Table 27-1 describes the recommended initial depth settings for common

peripheral nerves. The target nerve should be at the center of the ultrasound image to obtain the best

resolution of the nerve and reveal other anatomic structures in the vicinity of the nerve. For example,

ultrasound imaging during supraclavicular or infraclavicular brachial plexus blockade requires that

first rib and pleura are viewed simultaneously to decrease the risk of lung puncture with the needle.

TABLE 27-1 Suggested Optimal Imaging Depth for Common Peripheral Nerve Blocks

. Frequency: The ultrasound transducer with the optimal frequency range should be selected to best

visualize the target nerves. Ultrasound energy is absorbed gradually by the transmitted tissue; the

higher the frequency of ultrasound, the more rapid the absorption, and the less distance propagation.

Therefore, a low-frequency transducer is used to scan structures at a deeper location. Unfortunately,

this is at the expense of reduced image resolution.

. Focusing: Lateral resolution can be improved by choosing the higher frequency as well as by

focusing the ultrasound beam. In actual practice, the focus is adjusted at the level of the target nerve;

the best image quality for a given nerve is obtained by choosing an appropriate frequency transducer

and the focal zone (Figure 27-3B).

. Gain: Screen brightness can be adjusted manually by two function buttons: gain and time-gain

compensation (TGC). Excessive or inadequate gain can cause both a blurring of tissue boundaries and

a loss of information. Optimal gain for scanning peripheral nerves is typically the gain at which the

best contrast is obtained between the muscles and the adjacent connective tissue. This is because

muscles are well-vascularized tissue invested with connective tissue fibers, whereas, the echo texture

of connective tissue is similar to that of nerves. In addition, increasing gain below the focus works

well with the TGC control to visualize both the target nerve and the structures below it. Figure 27-3C

shows the same section with both correct and incorrect gain and TGC settings.

. Doppler: In regional anesthesia, Doppler ultrasound is used to detect vascular structures or the

location of the spread of the local anesthetic injection. Doppler velocity is best set between 10 and 20

cm/s to reduce aliasing of color Doppler imaging and artifacts of color. Of note, power Doppler is

more sensitive for detecting blood flow than color Doppler.

Two needle insertion techniques with relevance to the needle–transducer relationship are

commonly used in ultrasound-guided nerve block: the in-plane and out-of-plane techniques (Figure

27-4). In-plane technique means the needle is placed in the plane of ultrasound beam; as a result, the

needle shaft and the tip can be observed in the longitudinal view real time as the needle is advanced

toward the target nerve. When the needle is not visualized on the image, the needle advancement

should be stopped. Tilting or rotating the transducer can bring the ultrasound beam into alignment with

the needle and help with its visualization. Additionally, a subtle, fast needle shake and or injection of

small amount of injectate may help depict the needle location. The out-of-plane technique involves

needle insertion perpendicularly to the transducer. The needle shaft is imaged in a cross-section plane

and can be identified as a bright dot in the image. Visualization of the tip of the needle, however, is

difficult and unreliable. The method used to visualize the tip of the needle is as follows: Once a bright

dot (shaft) is seen in the image, the needle can be shaken slightly and/or the transducer can be tilted

toward the direction of needle insertion simultaneously until the dot disappears. Shaking the needle

helps differentiate the echo as emanating from the needle or from the surrounding tissue. The last

capture of the hyperechoic dot is its tip. A small amount of injectate can be used to confirm the

location of needle tip. Whenever injectate is used to visualize the needle tip, attention must be paid to

avoid resistance (pressure) to injection because when the needle–nerve interface is not well seen,

there is a risk for an intraneural injection.

FIGURE 27-4. In-plane and out-of-plane needle insertion and corresponding ultrasound image.

By definition, ultrasound artifact is any image aberration that does not represent the correct

anatomic arrangement. The five artifacts often seen in regional anesthesia practice (Figure 27-5) are

as follows.

FIGURE 27-5. Common artifacts during ultrasound imaging. LA - local anesthetic, MSM - middle

scalene muscle.

. Shadowing is a significant reduction of ultrasound energy lying below solid objects (e.g., osseous

structures, gallstone). This is manifested by attenuation of the echo signals as seen in an abnormal

decrease of the brightness, which appear as a shadow on the image.

. Enhancement manifests as overly intense echogenicity behind an object (such as vessel, cyst) that is

less attenuating than the surrounding soft tissues. The echo signals are enhanced in brightness

disproportional to the echo strength. Scanning from different angles or from different planes may help

to decrease shadowing/enhancement artifacts and to visualize the target nerve.

. Reverberation is a set of equally spaced bright linear echoes behind the reflectors in the near field of

the image. It may be attenuated or eliminated when scanning direction is changed or ultrasound

frequency is decreased.

. Mirror image artifact results from an object located on one side of a highly reflective interface,

appearing on the other side as well. Both virtual and artifactual images have an equal distance to the

reflector from opposite directions. Changing scanning direction may decrease the artifact.

. Velocity error is the displacement of the interface, which is caused by the difference of actual

velocity of ultrasound in human soft tissue, compared with the calibrated speed, which is assumed to

be 1540 m/sec in the ultrasound system.

The inherent artifact in the process of scanning cannot be completely eliminated in all cases by

manipulating ultrasound devices or changing the settings. However, recognizing and understanding

ultrasound artifacts help the operator avoid misinterpretation of images.

Here is an acronym, SCANNING, for preparing to scan:

: Supplies

C: Comfortable positioning

A: Ambiance

N: Name and procedure

N: Nominate transducer

Infection control

N: Note lateral/medial side on screen

G: Gain depth

. Gather supplies: All equipment necessary for ultrasound scanning should be prepared. Equipment

may differ slightly depending on the area to be scanned; however some necessary equipment includes:

. Ultrasound machine

. Transducer covers

. Nerve block kit, nerve stimulator

. Sterile work trolley

. Local anesthetic drawn up and labeled

Whenever possible, connect the ultrasound machine to the power outlet to prevent the machine from

powering down during a procedure

. Comfortable patient position: Patient should be positioned in such a way that the patient, the

anesthesiologist, the ultrasound machine, and the sterile block tray are all arranged in an ergonomic

position that allows for a time-efficient performance of the procedure.

. The ultrasound machine should be set up on the opposite side of the patient with the screen at the

operator’s eye level.

. Block tray should be positioned close enough to the operator so it eliminates the need to reach for

needle, gel, and other supplies but should not interfere with the scanning procedure.

. Ambiance—set room settings: Adjust the lights in the room in order to view the ultrasound machine

and procedural site adequately.

. Dim lighting optimizes visualization of the image on the screen; more lighting is typically needed for

the procedural site.

. Adjust the room light settings to allow for proper lighting to both areas, as well for safe monitoring of

the patient.

. Name of patient, procedure, and site of procedure: Before performing a scan take a “time-out” to

ensure patient information is correct, the operation being done is confirmed, and the side in which the

procedure is being done is validated. Checking that patient informati on is entered into the ultrasound

machine and matches the information on the patient’s wristband not only confirms identity but also

allows for images to be saved during the scanning process for documentation.

. Select transducer: Select the transducer that best fits the scheduled procedure to be done.

. A linear transducer is best scanning superficial anatomic structures; a curved (phased array)

transducer displays a sector image and is typically better for deeper positioned structures.

. Disinfection: Disinfect the patient’s skin using a disinfectant solution to reduce the risk of

contamination and infection.

. Orient transducer and apply gel: The operator should orient the transducer to match the mediallateral orientation of the patient. This is conventionally not done by radiologists/sonographers, but it

is very useful for intervention-oriented regional anesthesia procedures.

. Touch one edge of the transducer to orient the side of the transducer so the medial-lateral orientation

on the patient corresponds to that on the screen.

. A sufficient amount of gel is applied to either the transducer or the patient’s skin to allow for

transmission of the ultrasound. A copious amount of disinfectant solution can be used instead of gel in

many instances.

. Insufficient quality of gel will decrease reflection-absorption rates and may result in unclear/blurry

images on the ultrasound image being displayed.

. Place transducer on the patient’s skin and adjust ultrasound machine settings:

. The gain should be adjusted with the general gain setting and/or by using TGC.

. The depth is adjusted to optimize imaging of structures of interest.

. Where available, focus point is adjusted at the desired level.

. Scanning mode can be switched to aid in the recognition of the structures as necessary (e.g., color

Doppler can help depict blood vessels, M-mode can distinguish between arteries and veins).

SUGGESTED READING

Chudleigh T, Thilaganathan B. Obstetric Ultrasound: How, Why and When. 3rd ed. Edinburgh, UK:

Elsevier Churchill Livingstone; 2004.

Grau T. Ultrasonography in the current practice of regional anaesthesia. Best Pract Res Clin

Anaesthesiol. 2005;19:175-200.

Gray AT. Ultrasound-guided regional anesthesia: current state of the art. Anesthesiology.

2006;104(2):368-373.

Sites BD, Brull R, Chan VW, et al. Artifacts and pitfall errors associated with ultrasound-guided

regional anesthesia. Part I: understanding the basic principles of ultrasound physics and machine

operations. Reg Anesth Pain Med. 2007;32(5):412-418.

Sites BD, Brull R, Chan VW, et al. Artifacts and pitfall errors associated with ultrasound-guided

regional anesthesia. Part II: a pictorial approach to understanding and avoidance. Reg Anesth Pain

Med. 2007;32(5):419-433.

SECTION 5

Ultrasound-Guided Nerve Blocks

Chapter 28 Ultrasound-Guided Cervical Plexus Block

Chapter 29 Ultrasound-Guided Interscalene Brachial Plexus Block

Chapter 30 Ultrasound-Guided Supraclavicular Brachial Plexus Block

Chapter 31 Ultrasound-Guided Infraclavicular Brachial Plexus Block

Chapter 32 Ultrasound-Guided Axillary Brachial Plexus Block

Chapter 33 Ultrasound-Guided Forearm Blocks

Chapter 34 Ultrasound-Guided Wrist Block

Chapter 35 Ultrasound-Guided Femoral Nerve Block

Chapter 36 Ultrasound-Guided Fascia Iliaca Block

Chapter 37 Ultrasound-Guided Obturator Nerve Block

Chapter 38 Ultrasound-Guided Saphenous Nerve Block

Chapter 39 Ultrasound-Guided Sciatic Block

Part 1: Anterior Approach

Part 2: Transgluteal and Subgluteal Approach

Chapter 40 Ultrasound-Guided Popliteal Sciatic Block

Chapter 41 Ultrasound-Guided Ankle Block

Chapter 42 Common Ultrasound-Guided Truncal and Cutaneous Blocks

Part 1: Transversus Abdominis Plane Block

Part 2: Iliohypogastric and Ilioinguinal Blocks

Part 3: Rectus Sheath Block

Part 4: Lateral Femoral Cutaneous Nerve Block

Ultrasound-Guided Cervical Plexus Block

FIGURE 28-1. Needle and transducer position to block the superficial cervical plexus using a

transverse view.

General Considerations

The goal of the ultrasound-guided technique of superficial cervical plexus block is to deposit local

anesthetic in the vicinity of the sensory branches of the nerve roots C2, C3, and C4. Advantages over

the landmark-based technique include the ability to ensure the spread of local anesthetic in the correct

plane and therefore increase the success rate and avoid too deep needle insertion and/or inadvertent

puncture of neighboring structures. Both in-plane and out-of-plane approaches can be used. The

experience with ultrasound-guided deep cervical plexus is still in its infancy and not described here.

Ultrasound Anatomy

The sternocleidomastoid muscle (SCM) forms a “roof” over the nerves of the superficial cervical

plexus (C2-4). The roots combine to form the four terminal branches (lesser occipital, greater

auricular, transverse cervical, and supraclavicular nerves) and emerge from behind the posterior

border of the SCM (Figure 28-2). The plexus can be visualized as a small collection of hypoechoic

nodules (honeycomb appearance or hypo-echoic [dark] oval structures) immediately deep or lateral

to the posterior border of the SCM (Figure 28-3), but this is not always apparent. Occasionally, the

greater auricular nerve is visualized (Figure 28-4) on the superficial surface of the SCM muscle as a

small, round hypoechoic structure. The SCM is separated from the brachial plexus and the scalene

muscles by the prevertebral fascia, which can be seen as a hyperechoic linear structure. The

superficial cervical plexus lies posterior to the SCM muscle, and immediately underneath the

prevertebral fascia overlying the interscalene groove. (Figure 28-3).

FIGURE 28-2. Anatomy of the superficial cervical plexus. sternocleidomastoid muscle.

mastoid process. clavicle. external jugular vein. Superficial cervical plexus is seen emerging

behind the posterior border of the sternocleidomastoid muscle at the intersection of the muscle with

the external jugular vein. Greater auricular nerve.

FIGURE 28-3. Superficial cervical plexus-transverse view.

FIGURE 28-4. Branches of the superficial cervical plexus (CP) emerging behind the prevertebral

fascia that covers the middle (MSM) and anterior (ASM) scalene muscles, and posterior to the

sternocleidomastoid muscle (SCM). White arrows, Prevertebral Fascia; CA, carotid artery; PhN,

phrenic nerve.

Distribution of Blockade

The superficial cervical plexus block results in anesthesia of the skin of the anterolateral neck and the

anteauricular and retroauricular areas, as well as the skin overlying and immediately inferior to the

clavicle on the chest wall (Figure 28-5).

FIGURE 28-5. Sensory distribution of the cervical plexus and innervation of the lateral aspect of the

face.

Equipment

Equipment needed includes the following:

Ultrasound machine with linear transducer (8–18 MHz), sterile sleeve, and gel

Standard nerve block tray (described in the equipment section)

Two 10-mL syringes containing local anesthetic

A 2.5-in, 23- to 25-gauge needle attached to low-volume extension tubing

Sterile gloves

Landmarks and Patient Positioning

Any patient position that allows for comfortable placement of the ultrasound transducer and needle

advancement is appropriate. This block is typically performed in the supine or semi-sitting position,

with the head turned slightly away from the side to be blocked to facilitate operator access (Figure

28-6A and B). The patient’s neck and upper chest should be exposed so that the relative length and

position of the SCM can be assessed.

FIGURE 28-6. Superficial cervical plexus block. A) Transverse approach with an in-plane needle

advancement. B) Longitudinal approach.

GOAL

The goal is to place the needle tip immediately adjacent to the superficial cervical plexus. If it is not

easily visualized, the local anesthetic can be deposited in the plane immediately deep to the SCM and

underneath the prevertebral fasica. A volume of 10 to 15 mL of local anesthetic usually suffices.

Technique

With the patient in the proper position, the skin is disinfected and the transducer is placed on the

lateral neck, overlying the SCM at the level of its midpoint (approximately the level of the cricoid

cartilage). Once the SCM is identified, the transducer is moved posteriorly until the tapering posterior

edge is positioned in the middle of the screen. At this point, an attempt should be made to identify the

brachial plexus and/or the interscalene groove between the anterior and middle scalene muscles. The

plexus is visible as a small collection of hypoechoic nodules (honeycomb appearance) immediately

underneath the prevertebral fascia that overlies the interscalene groove (Figures 28-3 and 28-4).

Once identified, the needle is passed through the skin, platysma and prevertebral fascia, and the tip

placed adjacent to the plexus (Figure 28-7). Because of the relatively shallow position of the target,

both in-plane (from medial or lateral sides) and out-of-plane approaches can be used. Following

negative aspiration, 1 to 2 mL of local anesthetic is injected to confirm the proper injection site. Then

the remainder of the local anesthetic (10–15 mL) is administered to envelop the plexus (Figure 28-8).

FIGURE 28-7. Needle path (1) and position to block the superficial cervical plexus (CP), transverse

view. The needle is seen positioned underneath the lateral border of the sternocleidomastoid muscle

(SCM) and underneath the prevertebral fascia with the transducer in a transverse position (Figure 28-

1). ASM, anterior scalene muscle; CA, carotid artery; MSM, middle scalene muscle.

FIGURE 28-8. Desired distribution of the local anesthetic (area shaded in blue) to block the

superficial cervical plexus. ASM, anterior scalene muscle; CA, carotid artery; CP, cervical plexus;

MSM, middle scalene muscle; SCM, sternocleidomastoid muscle.

If the plexus is not visualized, an alternative substernocleidomastoid approach can be used. In this

case, the needle is passed behind the SCM and the tip is directed to lie in the space between the SCM

and the prevertebral fascia, close to the posterior border of the SCM (Figures 28-6B, 28-9, and 28-

10). Local anesthetic (10–15 mL) is administered and should be visualized layering out between the

SCM and the underlying prevertebral fascia (Figure 28-11). If injection of the local anesthetic does

not appear to result in an appropriate spread, additional needle repositioning and injections may be

necessary. Because the superficial cervical plexus is made up of purely sensory nerves, high

concentrations of local anesthetic are usually not required; 0.25%-0.5% ropivacaine, bupivacaine

0.25%, or lidocaine 1% are examples of good choices.

FIGURE 28-9. Longitudinal view of the superficial cervical plexus (CP) underneath the lateral

border of the sternocleidomastoid muscle (SCM).

FIGURE 28-10. Needle position to block the cervical plexus (CP), longitudinal view.

FIGURE 28-11. Desired spread of the local anesthetic under the cervical fascia to block the cervical

plexus (CP).

TIPS

Visualization of the plexus is not necessary to perform this block because it may not be always readily

apparent. Administration of 10 to 15 mL of local anesthetic deep to the SCM provides a reliable

block without confirming the position of the plexus.

The superficial cervical plexus overlies the brachial plexus (i.e., immediately superficial to the

interscalene groove and underneath the prevertebral fascia). This can serve as a sonographic

landmark by identifying the scalene muscles, the trunks of the brachial plexus, and/or the groove itself

and the prevertebral fascia.

SUGGESTED READING

Aunac S, Carlier M, Singelyn F, De Kock M. The analgesic efficacy of bilateral combined superficial

and deep cervical plexus block administered before thyroid surgery under general anesthesia. Anesth

Analg. 2002;95:746-750.

Demondion X, Herbinet P, Boutry N, et al. Sonographic mapping of the normal brachial plexus. Am J

Neuroradiol. 2003;24:1303-1309.

Eti Z, Irmak P, Gulluoglu BM, Manukyan MN, Gogus FY. Does bilateral superficial cervical plexus

block decrease analgesic requirement after thyroid surgery? Anesth Analg. 2006;102:1174-1176.

Guay J. Regional anesthesia for carotid surgery. Curr Opin Anaesthesiol. 2008;21:638-644.

Narouze S. Sonoanatomy of the cervical spinal nerve roots: implications for brachial plexus block. Reg

Anesth Pain Med. 2009;34:616.

Roessel T, Wiessner D, Heller AR, et al. High-resolution ultrasound-guided high interscalene plexus

block for carotid endarterectomy. Reg Anesth Pain Med. 2007;32:247-253.

Sandeman DJ, Griffiths MJ, Lennox AF. Ultrasound guided deep cervical plexus block. Anaesth

Intensive Care. 2006;34:240-244.

Soeding P, Eizenberg N. Review article: anatomical considerations for ultrasound guidance for regionalanesthesia of the neck and upper limb. Can J Anaesth. 2009;56:518-533.

Usui Y, Kobayashi T, Kakinuma H, Watanabe K, Kitajima T, Matsuno K. An anatomical basis for

blocking of the deep cervical plexus and cervical sympathetic tract using an ultrasound-guided

technique. Anesth Analg. 2010;110:964-968.

Ultrasound-Guided Interscalene Brachial Plexus Block

FIGURE 29-1. Ultrasound-guided interscalene brachial plexus block; transducer and needle position

to obtain the desired ultrasound image for an in-plane approach.

General Considerations

The ultrasound-guided technique of interscalene brachial plexus block differs from nerve stimulator

or landmark-based techniques in several important aspects. Most importantly, distribution of the local

anesthetic is visualized to assure adequate spread around the brachial plexus. Ultrasound guidance

allows multiple injections around the brachial plexus, therefore eliminating the reliance on a single

large injection of local anesthetic for block success as is the case with non–ultrasound-guided

techniques. Ability to inject multiple aliquots of local anesthetic also may allow for the reduction in

the volume of local anesthetic required to accomplish the block. Repetition of the block in case of

inadequate anesthesia is also possible, a management option that is unpredictable without ultrasound

guidance. Finally, the risk of major vessel and nerve puncture during nerve block performance is

reduced.

Ultrasound Anatomy

The brachial plexus at the interscalene level is seen lateral to the carotid artery, between the anterior

and middle scalene muscles (Figures 29-2, 29-3, and 29-4). Prevertebral fascia, superficial cervical

plexus and sternocleidomastoid muscle are seen superficial to the plexus. The transducer is moved in

the superior-inferior direction until two or more of the brachial plexus trunks are seen in the space

between the scalene muscles. Depending on the depth of field selected and the level at which the

scanning is performed, first rib and/or apex of the lung may be seen. The brachial plexus is typically

visualized at a depth of 1 to 3 cm.

FIGURE 29-2. Relevant anatomy for interscalene brachial block and transducer position to obtain

the desired views. Brachial plexus (BP) is seen sandwiched between middle scalene muscle (MSM)

laterally and anterior scalene muscle (ASM) medially. Ultrasound image often includes a partial view

of the lateral border of the sternocleidomastoid muscle (SCM) as well as the internal jugular vein

(IJV) and carotid artery (CA). The transverse process of one of the cervical vertebrae is also often

seen.

FIGURE 29-3. Interscalene brachial plexus is seen between middle scalene muscle and anterior

scalene muscle. Carotid artery is seen medial at 1 cm depth in this image.

FIGURE 29-4. Typical image of the brachial plexus (BP). The BP is seen positioned between the

anterior scalene muscle (ASM) and the middle scalene muscle (MSM). The superficial cervical

plexus (white arrowhead) can be seen posterior to the SCM and underneath the prevertebral fascia. In

this particular image, the vertebral artery (VA), carotid artery (CA), as well as the transverse process

of C6 are also seen.

Distribution of Blockade

The interscalene approach to brachial plexus blockade results in anesthesia of the shoulder and upper

arm. Inferior trunk for more distal anesthesia can also be blocked by additional, selective injection,

deeper in the plexus. This is accomplished either by controlled needle redirection inferiorly or by

additional scanning to visualize the inferior trunk and another needle insertion and targeted injection.

For a more comprehensive review of the brachial plexus distribution, see Chapter 1 on Essential

Regional Anesthesia Anatomy.

Equipment

Equipment needed includes the following:

Ultrasound machine with linear transducer (8–14 MHz), sterile sleeve, and gel

Standard nerve block tray (described in the equipment section)

One 20-mL syringe containing local anesthetic

5-cm, 22-gauge short-bevel insulated stimulating needle

Peripheral nerve stimulator

Sterile gloves

Landmarks and Patient Positioning

Any position that allows comfortable placement of the ultrasound transducer and needle advancement

is appropriate. The block is typically performed with the patient in supine, semisitting, or semilateral

decubitus position, with the patient’s head facing away from the side to be blocked. The latter

position may prove ergonomically more convenient, especially during an in-plane approach from the

lateral side, in which the needle is entering the skin at the posterolateral aspect of the neck. A slight

elevation of the head of the bed is often more comfortable for the patient, and it allows for better

drainage and less prominence of the neck veins.

Adherence to strict anatomic landmarks is of lesser importance for the ultrasound-guided

interscalene block than it is the case for the surface anatomy-based techniques. Regardless,

knowledge of the underlying anatomy and the position of the brachial plexus is important to facilitate

recognition of the ultrasound anatomy. Scanning usually begins just below the level of the cricoid

cartilage and medial to the sternocleidomastoid muscle with a goal to identify the carotid artery.

GOAL

The goal is to place the needle in the tissue space between the anterior and middle scalene muscles

and inject local anesthetic until the spread around the brachial plexus is documented by ultrasound.

The volume of the local anesthetic and number of needle insertions are determined during the

procedure and depend on the adequacy of the observed spread of the local anesthetic.

Technique

With the patient in the proper position, the skin is disinfected and the transducer is positioned in the

transverse plane to identify the carotid artery (Figure 29-5). Once the artery is identified, the

transducer is moved slightly laterally across the neck (see algorithm at end of chapter). The goal is to

identify the scalene muscles and the brachial plexus that is sandwiched between the anterior and

middle scalene muscles.

FIGURE 29-5. Ultrasound image just below the level of the cricoid cartilage and medial to the

sternocleidomastoid muscle. ASM, anterior scalene muscle; SCM, sternocleidomastoid muscle; IJV,

internal jugular vein; CA, carotid artery; Th, thyroid gland.

TIP

When the visualization of the brachial plexus between the scalene muscles proves difficult, the

transducer is lowered to the supraclavicular fossa. At this position, the brachial plexus is identified

lateral and superficial to the subclavian artery, (Figure 29-6). From here, the brachial plexus is

traced cranially to the desired level.

FIGURE 29-6. View of the brachial plexus (BP) at the supraclavicular fossa. When identification of

the brachial plexus at the interscalene level proves difficult, the transducer is positioned at the

supraclavicular fossa to identify the BP superficial and lateral to the subclavian artery (SA). The

transducer is then slowly moved cephalad while continuously visualizing the brachial plexus until the

desired level is reached.

The needle is then inserted in-plane toward the brachial plexus, typically in a lateral-to-medial

direction (Figure 29-7), although medial-to-lateral needle orientation also can be chosen if more

convenient. As the needle passes through the prevertebral fascia, a certain “give” is often

appreciated. When nerve stimulation is used (0.5 mA, 0.1 msec), the entrance of the needle in the

interscalene groove is often associated with a motor response of the shoulder, arm, or forearm as

another confirmation of the proper needle placement. After a careful aspiration to rule out an

intravascular needle placement, 1 to 2 mL of local anesthetic is injected to document the proper

needle placement (Figure 29-8A). Injection of several milliliters of local anesthetic often displaces

the brachial plexus away from the needle. An additional advancement of the needle 1 to 2 mm toward

the brachial plexus may be beneficial to assure a proper spread of the local anesthetic (Figure 29-

8B). Whenever the needle is further advanced, or multiple injections used, assure that high resistance

to injection is absent to decrease the risk of an intrafascicular injection. When injection of the local

anesthetic does not appear to result in a spread around the brachial plexus, additional needle

repositions and injections may be necessary.

FIGURE 29-7. (A) Transducer placement and needle insertion. (B) Position of the needle (1) for the

interscalene brachial plexus block using an in-plane approach. The needle tip is seen in contact with

the superior trunk of the brachial plexus (yellow arrows); this always results in high injection

pressure (>15 psi)—indicating that the needle should be withdrawn slightly away from the trunk.

FIGURE 29-8. (A) A small amount of local anesthetic (blue shaded area) is injected through the

needle to confirm the proper needle placement. A properly placed needle tip will result in

distribution of the local anesthetic between and/or alongside roots of the brachial plexus (BP). (B) An

actual needle (white arrowhead) placement in the interscalene groove with the dispersion of the local

anesthetic (LA; blue shaded area or arrows) surrounding the BP.

TIPS

• The presence of the motor response to nerve stimulation is useful but not necessary to elicit if the

plexus, needle, and local anesthetic spread are well-visualized.

• The neck is a very vascular area, and care must be exercised to avoid needle placement or

injection into the vascular structures. Of particular importance is to avoid the vertebral artery, and

branches of the thyrocervical trunk: inferior thyroid artery, suprascapular artery, and transverse

cervical artery.

• Never inject against high resistance (>15 psi) because this may indicate a needle-nerve contact or

an intrafascicular injection.

• Pro and con of multiple injections:

Pro: May increase the speed of onset and success rate of the interscalene block.

Pro: May allow for a reduction in the total volume and dose of local anesthetic required to

accomplish block.

Con: May carry a higher risk of nerve injury because part of the plexus may be anesthetized by

the time consecutive injections are made.

NOTE: Avoidance of high resistance to injection and needle–nerve contact is essential to avoid

intrafascicular injection because reliance on nerve stimulation with multiple injections is

diminished.

In an adult patient, 15 to 25 mL of local anesthetic is usually adequate for successful and rapid

onset of blockade. Smaller volumes of local anesthetics can also be effective, however, their success

rate in everyday clinical practice may be inferior to those reported in meticulously conducted clinical

trials. The block dynamics and perioperative management are similar to those described in Chapter

12.

Continuous Ultrasound-Guided Interscalene Block

The goal of the continuous interscalene block is similar to the non–ultrasound-based techniques: to

place the catheter in the vicinity of the trunks of the brachial plexus between the scalene muscles. The

procedure consists of three phases: needle placement, catheter advancement, and securing of the

catheter. For the first two phases of the procedure, ultrasound can be used to assure accuracy. The

needle is typically inserted in-plane from the lateral-to-medial direction and underneath the

prevertebral fascia to enter the interscalene space (Figure 29-9), although other needle directions

could be used.

FIGURE 29-9. Continuous brachial plexus block. Needle is inserted in the interscalene space using

an in-plane approach. Please note that for better demonstration, sterile drapes are not used in the

model in this figure.

TIP

Both stimulating and nonstimulating catheters can be used, although for simplicity we prefer

nonstimulating catheters for ultrasound-guided continuous interscalene block.

Proper placement of the needle can also be confirmed by obtaining a motor response of the deltoid

muscle, arm, or forearm (0.5 mA, 0.1 msec) at which point 4 to 5 mL of local anesthetic can be

injected. This small dose of local anesthetic serves to assure adequate distribution of the local

anesthetic as well as to make the advancement of the catheter more comfortable to the patient. This

first phase of the procedure does not significantly differ from the single-injection technique. The

second phase of the procedure involves maintaining the needle in the proper position and inserting the

catheter 2 to 3 cm into the interscalene space in the vicinity of the brachial plexus (Figure 29-10).

Insertion of the catheter can be accomplished by a single operator or with a helper. Proper location of

the catheter can be determined either by visualizing the course of the catheter or by an injection of the

local anesthetic through the catheter. When this proves difficult, alternatively, a small amount of air (1

mL) can be injected to confirm the catheter tip location.

FIGURE 29-10. An ultrasound image demonstrating needle and catheter (white arrow) inserted in the

interscalene space between the anterior (ASM) and middle (MSM) scalene muscles. BP, brachial

plexus.

There is no agreement on what constitutes the ideal catheter securing system. The catheter is

secured by either taping to the skin or tunneling. Some clinicians prefer one over the other. However,

the decision about which method to use could be based on the patient’s age, duration of the catheter

therapy, and anatomy. Tunneling could be preferred in older patients with obesity or mobile skin over

the neck and when longer duration of catheter infusion is expected. Two main disadvantages of

tunneling are the risk of catheter dislodgment during the tunneling and the potential for scar formation.

Fortunately, a number of catheter-securing devices are available to help stabilize the catheter.

SUGGESTED READING

Single Injection UG-IS block

redrickson MJ, Ball CM, Dalgleish AJ. Posterior versus anterolateral approach interscalene catheter

placement: a prospective randomized trial. Reg Anesth Pain Med. 2011;36:125-33.

redrickson MJ, Ball CM, Dalgleish AJ, Stewart AW, Short TG. A prospective randomized

comparison of ultrasound and neurostimulation as needle end points for interscalene catheter

placement. Anesth Analg. 2009;108:1695-700.

redrickson MJ, Kilfoyle DH. Neurological complication analysis of 1000 ultrasound guided

peripheral nerve blocks for elective orthopaedic surgery: a prospective study. Anaesthesia. 2009;

64:836-44.

Gadsden J, Hadzic A, Gandhi K, Shariat A, Xu D, Maliakal T, Patel V. The effect of mixing 1.5%

mepivacaine and 0.5% bupivacaine on duration of analgesia and latency of block onset in ultrasoundguided interscalene block. Anesth Analg. 2011;112:471-6.

Koff MD, Cohen JA, McIntyre JJ, Carr CF, Sites BD. Severe brachial plexopathy after an ultrasoundguided single-injection nerve block for total shoulder arthroplasty in a patient with multiple sclerosis.

Anesthesiology. 2008;108:325-8.

Liu SS, Gordon MA, Shaw PM, Wilfred S, Shetty T, Yadeau JT. A prospective clinical registry of

ultrasound-guided regional anesthesia for ambulatory shoulder surgery. Anesth Analg. 2010;111:617-

23.

Liu SS, YaDeau JT, Shaw PM, Wilfred S, Shetty T, Gordon M. Incidence of unintentional intraneural

injection and postoperative neurological complications with ultrasound-guided interscalene and

supraclavicular nerve blocks. Anaesthesia. 2011;66:168-74.

Marhofer P, Harrop-Griffiths W, Willschke H, Kirchmair L. Fifteen years of ultrasound guidance in

regional anaesthesia: Part 2-recent developments in block techniques. Br J Anaesth. 2010;104:673-

83.

McNaught A, Shastri U, Carmichael N, Awad IT, Columb M, Cheung J, Holtby RM, McCartney CJ.

Ultrasound reduces the minimum effective local anaesthetic volume compared with peripheral nerve

stimulation for interscalene block. Br J Anaesth. 2011;106:124-30.

Orebaugh SL, McFadden K, Skorupan H, Bigeleisen PE. Subepineurial injection in ultrasound-guided

interscalene needle tip placement. Reg Anesth Pain Med. 2010;35:450-4.

Renes SH, van Geffen GJ, Rettig HC, Gielen MJ, Scheffer GJ.Minimum effective volume of local

anesthetic for shoulder analgesia by ultrasound-guided block at root C7 with assessment of pulmonary

function. Reg Anesth Pain Med. 2010;35:529-34.

pence BC, Beach ML, Gallagher JD, Sites BD. Ultrasound-guided interscalene blocks: understanding

where to inject the local anaesthetic. Anaesthesia. 2011;66:509-14.

Continuous US-IS Block

Antonakakis JG, Sites BD, Shiffrin J. Ultrasound-guided posterior approach for the placement of a

continuous interscalene catheter. Reg Anesth Pain Med. 2009;34:64-8.

redrickson MJ, Ball CM, Dalgleish AJ. Analgesic effectiveness of a continuous versus single-

injection interscalene block for minor arthroscopic shoulder surgery. Reg Anesth Pain Med.

2010;35:28-33.

Fredrickson MJ, Price DJ. Analgesic effectiveness of ropivacaine 0.2% vs 0.4% via an ultrasoundguided C5-6 root/ superior trunk perineural ambulatory catheter. Br J Anaesth. 2009;103:434-9.

Mariano ER, Afra R, Loland VJ, Sandhu NS, Bellars RH, Bishop ML, Cheng GS, Choy LP, Maldonado

RC, Ilfeld BM. Continuous interscalene brachial plexus block via an ultrasound-guided posterior

approach: a randomized, triple-masked, placebo-controlled study. Anesth Analg. 2009;108:1688-94.

Mariano ER, Loland VJ, Ilfeld BM. Interscalene perineural catheter placement using an ultrasoundguided posterior approach. Reg Anesth Pain Med. 2009;34:60-3.

Ultrasound-Guided Supraclavicular Brachial Plexus Block

FIGURE 30-1. Supraclavicular brachial plexus; transducer position and needle insertion.

General Considerations

The proximity of the brachial plexus at this location to the chest cavity and pleura, has been of

concern to many practitioners (Figure 30-2). However, ultrasound guidance has resulted in a

resurgence of interest in the supraclavicular approach to the brachial plexus. The ability to image the

plexus, rib, pleura, and subclavian artery with ultrasound guidance has increased safety due to better

monitoring of anatomy and needle placement. Because the trunks and divisions of the brachial plexus

are relatively close as they travel over the first rib, the onset and quality of anesthesia is fast and

complete. For these reasons, the supraclavicular block has become a popular technique for surgery

below the shoulder.

FIGURE 30-2. Anatomy of the supraclavicular brachial plexus with proper transducer placement

slightly obliquely above the clavicle (Cl). SA, subclavian artery; arrow, brachial plexus (BP).

Ultrasound Anatomy

The subclavian artery crosses over the first rib between the insertions of the anterior and middle

scalene muscles, at approximately the midpoint of the clavicle. The pulsating subclavian artery is

readily apparent, whereas the parietal pleura and the first rib can be seen as a linear hyperechoic

structure immediately lateral and deep to it, respectively (Figure 30-3). The rib, as an osseous

structure, casts an acoustic shadow, so that the image field deep to the rib appears anechoic, or dark.

A reverberation artifact (refer to Chapter 26) often occurs, mimicking a second subclavian artery

beneath the rib. The brachial plexus can be seen as a bundle of hypoechoic round nodules (e.g.,

“grapes”) just lateral and superficial to the artery (Figures 30-3, 30-4, 30-5A and B). It is often

possible to see the fascial sheath enveloping the brachial plexus. Depending at the level at which the

plexus is scanned and the transducer orientation, brachial plexus can have an oval or flattened

appearance (Figure 30-5A and B). Two different sonographic appearances of the brachial plexus

(one oval and one flattened) are easily seen by changing the angle of the transducer orientation during

imaging. Lateral and medial to the first rib is the hyperechoic pleura, with lung tissue deep to it. This

structure can be confirmed by observation of a “sliding” motion of the viscera pleura with the

patient’s respiration. The brachial plexus is typically visualized at a 1- to 2-cm depth at this location,

an important anatomical characteristic of the plexus that must be kept in mind throughout the

procedure.

FIGURE 30-3. Unlabeled ultrasound image of the supraclavicular brachial plexus.

FIGURE 30-4. Supraclavicular brachial plexus (BP) is seen slightly superficial and lateral to the

subclavian artery (SA). Brachial plexus is enveloped by a tissue sheath (white arrows). Note the

intimate location of the pleura and lung to the brachial plexus and subclavian artery. Middle scalene

muscle (MSM). White arrows: Prevertebral fascia.

FIGURE 30-5. (A) Ultrasound image of the brachial plexus (BP) assuming an oval shape and circled

by the tissue sheath (yellow arrows). (B) Ultrasound image of the BP at the supraclavicular fossa

with the downward orientation of the transducer. The brachial plexus assumes a flatter configuration

as it descends underneath the clavicle into the infraclavicular fossa. SA, subclavian artery. ASM,

anterior scalene muscle.

Distribution of Blockade

The supraclavicular approach to the brachial plexus blockade results in anesthesia of the upper limb

below the shoulder because all trunks and divisions can be anesthetized. The medial skin of the upper

arm (intercostobrachial nerve, T2), however, is never anesthetized by any technique of the brachial

plexus block and when needed can be blocked by an additional subcutaneous injection just distal to

the axilla. For a more comprehensive review of the brachial plexus anatomy and distribution, see

Chapter 1, Essential Regional Anesthesia Anatomy.

Equipment

Equipment needed includes the following:

Ultrasound machine with linear transducer (8–14 MHz), sterile sleeve, and gel (or other coupling

medium; e.g. saline)

Standard nerve block tray (described in Chapter 3)

20 to 25 mL local anesthetic

5-cm, 22-gauge short-bevel insulated stimulating needle

Peripheral nerve stimulator

Sterile gloves

Landmarks and Patient Positioning

Any position that allows comfortable placement of the ultrasound transducer and needle advancement

is appropriate. This block can be performed with the patient in the supine, semi-sitting (our favorite),

or slight oblique position, with the patient’s head turned away from the side to be blocked. When

possible, asking the patient to reach for the ipsilateral knee will depress the clavicle slightly and

allow better access to the structures of the anterolateral neck. Also, a slight elevation of the head of

the bed is often more comfortable for the patient and allows for better drainage and less prominence

of the neck veins (Figure 30-1).

Adherence to strict anatomic landmarks is of lesser importance for the ultrasound-guided

supraclavicular block than for the surface anatomy techniques. However, knowledge of the underlying

anatomy and the position of the brachial plexus in relation to the subclavian artery, first rib, and

pleura are important for the success and safety of the technique. Scanning is usually started just above

the clavicle at approximately its midpoint.

GOAL

The goal is to place the needle in the brachial plexus sheath in the vicinity of the subclavian artery

and inject local anesthetic until the spread within the brachial plexus is documented by observing the

centrifugal displacement of the trunks and divisions on the ultrasound.

Technique

With the patient in the proper position (we prefer semi-sitting position), the skin is disinfected and the

transducer is positioned in the transverse plane immediately superior to the clavicle at approximately

its midpoint. The transducer is tilted caudally to obtain a cross-sectional view of the subclavian

artery (Figures 30-6). The brachial plexus is seen as a collection of hypoechoic oval structures

lateral and superficial to the artery.

FIGURE 30-6. Supraclavicular brachial plexus; transducer position and needle insertion.

TIP

To achieve the best possible view, the transducer often must be tilted slightly inferiorly, rather than

perpendicular to the skin. The goal is to see the artery as a pulsating circular structure (transverse

view), rather than an oval or linear structure.

Using a 25- to 27-gauge needle, 1 to 2 mL of local anesthetic is injected into the skin 1 cm lateral

to the transducer to decrease the discomfort during needle insertion. Local infiltration may not be

necessary in well premedicated patients. The needle should never be inserted deeper than 1 cm to

avoid inadvertent puncture of and injection into the brachial plexus. Always observe the distribution

of the local anesthetic during administration by injecting small amounts of the local anesthetic as the

needle advances through tissue layers (hydro-localization). The block needle is then inserted in-plane

toward the brachial plexus, in a lateral-to-medial direction (Figures 30-6 and 30-7). When nerve

stimulation is used (0.5 mA, 0.1 msec), the entrance of the needle into the brachial plexus sheath is

often associated with a palpable “pop” as the needle passes through the paravertebral fascia/brachial

plexus sheath. In addition, a motor response of the arm, forearm, or hand as another confirmation of

the proper needle placement. Note, however, that motor response may be absent despite the adequate

needle placement. Tilting the needle slightly within the plexus and/or increasing the current intensity

(e.g., 1.0–1.5 mA) will bring about the motor response, if required. After a careful aspiration, 1 to 2

mL of local anesthetic is injected to document the proper needle placement. When the injection

displaces the brachial plexus away from the needle, an additional advancement of the needle 1 to 2

mm deeper may be required to accomplish adequate spread of the local anesthetic (Figures 30-8, 30-

9, and 30-10). When injection of the local anesthetic does not appear to result in a spread in and

around the brachial plexus, additional needle repositioning and injections may be necessary. The

required volume of local anesthetic should not be premeditated but rather determined based on the

adequacy of the spread. In our practice, 20 to 25 mL is the most common total volume used.

FIGURE 30-7. Supraclavicular brachial plexus. Needle path and two separate injections required

for block of the supraclavicular brachial plexus. Shown are two needle positions (1 and 2) used to

inject local anesthetic within the tissue sheath (arrows) containing the brachial plexus (BP).

FIGURE 30-8. Desired spread of the local anesthetic (areas shaded in blue) through two different

needle positions (1 and 2), to accomplish brachial plexus (BP) block. Local anesthetic should freely

spread within the tissue sheath resulting in separation of the BP cords.

FIGURE 30-9. Supraclavicular brachial plexus (BP) with an actual needle passing the tissue sheath

surrounding brachial plexus. Needle is seen within the BP, although its tip is not visualized. Injection

at this location often results in deterioration of the ultrasound image; reliance on additional

monitoring (injection pressure, nerve stimulation) to avoid intrafascicular injection is essential.

FIGURE 30-10. Proper dispersion of the local anesthetic (LA; blue arrows after its injection within

the tissue sheath containing the brachial plexus (BP).

TIPS

• The presence of the motor response to nerve stimulation is useful but not necessary to elicit if the

plexus, needle, and local anesthetic spread are well visualized.

• The neck is a very vascular area and care must be exercised to avoid needle placement or

injection into the vascular structures. Of particular importance is to note the intimately located

internal jugular vein, inferior carotid artery, subclavian artery and the dorsal scapular artery which

often crosses the supraclavicular brachial plexus at this level. The use of color Doppler before

needle placement and injection is suggested.

• Never inject against high resistance (>15 psi) to injection because this may signal an

intrafascicular injection.

• Multiple injections:

May increase the speed of onset and success rate.

May allow for a reduction in the required volume of local anesthetic.

May carry a higher risk of nerve injury because part of the plexus may be anesthetized by the

previous injections.

In an adult patient, 20 to 25 mL of local anesthetic is usually adequate for successful and rapid

onset of blockade; however, when necessary, higher volumes may be used. Some clinicians

recommend injecting a single bolus at the point where the subclavian artery meets the first rib. This is

thought to “float” the plexus superficially and result in more reliable blockade of the inferior

divisions of the plexus. However, we do not find this useful or safe (risk of pleura puncture); instead

it is always beneficial to inject two to three smaller aliquots at different locations within the plexus

sheath to assure spread of the local anesthetic solution in all planes containing brachial plexus. In our

program, we simply administer two aliquots of local anesthetics at two separate locations within the

plexus sheath as seen in Figure 30-8. The block dynamics and perioperative management are similar

to those described in Chapter 13.

Continuous Ultrasound-Guided Supraclavicular Block

The ultrasound-guided continuous supraclavicular block is in many ways similar to the technique for

interscalene catheter placement. The goal is to place the catheter in the vicinity of the trunks/divisions

of the brachial plexus adjacent to the subclavian artery. The procedure consists of three phases:

needle placement, catheter advancement, and securing of the catheter. For the first two phases of the

procedure, ultrasound can be used to assure accuracy in most patients. The needle is typically

inserted in-plane from the lateral-to-medial direction so that the tip is just lateral to the brachial

plexus sheath. The needle is then advanced to indent and transverse the sheath, followed by placement

of the catheter.

TIP

When the needle approaches the brachial plexus, extra force is required to penetrate the prevertebral

fascia and enter the brachial plexus “sheath”. The entrance of the needle into the sheath is always

associated with a distinct “pop” sensation as the needle breaches the fascial layer.

Proper placement of the needle can also be confirmed by obtaining a motor response of the arm,

forearm, or hand, at which point 4–5 mL of local anesthetic is injected. This small dose of local

anesthetic serves to assure adequate distribution of the local anesthetic as well as to make the

advancement of the catheter more comfortable to the patient. This first phase of the procedure does

not significantly differ from the single-injection technique. The second phase of the procedure

involves maintaining the needle in the proper position and inserting the catheter 2 to 3 cm into the

sheath of the brachial plexus (Figure 30-11 shows the preloaded needle with the catheter). Care must

be taken not to advance the catheter too far, which may result in the catheter exiting the brachial

plexus and the consequent failure to provide analgesia. Insertion of the catheter can be accomplished

by either a single operator or a with a helper.

FIGURE 30-11. A needle insertion for the continuous supraclavicular brachial plexus block. The

catheter is inserted 3–5 cm beyond the needle tip and injected with 3–5 mL of local anesthetic to

document the proper dispersion of the local anesthetic within the brachial plexus sheath.

The catheter is secured by either taping to the skin or tunneling. Some clinicians prefer one over

the other. The decision about which method to use could be based on the patient’s age, duration of the

catheter therapy, and anatomy. Tunneling could be preferred in older patients with obesity or mobile

skin over the neck and longer planned duration of the catheter infusion. Two main disadvantages of

the tunneling are the risk of catheter dislodgment during the tunneling and the potential for scar

formation. A number of devices are commercially available to help secure the catheter. The starting

infusion regimen is typically 5 mL/hour of 0.2% ropivacaine with 5-mL patient-controlled boluses

hourly.

SUGGESTED READING

Aguirre J, Ekatodramis G, Ruland P, Borgeat A: Ultrasound-guided supraclavicular block: is it really

safer? Reg Anesth Pain Med. 2009;34:622.

Arcand G, Williams SR, Chouinard P, et al. Ultrasound-guided infraclavicular versus supraclavicular

block. Anesth Analg. 2005;101:886-890.

Beach ML, Sites BD, Gallagher JD. Use of a nerve stimulator does not improve the efficacy of

ultrasound-guided supraclavicular nerve blocks. J Clin Anesth. 2006;18:580-584.

Bigeleisen PE, Moayeri N, Groen GJ. Extraneural versus intraneural stimulation thresholds during

ultrasound-guided supraclavicular block. Anesthesiology. 2009;110:1235-1243.

Chan VW, Perlas A, Rawson R, Odukoya O. Ultrasound-guided supraclavicular brachial plexus block.

Anesth Analg. 2003;97:1514-1517.

Chin KJ, Niazi A, Chan V. Anomalous brachial plexus anatomy in the supraclavicular region detected

by ultrasound. Anesth Analg. 2008;107:729-731.

Chin KJ, Singh M, Velayutham V, Chee V. Infraclavicular brachial plexus block for regional

anaesthesia of the lower arm. Cochrane Database Syst Rev. 2010;2:CD005487.

Chin J, Tsui BC. No change in impedance upon intravascular injection of D5W. Can J Anaesth.

2010;57:559-564.

Collins AB, Gray AT, Kessler J. Ultrasound-guided supraclavicular brachial plexus block: a modified

Plumb-Bob technique. Reg Anesth Pain Med. 2006;31:591-592.

Cornish P. Supraclavicular block—new perspectives. Reg Anesth Pain Med. 2009;34:607-608.

Cornish PB, Leaper CJ, Nelson G, Anstis F, McQuillan C, Stienstra R. Avoidance of phrenic nerve

paresis during continuous supraclavicular regional anaesthesia. Anaesthesia. 2007;62:354-358.

Duggan E, Brull R, Lai J, Abbas S. Ultrasound-guided brachial plexus block in a patient with multiple

glomangiomatosis. Reg Anesth Pain Med. 2008;33:70-73.

Duggan E, El Beheiry H, Perlas A, et al. Minimum effective volume of local anesthetic for ultrasoundguided supraclavicular brachial plexus block. Reg Anesth Pain Med. 2009;34:215-218.

redrickson MJ, Kilfoyle DH. Neurological complication analysis of 1000 ultrasound guided

peripheral nerve blocks for elective orthopaedic surgery: a prospective study. Anaesthesia.

2009;64:836-844.

redrickson MJ, Patel A, Young S, Chinchanwala S. Speed of onset of ‘corner pocket supraclavicular’

and infraclavicular ultrasound guided brachial plexus block: a randomised observer-blinded

comparison. Anaesthesia. 2009;64:738-744.

Gupta PK, Pace NL, Hopkins PM. Effect of body mass index on the ED50 volume of bupivacaine 0.5%

for supraclavicular brachial plexus block. Br J Anaesth. 2010;104:490-495.

Hebbard PD. Artifactual mirrored subclavian artery on ultrasound imaging for supraclavicular block.

Can J Anaesth. 2009;56:537-538.

eon DG, Kim WI. Cases series: ultrasound-guided supraclavicular block in 105 patients. Korean J

Anesthesiol. 2010;58:267-271.

Kapral S, Krafft P, Eibenberger K, Fitzgerald R, Gosch M, Weinstabl C. Ultrasound-guided

supraclavicular approach for regional anesthesia of the brachial plexus. Anesth Analg. 1994;78:507-

513.

Klaastad O, Sauter AR, Dodgson MS. Brachial plexus block with or without ultrasound guidance. Curr

Opin Anaesthesiol. 2009;22:655-660.

a Grange P, Foster PA, Pretorius LK. Application of the Doppler ultrasound bloodflow detector in

supraclavicular brachial plexus block. Br J Anaesth. 1978;50:965-967.

Lasserre A, Tran-Van D, Gaertner E, Labadie P, Fontaine B: Ultrasound guided locoregional

anaesthesia: realization and diagnosis of complications [in French]. Ann Fr Anesth Reanim.

2009;28:584-587.

Macfarlane AJ, Perlas A, Chan V, Brull R. Eight ball, corner pocket ultrasound-guided supraclavicular

block: avoiding a scratch. Reg Anesth Pain Med. 2008;33:502-503.

Manickam BP, Oosthuysen SA, Parikh MK. Supraclavicular brachial plexus block-variant relation of

brachial plexus to subclavian artery on the first rib. Reg Anesth Pain Med. 2009;34:383-384.

Marhofer P, Schrogendorfer K, Koinig H, Kapral S, Weinstabl C, Mayer N. Ultrasonographic guidance

improves sensory block and onset time of three-in-one blocks. Anesth Analg. 1997;85:854-857.

Morfey D, Brull R. Ultrasound-guided supraclavicular block: What is intraneural? Anesthesiology.

2010;112:250-251.

Morfey DH, Brull R. Finding the corner pocket: landmarks in ultrasound-guided supraclavicular block.

Anaesthesia. 2009;64:1381.

Neal JM, Moore JM, Kopacz DJ, Liu SS, Kramer DJ, Plorde JJ. Quantitative analysis of respiratory,

motor, and sensory function after supraclavicular block. Anesth Analg. 1998;86:1239-1244.

erlas A, Chan VW, Simons M. Brachial plexus examination and localization using ultrasound and

electrical stimulation: a volunteer study. Anesthesiology. 2003;99:429-435.

erlas A, Lobo G, Lo N, Brull R, Chan VW, Karkhanis R. Ultrasound-guided supraclavicular block:

outcome of 510 consecutive cases. Reg Anesth Pain Med. 2009;34:171-176.

lunkett AR, Brown DS, Rogers JM, Buckenmaier CC 3rd. Supraclavicular continuous peripheral

nerve block in a wounded soldier: when ultrasound is the only option. Br J Anaesth. 2006;97:715-

717.

Renes SH, Spoormans HH, Gielen MJ, Rettig HC, van Geffen GJ. Hemidiaphragmatic paresis can be

avoided in ultrasound-guided supraclavicular brachial plexus block. Reg Anesth Pain Med. 2009;

34:595-599.

amet R, Villamater E. Eight ball, corner pocket for ultrasound-guided supraclavicular block: high risk

for a scratch. Reg Anesth Pain Med. 2008;33:87.

horthouse JR, Danbury CM. Ultrasound-guided supraclavicular brachial plexus block in Klippel-Feil

syndrome. Anaesthesia. 2009;64:693-694.

oares LG, Brull R, Lai J, Chan VW. Eight ball, corner pocket: the optimal needle position for

ultrasound-guided supraclavicular block. Reg Anesth Pain Med. 2007;32:94-95.

Tran de QH, Munoz L, Zaouter C, Russo G, Finlayson RJ. A prospective, randomized comparison

between single- and double-injection, ultrasound-guided supraclavicular brachial plexus block. Reg

Anesth Pain Med. 2009;34:420-424.

Tran de QH, Russo G, Munoz L, Zaouter C, Finlayson RJ. A prospective, randomized comparison

between ultrasound-guided supraclavicular, infraclavicular, and axillary brachial plexus blocks. Reg

Anesth Pain Med. 2009;34:366-371.

Tsui BC, Doyle K, Chu K, Pillay J, Dillane D. Case series: ultrasound-guided supraclavicular block

using a curvilinear probe in 104 day-case hand surgery patients. Can J Anaesth. 2009;56:46-51.

Tsui BC, Twomey C, Finucane BT. Visualization of the brachial plexus in the supraclavicular region

using a curved ultrasound probe with a sterile transparent dressing. Reg Anesth Pain Med.

2006;31:182-184.

VadeBoncouer TR, Weinberg GL, Oswald S, Angelov F. Early detection of intravascular injection

during ultrasound-guided supraclavicular brachial plexus block. Reg Anesth Pain Med. 2008;33:278-279.

Williams SR, Chouinard P, Arcand G, et al. Ultrasound guidance speeds execution and improves the

quality of supraclavicular block. Anesth Analg. 2003;97:1518-1523.

Ultrasound-Guided Infraclavicular Brachial Plexus Block

FIGURE 31-1. In-plane needle insertion technique during infraclavicular brachial plexus block.

General Considerations

The ultrasound-guided infraclavicular brachial plexus block is in some ways both simple and

challenging. It is simple in the sense that geometric measuring of distances and angles on the surface

of the patient, as is the case with the nerve stimulator–based technique, is not required. Identification

of the arterial pulse on the sonographic image is an easy primary goal in establishing the landmark.

However, the plexus at this level is situated deeper, and the angle of approach is more acute, making

simultaneous visualization of the needle and the relevant anatomy more challenging. Fortunately,

although it is not always possible to reliably identify the three cords of the plexus at this position,

adequate block can be achieved by simply depositing the local anesthetic in a “U” shape around the

artery. Infraclavicular block is well-suited for catheter technique because the musculature of the chest

wall helps stabilize the catheter and prevents its dislodgment compared with the more superficial

location with the interscalene or supraclavicular approaches.

Ultrasound Anatomy

The axillary artery can be identified deep to the pectoralis major and minor muscles. An effort needs

to be made to obtain clear views of both pectoralis muscles and their respective fasciae. This is

important because the area of interest lies underneath the fascia of the pectoralis minor muscle.

Surrounding the artery are the three cords of the brachial plexus: the lateral, posterior, and medial

cords. These are named for their usual position relative to the axillary artery, although there is a great

deal of anatomic variation. With the left side of the screen corresponding to the cephalad aspect, the

cords can often be seen as round hyperechoic structures at approximately 9 o’clock (lateral cord), 7

o’clock (posterior cord), and 5 o’clock (medial cord) (Figures 31-2, 31-3, and 31-4). The axillary

vein is seen as a compressible hypoechoic structure that lies inferior, or slightly superficial, to the

axillary artery. Multiple other, smaller vessels (e.g., the cephalic vein) are often present as well. The

transducer is moved in the superior-inferior direction until the artery is identified in cross-section.

Depending on the depth of field selected and the level at which the scanning is performed, the chest

wall and lung may be seen in the inferior aspect of the image. The axillary artery and/or brachial

plexus are typically identified at a depth of 3 to 5 cm in average size patients.

FIGURE 31-2. Anatomy of the infraclavicular brachial plexus and the position of the transducer.

Brachial plexus (BP) is seen surrounding the axillary artery (AA) underneath the clavicle (Cl) and

pectoralis minor muscle (PMiM). Note that the injection of local anesthetic should take place below

the fascia of the PMiM to spread around the AA. PMaM, pectoralis major muscle.

FIGURE 31-3. Unlabeled ultrasound image of the infraclavicular fossa demonstrating pectoralis

muscles, their respective sheets, axillary (subclavian) vessels, and the chest wall.

FIGURE 31-4. Labeled ultrasound image of the brachial plexus (BP) in the infraclavicular fossa. LC,

lateral cord; PC, posterior cord; MC, medial cord. Note that the brachial plexus and the axillary

artery (AA) are located below the fascia (red line) of the pectoralis minor muscle (PMiM). PMaM,

pectoralis major muscle.

Distribution of Blockade

The infraclavicular approach to brachial plexus blockade results in anesthesia of the upper limb

below the shoulder. The medial skin of the upper arm (intercostobrachial nerve, T2), if required, can

be blocked by an additional subcutaneous injection on the medial aspect of the arm just distal to the

axilla. A simpler approach is for surgeons to infiltrate the skin with the local anesthetic directly over

the incision line, if necessary. For a more comprehensive review of the brachial plexus distribution,

see Chapter 1, Essential Regional Anesthesia Anatomy.

Equipment

Equipment needed for this block includes the following:

Ultrasound machine with linear transducer (8–14 MHz), sterile sleeve, and gel

Standard nerve block tray

20 to 30 mL of local anesthetic drawn up in syringes

8- to 10-cm long, 21-22 gauge short-bevel insulated stimulating needle

Peripheral nerve stimulator

Sterile gloves

Landmarks and Patient Positioning

Any position that allows comfortable placement of the ultrasound transducer and needle advancement

is appropriate. The block is typically performed with the patient in supine position with the head

turned away from the side to be blocked (Figure 31-5). The arm is abducted to 90° and the elbow

flexed. This maneuver reduces the depth from the skin to the plexus and substantially facilitates

visualization of the pectoralis muscles as well as the cords of the brachial plexus.

FIGURE 31-5. Patient position in needle insertion for infraclavicular brachial plexus block. The

transducer is positioned parasagittally just medial to the coracoid process and inferior to the clavicle.

The coracoid process is an important landmark and can be easily identified by palpating the bony

prominence just medial to the shoulder while the arm is elevated and lowered. As the arm is lowered,

the coracoid process meets the fingers of the palpating hand. Scanning is usually begun just medial to

the coracoid process and inferior to the clavicle. As scanning experience increases, it eventually

becomes unnecessary to identify the coracoids process before scanning.

GOAL

The goal of the technique is to inject local anesthetic until the spread around the artery is documented

by ultrasound. It is not necessary to identify and target individual cords. Instead, injection of the local

anesthetic to surround the artery in a U-shape pattern (cephalad, caudad, and posterior) suffices for

block of all three cords.

Technique

With the patient in the proper position, the skin is disinfected and the transducer is positioned in the

parasagittal plane to identify the axillary artery (Figures 31-3 and 31-4, and 31-5). This may require

adjustment of the depth, depending on the thickness of the patient’s chest wall musculature. The

axillary artery (or the transition of the subclavian to axillary artery) is typically seen between 3 and 5

cm. Once the artery is identified, an attempt is made to identify the hyperechoic cords of the brachial

plexus and their corresponding positions relative to the artery, although these may not always be

identifiable. Fortunately, exhaustive efforts to visualize the cords are not necessary for successful

blockade.

TIP

Reverberation artifact posterior to the artery is often misinterpreted as the posterior cord. Figure 31-7

demonstrate such a dilemma where the structured labeled as posterior cord (PC) can easily represent

a mere reverberation artifact.

The needle is inserted in-plane from the cephalad aspect, with the insertion point just inferior to

the clavicle (Figure 31-5). The needle is aimed toward the posterior aspect of the axillary artery and

passes through the pectoralis major and minor muscles. If nerve stimulation is used concurrently (0.5-

0.8 mA, 0.1 msec), the first motor response is often from the lateral cord (either elbow flexion or

finger flexion). As the needle is further advanced beneath the artery, a posterior cord motor response

may appear (finger and wrist extension). After careful aspiration, 1 to 2 mL of local anesthetic is

injected to confirm the proper needle placement and spread. The injectate should spread cephalad and

caudad to cover the lateral and medial cords, respectively (Figure 31-6). When injection of the local

anesthetic with a single injection does not appear to result in adequate spread, additional needle

repositions and injections around the axillary artery may be necessary (Figure 31-7).

FIGURE 31-6. Ultrasound image demonstrating an ideal needle path for the infraclavicular brachial

plexus block. Blue-shaded area mimics an ideal spread of the local anesthetic around axillary artery

(AA) and reaching all three cords of the brachial plexus (LC, PC, MC) below the fascia (red line) of

the pectoralis minor muscle. PMaM, pectoralis major muscle; PMiM, pectoralis minor muscle.

FIGURE 31-7. An ultrasound image demonstrating an actual needle placement above (cephalad) the

axillary artery (AA) and an injection of local anesthetic (2 mL; blue shadow) to document the proper

needle tip placement. LC, lateral cord; MC, medial cord; PC, posterior cord.

TIPS

• A caudad to cephalad needle insertion is also possible but may carry a higher risk of

peumothorax and venous puncture

• To decrease the risk of complications:

Aspirate every 5 mL to decrease a risk of an intravascular injection.

Do not inject if the resistance to injection is high.

Do not change the transducer pressure throughout the injection (this can “open and close” veins

in the area and possibly increase the risk of an intravascular injection).

In an adult patient, 20 to 30 mL of local anesthetic is usually adequate for successful blockade.

Although a single injection of such large volumes of local anesthetic often suffices, it may be

beneficial to inject two to three smaller aliquots at different locations to assure spread of the local

anesthetic solution in all planes containing brachial plexus. The block dynamics and perioperative

management are similar to those described in Chapter 14.

Continuous Ultrasound-Guided Infraclavicular Block

The goal of the continuous infraclavicular block is similar to the non–ultrasound-based techniques: to

place the catheter in the vicinity of the cords of the brachial plexus beneath the pectoral muscles. The

procedure consists of three phases: needle placement, catheter advancement, and securing of the

catheter. For the first two phases of the procedure, ultrasound can be used to assure accuracy in most

patients. The needle is typically inserted in-plane from the cephalad-to-caudad direction, similar to

the single-injection technique (Figure 31-8).

FIGURE 31-8. Patient position, imaging and needle placement for continuous infraclavicular

brachial plexus block are similar to those in a single-injection technique. Once the proper needle tip

is determined by injection of a small volume of local anesthetic, the catheter is inserted 2–4 cm

beyond the needle tip.

As with the single injection technique, the needle tip should be placed posterior to the axillary

artery prior to injection and catheter advancement. Proper placement of the needle can also be

confirmed by obtaining a motor response of the posterior cord (finger or wrist flexion) at which point

1 to 2 mL of local anesthetic is injected. This small dose of local anesthetic serves to document the

proper placement of the needle tip as evidenced by adequate distribution of the local anesthetic. The

injection also may make the advancement of the catheter more comfortable to the patient. This first

phase of the procedure does not significantly differ from the single-injection technique. The second

phase of the procedure involves maintaining the needle in the proper position and advancing the

catheter 2 to 4 cm beyond the needle tip, in the vicinity of the posterior cord. Insertion of the catheter

can be accomplished by either single operator or a with a helper (Figure 31-8). A typical starting

infusion regimen is 5 mL/hour with 8-mL patient-controlled boluses every hour. The larger bolus

volume is necessary for the adequate spread of the injectate around the artery to reach all cords of the

brachial plexus. The catheter is secured by either taping to the skin or tunneling. Some clinicians

prefer one over the other. However, the decision on which method to use could be based on the

patient’s age, duration of the catheter therapy, and anatomy. Tunneling could be preferred in older

patients with obesity or mobile skin over the neck and longer planned duration of the catheter

infusion. One advantage to catheter placement with the infraclavicular approach is that the pectoralis

muscles tend to stabilize the catheter and prevent dislodgment.

SUGGESTED READING

Aguirre J, Baulig B, Borgeat A. Does ultrasound-guided infraclavicular block meet users’ expectations?

Can J Anaesth. 2010;57:176-177.

Akyildiz E, Gurkan Y, Caglayan C, Solak M, Toker K. Single vs. double stimulation during a lateral

sagittal infraclavicular block. Acta Anaesthesiol Scand. 2009;53:1262-1267.

Arcand G, Williams SR, Chouinard P, et al. Ultrasound-guided infraclavicular versus supraclavicular

block. Anesth Analg. 2005;101:886-890.

Bigeleisen P, Wilson M. A comparison of two techniques for ultrasound guided infraclavicular block.

Br J Anaesth. 2006;96:502-507.

Bigeleisen PE. Ultrasound-guided infraclavicular block in an anticoagulated and anesthetized patient.

Anesth Analg. 2007;104:1285-1287.

Bloc S, Garnier T, Komly B, et al. Spread of injectate associated with radial or median nerve-type

motor response during infraclavicular brachial-plexus block: an ultrasound evaluation. Reg Anesth

Pain Med. 2007;32:130-135.

Bowens C Jr, Gupta RK, O’Byrne WT, Schildcrout JS, Shi Y, Hawkins JJ, Michaels DR, Berry JM.

Selective local anesthetic placement using ultrasound guidance and neurostimulation for

infraclavicular brachial plexus block. Anesth Analg. 2010;110:1480-5.

Bowens C Jr, Gupta RK, O’Byrne WT, et al. Selective local anesthetic placement using ultrasound

guidance and neurostimulation for infraclavicular brachial plexus block. Anesth Analg.

2010;110:1480-1485.

Brull R, Lupu M, Perlas A, Chan VW, McCartney CJ. Compared with dual nerve stimulation,

ultrasound guidance shortens the time for infraclavicular block performance. Can J Anaesth.

2009;56:812-818.

Brull R, McCartney CJ, Chan VW. A novel approach to infraclavicular brachial plexus block: the

ultrasound experience. Anesth Analg. 2004;99:950.

Chin KJ, Singh M, Velayutham V, Chee V. Infraclavicular brachial plexus block for regional

anaesthesia of the lower arm. Cochrane Database Syst Rev 2010;2:CD005487.

Chin KJ, Singh M, Velayutham V, Chee V. Infraclavicular brachial plexus block for regional

anaesthesia of the lower arm. Anesth Analg. 2010;111:1072.

Desgagnes MC, Levesque S, Dion N, et al. A comparison of a single or triple injection technique for

ultrasound-guided infraclavicular block: a prospective randomized controlled study. Anesth Analg.

2009;109:668-672.

De Tran QH, Bertini P, Zaouter C, Munoz L, Finlayson RJ. A prospective, randomized comparison

between single- and double-injection ultrasound-guided infraclavicular brachial plexus block. Reg

Anesth Pain Med. 2010;35:16-21.

Dhir S, Ganapathy S. Use of ultrasound guidance and contrast enhancement: a study of continuous

infraclavicular brachial plexus approach. Acta Anaesthesiol Scand. 2008;52:338-342.

Dhir S, Ganapathy S. Comparative evaluation of ultrasound-guided continuous infraclavicular brachial

plexus block with stimulating catheter and traditional technique: a prospective-randomized trial. Acta

Anaesthesiol Scand. 2008;52:1158-1166.

Dhir S, Singh S, Parkin J, Hannouche F, Richards RS. Multiple finger joint replacement and continuous

physiotherapy using ultrasound guided, bilateral infraclavicular catheters for continuous bilateral

upper extremity analgesia. Can J Anaesth. 2008;55:880-881.

Dingemans E, Williams SR, Arcand G, et al. Neurostimulation in ultrasound-guided infraclavicular

block: a prospective randomized trial. Anesth Analg. 2007;104:1275-1280.

Dolan J. Ultrasound-guided infraclavicular nerve block and the cephalic vein. Reg Anesth Pain Med.

2009;34:528-529.

Dolan J. Fascial planes inhibiting the spread of local anesthetic during ultrasound-guided

infraclavicular brachial plexus block are not limited to the posterior aspect of the axillary artery. Reg

Anesth Pain Med. 2009;34:612-613.

redrickson MJ, Wolstencroft P, Kejriwal R, Yoon A, Boland MR, Chinchanwala S. Single versus

triple injection ultrasound-guided infraclavicular block: confirmation of the effectiveness of the

single injection technique. Anesth Analg. 2010;111:1325-7.

redrickson MJ, Patel A, Young S, Chinchanwala S. Speed of onset of ’corner pocket supraclavicular’

and infraclavicular ultrasound guided brachial plexus block: a randomised observer-blinded

comparison. Anaesthesia. 2009;64:738-744.

Gurkan Y, Acar S, Solak M, Toker K. Comparison of nerve stimulation vs. ultrasound-guided lateral

sagittal infraclavicular block. Acta Anaesthesiol Scand. 2008;52:851-855.

Gurkan Y, Ozdamar D, Hosten T, Solak M, Toker K. Ultrasound guided lateral sagital infraclavicular

block for pectoral flap release. Agri. 2009;21:39-42.

Gurkan Y, Tekin M, Acar S, Solak M, Toker K. Is nerve stimulation needed during an ultrasoundguided lateral sagittal infraclavicular block? Acta Anaesthesiol Scand. 2010;54:403-407.

iang XB, Zhu SZ, Jiang Y, Chen QH, Xu XZ. Optimal dose of local anesthetic mixture in ultrasoundguided infraclavicular brachial plexus block via coracoid approach: analysis of 160 cases [in

Chinese]. Zhonghua Yi Xue Za Zhi. 2009;89:449-452.

Koscielniak-Nielsen ZJ, Frederiksen BS, Rasmussen H, Hesselbjerg L. A comparison of ultrasoundguided supraclavicular and infraclavicular blocks for upper extremity surgery. Acta Anaesthesiol

Scand. 2009;53:620-626.

Koscielniak-Nielsen ZJ, Rasmussen H, Hesselbjerg L. Pneumothorax after an ultrasound-guided lateral

sagittal infraclavicular block. Acta Anaesthesiol Scand. 2008;52:1176-1177.

Levesque S, Dion N, Desgagne MC. Endpoint for successful, ultrasound-guided infraclavicular brachial

plexus block. Can J Anaesth. 2008;55:308.

Marhofer P, Harrop-Griffiths W, Willschke H, Kirchmair L. Fifteen years of ultrasound guidance in

regional anaesthesia: Part 2-recent developments in block techniques. Br J Anaesth. 2010;104:673-

683.

Mariano ER, Loland VJ, Bellars RH, et al. Ultrasound guidance versus electrical stimulation for

infraclavicular brachial plexus perineural catheter insertion. J Ultrasound Med. 2009;28:1211-1218.

Martinez Navas A, DE LA Tabla Gonzalez RO. Ultrasound-guided technique allowed early detection of

intravascular injection during an infraclavicular brachial plexus block. Acta Anaesthesiol Scand.

2009;53:968-970.

Moayeri N, Renes S, van Geffen GJ, Groen GJ. Vertical infraclavicular brachial plexus block: needle

redirection after elicitation of elbow flexion. Reg Anesth Pain Med. 2009;34:236-241.

Morimoto M, Popovic J, Kim JT, Kiamzon H, Rosenberg AD. Case series: Septa can influence local

anesthetic spread during infraclavicular brachial plexus blocks. Can J Anaesth. 2007;54:1006-1010.

Nadig M, Ekatodramis G, Borgeat A. Ultrasound-guided infraclavicular brachial plexus block. Br J

Anaesth. 2003;90:107-108.

Ootaki C, Hayashi H, Amano M. Ultrasound-guided infraclavicular brachial plexus block: an

alternative technique to anatomical landmark-guided approaches. Reg Anesth Pain Med.

2000;25:600-604.

erlas A, Chan VW, Simons M. Brachial plexus examination and localization using ultrasound and

electrical stimulation: a volunteer study. Anesthesiology. 2003;99:429-435.

onde VC, Diwan S. Does ultrasound guidance improve the success rate of infraclavicular brachial

plexus block when compared with nerve stimulation in children with radial club hands? Anesth

Analg. 2009;108:1967-1970.

orter JM, McCartney CJ, Chan VW. Needle placement and injection posterior to the axillary artery

may predict successful infraclavicular brachial plexus block: a report of three cases. Can J Anaesth.

2005;52:69-73.

unj J, Joshi A, Darlong V, Pandey R. Ultrasound characteristics of spread during infraclavicular

plexus block. Reg Anesth Pain Med. 2009;34:73.

Renes S, Clark L, Gielen M, Spoormans H, Giele J, Wadhwa A. A simplified approach to vertical

infraclavicular brachial plexus blockade using hand-held Doppler. Anesth Analg. 2008;106:1012-

1014.

Ruiz A, Sala X, Bargallo X, Hurtado P, Arguis MJ, Carrera A. The influence of arm abduction on the

anatomic relations of infraclavicular brachial plexus: an ultrasound study. Anesth Analg.

2009;108:364-366.

ahin L, Gul R, Mizrak A, Deniz H, Sahin M, Koruk S, Cesur M, Goksu S. Ultrasound-guided

infraclavicular brachial plexus block enhances postoperative blood flow in arteriovenous fistulas. J

Vasc Surg. 2011; Feb 28.

andhu NS, Capan LM. Ultrasound-guided infraclavicular brachial plexus block. Br J Anaesth.

2002;89:254-259.

andhu NS, Maharlouei B, Patel B, Erkulwater E, Medabalmi P. Simultaneous bilateral infraclavicular

brachial plexus blocks with low-dose lidocaine using ultrasound guidance. Anesthesiology.

2006;104:199-201.

andhu NS, Sidhu DS, Capan LM. The cost comparison of infraclavicular brachial plexus block by

nerve stimulator and ultrasound guidance. Anesth Analg. 2004;98:267-268.

auter AR, Dodgson MS, Stubhaug A, Halstensen AM, Klaastad O. Electrical nerve stimulation or

ultrasound guidance for lateral sagittal infraclavicular blocks: a randomized, controlled, observerblinded, comparative study. Anesth Analg. 2008;106:1910-1915.

auter AR, Smith HJ, Stubhaug A, Dodgson MS, Klaastad O. Use of magnetic resonance imaging to

define the anatomical location closest to all three cords of the infraclavicular brachial plexus. Anesth

Analg. 2006;103:1574-1576.

later ME, Williams SR, Harris P, et al. Preliminary evaluation of infraclavicular catheters inserted

using ultrasound guidance: through-the-catheter anesthesia is not inferior to through-the-needle blocks.Reg Anesth Pain Med. 2007;32:296-302.

Taboada M, Rodriguez J, Amor M, et al. Is ultrasound guidance superior to conventional nerve

stimulation for coracoid infraclavicular brachial plexus block? Reg Anesth Pain Med. 2009;34:357-

360.

Tedore TR, YaDeau JT, Maalouf DB, et al. Comparison of the transarterial axillary block and the

ultrasound-guided infraclavicular block for upper extremity surgery: a prospective randomized trial.

Reg Anesth Pain Med. 2009;34:361-365.

Tran de QH, Dugani S, Dyachenko A, Correa JA, Finlayson RJ. Minimum effective volume of

lidocaine for ultrasound-guided infraclavicular block. Reg Anesth Pain Med. 2011;36:190-4.

Tran de QH, Clemente A, Tran DQ, Finlayson RJ. A comparison between ultrasound-guided

infraclavicular block using the “double bubble” sign and neurostimulation-guided axillary block.

Anesth Analg. 2008;107:1075-1078.

Tran de QH, Russo G, Munoz L, Zaouter C, Finlayson RJ. A prospective, randomized comparison

between ultrasound-guided supraclavicular, infraclavicular, and axillary brachial plexus blocks. Reg

Anesth Pain Med. 2009;34:366-371.

Ultrasound-Guided Axillary Brachial Plexus Block

FIGURE 32-1. Transducer position and needle insertion in ultrasound-guided axillary brachial

plexus block.

General Considerations

The axillary brachial plexus block offers several advantages over the other approaches to the brachial

plexus. The technique is relatively simple to perform, and may be associated with a relatively lower

risk of complications as compared with interscalene (e.g., spinal cord or vertebral artery puncture) or

supraclavicular brachial plexus block (e.g., pneumothorax). In clinical scenarios in which access to

the upper parts of the brachial plexus is difficult or impossible (e.g, local infection, burns, indwelling

venous catheters), the ability to anesthetize the plexus at a more distal level may be important. The

axillary brachial plexus block is also relatively simple to perform with ultrasound because of its

superficial location. Although individual nerves can usually be identified in the vicinity of the axillary

artery, this is not necessary because the deposition of local anesthetic around the axillary artery is

sufficient for an effective block.

Ultrasound Anatomy

The structures of interest are superficial (1–3 cm), and the pulsating axillary artery can be identified

usually within a centimeter of the skin surface on the anteromedial aspect of the proximal arm, Figure

32-2. The artery can be associated with one or more axillary veins, often located medially to the

artery. Importantly, an undue pressure with the transducer during imaging may obliterate the veins,

rendering veins invisible and prone to puncture with the needle if care is not taken to avoid it.

Surrounding the axillary artery are three of the four principal branches of the brachial plexus: the

median (superficial and lateral to the artery), the ulnar (superficial and medial to the artery), and the

radial (posterior and lateral or medial to the artery) nerves (Figure 32-2). These are seen as round

hyperechoic structures, and although the previously mentioned locations relative to the artery are

frequently encountered, there is considerable anatomic variation from individual to individual,. Three

muscles surround the neurovascular bundle: the biceps brachii (lateral and superficial), the wedgeshaped coracobrachialis (lateral and deep), and the triceps brachii (medial and posterior). The fourth

principal nerve of the brachial plexus, the musculocutaneous nerve, is found in the fascial layers

between biceps and coracobrachialis muscles, though its location is variable and can be seen within

either muscle. It is usually seen as a hypoechoic flattened oval with a bright hyperechoic rim. Moving

the transducer proximally and distally along the long axis of the arm, the musculocutaneous nerve will

appear to move toward or away from the neurovascular bundle in the fascial plane between the two

muscles. Refer to Chapter 1, Essential Regional Anesthesia Anatomy for additional information on the

anatomy of the axillary brachial plexus and its branches.

FIGURE 32-2. Cross-sectional anatomy of the axillary fossa and the transducer position to image the

brachial plexus. The brachial plexus (BP) is seen scattered around the axillary artery and enclosed in

the adipose tissue compartment containing BP, axillary artery (AA), and axillary vein (AV). MCN,

musculocutaneous nerve.

Distribution of Blockade

The axillary approach to brachial plexus blockade (including musculocutaneous nerve) results in

anesthesia of the upper limb from the midarm down to and including the hand. The axillary nerve

itself is not blocked because it departs from the posterior cord high up in the axilla. As a result, the

skin over the deltoid muscle is not anesthetized. With nerve stimulator and landmark-based

techniques, the blockade of the musculocutaneous is often unreliable, leading to a lack of blockade on

the lateral side of the forearm and wrist. This problem is remedied easily with the ultrasound-guided

approach because the musculocutaneous nerve is readily apparent and reliably anesthetized. When

required, the medial skin of the upper arm (intercostobrachial nerve, T2) can be blocked by an

additional subcutaneous injection just distal to the axilla, if required. For a more comprehensive

review of the brachial plexus distribution, see Chapter 1.

Equipment

Equipment needed includes the following:

Ultrasound machine with linear transducer (8–14 MHz), sterile sleeve, and gel

Standard nerve block tray (described in the equipment section)

Syringes with local anesthetic (20–25 mL)

4-cm, 22-gauge short-bevel insulated stimulating needle

Peripheral nerve stimulator

Sterile gloves

Landmarks and Patient Positioning

The axillary brachial plexus block requires access to the axilla. Therefore abduction of the arm 90° is

an appropriate position that allows for transducer placement and needle advancement, as well as

patient comfort (Figure 32-3). Care should be taken not to overabduct the arm because that may cause

discomfort as well as produce tension on the brachial plexus, theoretically making it more vulnerable

to needle or injection injury during the block procedure.

FIGURE 32-3. Patient position and insertion of the needle for ultrasound-guided (in plane) axillary

brachial plexus block. All needle redirections except occasionally for the musculocutaneous nerve

are done through the same needle insertion site. Seldom, another insertion of the needle is made to

block the musculocutaneous nerve.

The pectoralis major muscle is palpated as it inserts onto the humerus, and the transducer is placed

on the skin immediately distal to that point perpendicular to the axis of the arm. The starting point

should result in part of the transducer overlying both the biceps and the triceps muscles (i.e., on the

medial aspect of the arm). Sliding the transducer across the axilla will bring the axillary artery and

brachial plexus into view, if not readily apparent.

GOAL

The goal is to deposit local anesthetic around the axillary artery. Sometimes, a single injection is

sufficient to spread in a “doughnut” shape around the artery; more commonly, two or three injections

are required. In addition, an aliquot of local anesthetic should be injected adjacent to the

musculocutaneous nerve.

Technique

With the patient in the proper position, the skin is disinfected and the transducer is positioned in the

short axis orientation to identify the axillary artery (Figure 32-4A about 1 to 3 cm from the skin

surface. Once the artery is identified, an attempt is made to identify the hyperechoic median, ulnar,

and radial nerves (Figure 32-4B). However, these may not be always well seen on an ultrasound

image. Frequently present, a reverberation artifact deep to the artery is often misinterpreted for the

radial nerve. Pre-scanning should also reveal the position of the musculocutaneous nerve, in the plane

between the coracobrachialis and biceps muscles (a slight proximal-distal movement of the

transducer is often required to bring this nerve into view) (Figure 32-5).

FIGURE 32-4. (A,B) Median (MN), ulnar (UN), and radial (RN) nerves are seen scattered around

the axillary artery with the tissue sheath (white-appearing tissue fasciae around the artery) containing

nerves and axillary vessels. The musculocutaneous nerve (MCN) is seen between the biceps and

coracobrachialis (CBM) away from the rest of the brachial plexus. AA, axillary artery.

FIGURE 32-5. Musculocutaneous nerve (MCN) is seen approximately 3 cm from the axillary

neurovascular bundle (around AA). MCN in this image is positioned between the biceps and

coracobrachialis muscles (CBM). MCN must be blocked with a separate injection of local anesthetic

for a complete axillary brachial plexus block.

The needle is inserted in-plane from the cephalad aspect (Figures 32-1 and 32-3) and directed

toward the posterior aspect of the axillary artery (Figure 32-6).

FIGURE 32-6. Needle insertions for axillary brachial plexus block. Axillary brachial block can be

accomplished by two to four separate injections (1–4) to accomplish a block of the entire brachial

plexus. MCN, musculocutaneous nerve; RN, radial nerve; MN, median nerve; UN, ulnar nerve.

As nerves and vessels are positioned together in the neurovascular bundle by adjacent

musculature, advancement of the needle through the axilla may require careful hydrodissection with a

small amount of local anesthetic or other injectate. This technique involves the injection of 0.5 to 2

mL, which “peels apart” the plane in which the needle tip is continuously inserted. The needle is then

advanced a few millimeters and more injectate is administered.

Local anesthetic should be deposited posterior to the artery first, to avoid displacing the structures

of interest deeper and obscuring the nerves, which is often the case if the median or ulnar nerves are

injected first. Once 5 to 10 mL is administered, the needle is withdrawn almost to the level of the

skin, redirected toward the median and ulnar nerves, and a further 10 to 15 mL is injected in these

areas to complete the circle around the artery. The described sequence of injection is demonstrated in

Figure 32-7.

FIGURE 32-7. An image demonstrating the ideal distribution patterns of local anesthetic spread after

three separate injections (1–3) to surround the axillary artery with local anesthetic and block the

radial nerve (RN), median nerve (MN), and ulnar nerve (UN). Musculocutaneous nerve (MCN) is

blocked with a separate injection (4) because it is often outside the axillary neurovascular tissue

sheath. AA, axillary artery.

Finally, the needle is once again withdrawn to the biceps and redirected toward the

musculocutaneous nerve. Once adjacent to the nerve (stimulation will result in elbow flexion), 5 to 7

mL of local anesthetic is deposited.

In an adult patient, 20 to 25 mL of local anesthetic is usually adequate for successful blockade.

Complete spread around the artery is necessary for success but infrequently seen with a single

injection. Two to three redirections and injections are usually necessary for reliable blockade, as

well as a separate injection to block the musculocutaneous nerve. The block dynamics and

perioperative management are similar to those described in Chapter 15.

TIPS

• Frequent aspiration and slow administration of local anesthetic are critical to decrease the risk of

an intravascular injection.

Cases of systemic toxicity have been reported after apparently straightforward ultrasoundguided axillary brachial plexus blocks.

Keep the pressure applied on the transducer steady to avoid opening and closing of the multitude

of veins in the axilla and reduce the risk of an intravascular injection.

Continuous Ultrasound-Guided Axillary Block

The continuous axillary catheter is a useful technique for analgesia and a sympathetic block, such as

following finger reimplantation surgery. The goal of the continuous axillary block is similar to the

non–ultrasound-based techniques: to place the catheter in the vicinity of the branches of the brachial

plexus (i.e., within the “sheath” of the brachial plexus). The procedure consists of three phases—(1)

needle placement, (2) catheter advancement, and (3) securing of the catheter. For the first two phases

of the procedure, ultrasound can be used to assure accuracy in most patients. The needle is typically

inserted in plane from the cephalad-to-caudad direction, just as in the single-injection technique

(Figure 32-8).

FIGURE 32-8. Continuous axillary brachial plexus block is performed using a similar technique as

in the single-injection method. After injection of a small volume of local anesthetic through the needle

to document its proper placement, the catheter is advanced 2-3 cm beyond the needle tip.

After an initial injection of the local anesthetic to confirm the proper position of the needle-tip, the

catheter is inserted 2 to 3 cm beyond the needle tip. Injection is then repeated through the catheter to

document adequate spread of the local anesthetic. Alternatively, the axillary artery can be visualized

in the longitudinal view and the catheter is inserted in the longitudinal plane alongside the axillary

artery 4 to 5 cm. The longitudinal approach requires a significantly greater degree of ultrasonographic

skill, yet no data exist at this time suggesting that one approach is more efficient or better than the

other one.

TIP

Tunneling of the catheter or taping on the shaved skin using transparent occlusive dressing are

commonly used methods of securing the catheter.

SUGGESTED READING

Aguirre J, Blumenthal S, Borgeat A. Ultrasound guidance and success rates of axillary brachial plexus

block—I. Can J Anaesth. 2007;54:583.

Baumgarten RK, Thompson GE. Is ultrasound necessary for routine axillary block? Reg Anesth Pain

Med. 2006;31:88-9.

Bigeleisen PE. Nerve puncture and apparent intraneural injection during ultrasound-guided axillary

block does not invariably result in neurologic injury. Anesthesiology. 2006;105:779-783.

Bruhn J, Fitriyadi D, van Geffen GJ. A slide to the radial nerve during ultrasound-guided axillary block.

Reg Anesth Pain Med. 2009;34:623; author reply 623-624.

Campoy L, Bezuidenhout AJ, Gleed RD, et al. Ultrasound-guided approach for axillary brachial plexus,

femoral nerve, and sciatic nerve blocks in dogs. Vet Anaesth Analg. 2010;37:144-153.

Casati A, Danelli G, Baciarello M, et al. A prospective, randomized comparison between ultrasound

and nerve stimulation guidance for multiple injection axillary brachial plexus block. Anesthesiology.

2007;106:992-996.

Chan VW, Perlas A, McCartney CJ, Brull R, Xu D, Abbas S. Ultrasound guidance improves success

rate of axillary brachial plexus block. Can J Anaesth. 2007;54:176-182.

Christophe JL, Berthier F, Boillot A, et al. Assessment of topographic brachial plexus nerves variations

at the axilla using ultrasonography. Br J Anaesth. 2009;103:606-612.

Clendenen SR, Riutort K, Ladlie BL, Robards C, Franco CD, Greengrass RA. Real-time threedimensional ultrasound-assisted axillary plexus block defines soft tissue planes. Anesth Analg.

2009;108:1347-1350.

Dibiane C, Deruddre S, Zetlaoui PJ. A musculocutaneous nerve variation described during ultrasoundguided axillary nerve block. Reg Anesth Pain Med. 2009;34:617-618.

Dolan J, McKinlay S. Early detection of intravascular injection during ultrasound-guided axillary

brachial plexus block. Reg Anesth Pain Med. 2009;34:182.

Dufour E, Laloe PA, Culty T, Fischler M. Ultrasound and neurostimulation-guided axillary brachial

plexus block for resection of a hemodialysis fistula aneurysm. Anesth Analg. 2009;108:1981-1983.

Errando CL, Pallardo MA, Herranz A, Peiro CM, de Andres JA. Bilateral axillary brachial plexus

block guided by multiple nerve stimulation and ultrasound in a multiple trauma patient [in Spanish].

Rev Esp Anestesiol Reanim. 2006;53:383-386.

Gray AT. The conjoint tendon of the latissimus dorsi and teres major: an important landmark for

ultrasound-guided axillary block. Reg Anesth Pain Med. 2009;34:179-180.

Gray AT, Schafhalter-Zoppoth I. “Bayonet artifact” during ultrasound-guided transarterial axillary

block. Anesthesiology. 2005;102:1291-1292.

Gelfand HJ, Ouanes JP, Lesley MR, Ko PS, Murphy JD, Suminda SM, Isaac GR, Kumar K, Wu CL.

Analgesic efficacy of Ultrasound-guided regional anesthesia: meta-analysis. J Clin Anesth

2011;232:90-6

Hadžić A, Dewaele S, Gandhi K, Santos A. Volume and dose of local anesthetic necessary to block the

axillary brachial plexus using ultrasound guidance. Anesthesiology. 2009;111:8-9.

Harper GK, Stafford MA, Hill DA. Minimum volume of local anaesthetic required to surround each of

the constituent nerves of the axillary brachial plexus, using ultrasound guidance: a pilot study. Br J

Anaesth. 2010;104:633-636.

masogie N, Ganapathy S, Singh S, Armstrong K, Armstrong P. A prospective, randomized, doubleblind comparison of ultrasound-guided axillary brachial plexus blocks using 2 versus 4 injections.

Anesth Analg. 2010;110:1222-1226.

Liu FC, Liou JT, Tsai YF, et al. Efficacy of ultrasound-guided axillary brachial plexus block: a

comparative study with nerve stimulator-guided method. Chang Gung Med J. 2005;28:396-402.

Lo N, Brull R, Perlas A, et al. Evolution of ultrasound guided axillary brachial plexus blockade:

retrospective analysis of 662 blocks. Can J Anaesth. 2008;55:408-413.

Mannion S, Capdevila X. Ultrasound guidance and success rates of axillary brachial plexus block—II.

Can J Anaesth. 2007;54:584.

Marhofer P, Eichenberger U, Stockli S, et al. Ultrasonographic guided axillary plexus blocks with low

volumes of local anaesthetics: a crossover volunteer study. Anaesthesia. 2010;65:266-271.

Morros C, Perez-Cuenca MD, Sala-Blanch X, Cedo F: Contribution of ultrasound guidance to the

performance of the axillary brachial plexus block with multiple nerve stimulation [in Spanish]. Rev

Esp Anestesiol Reanim. 2009;56:69-74.

O’Donnell BD, Iohom G. An estimation of the minimum effective anesthetic volume of 2% lidocaine in

ultrasound-guided axillary brachial plexus block. Anesthesiology. 2009;111:25-29.

O’Donnell BD, Ryan H, O’Sullivan O, Iohom G. Ultrasound-guided axillary brachial plexus block with

20 milliliters local anesthetic mixture versus general anesthesia for upper limb trauma surgery: an

observer-blinded, prospective, randomized, controlled trial. Anesth Analg. 2009;109:279-283.

Orebaugh SL, Williams BA, Vallejo M, Kentor ML. Adverse outcomes associated with stimulatorbased peripheral nerve blocks with versus without ultrasound visualization. Reg Anesth Pain Med.

2009;34:251-255.

erlas A, Chan VW, Simons M. Brachial plexus examination and localization using ultrasound and

electrical stimulation: a volunteer study. Anesthesiology. 2003;99:429-435.

erlas A, Niazi A, McCartney C, Chan V, Xu D, Abbas S. The sensitivity of motor response to nerve

stimulation and paresthesia for nerve localization as evaluated by ultrasound. Reg Anesth Pain Med.

2006;31:445-450.

orter JM, McCartney CJ, Chan VW. Needle placement and injection posterior to the axillary artery

may predict successful infraclavicular brachial plexus block: a report of three cases. Can J Anaesth.

2005;52:69-73.

Remerand F, Laulan J, Couvret C, et al. Is the musculocutaneous nerve really in the coracobrachialis

muscle when performing an axillary block? An ultrasound study. Anesth Analg. 2010;110:1729-1734.

Robards C, Clendenen S, Greengrass R. Intravascular injection during ultrasound-guided axillary block:

negative aspiration can be misleading. Anesth Analg. 2008;107:1754-1755.

Russon K, Blanco R. Accidental intraneural injection into the musculocutaneous nerve visualized with

ultrasound. Anesth Analg. 2007;105:1504-1505.

Russon K, Pickworth T, Harrop-Griffiths W. Upper limb blocks. Anaesthesia. 2010;65(Suppl 1):48-56.

chwemmer U, Schleppers A, Markus C, Kredel M, Kirschner S, Roewer N. Operative management in

axillary brachial plexus blocks: comparison of ultrasound and nerve stimulation [in German].

Anaesthesist. 2006;55:451-456.

Sites BD, Beach ML, Spence BC, et al. Ultrasound guidance improves the success rate of a

perivascular axillary plexus block. Acta Anaesthesiol Scand. 2006;50:678-684.

Tedore TR, YaDeau JT, Maalouf DB, et al. Comparison of the transarterial axillary block and the

ultrasound-guided infraclavicular block for upper extremity surgery: a prospective randomized trial.

Reg Anesth Pain Med. 2009;34:361-365.

Tran de QH, Clemente A, Tran DQ, Finlayson RJ. A comparison between ultrasound-guided

infraclavicular block using the “double bubble” sign and neurostimulation-guided axillary block.

Anesth Analg. 2008;107:1075-1078.

Tran de QH, Russo G, Munoz L, Zaouter C, Finlayson RJ. A prospective, randomized comparison

between ultrasound-guided supraclavicular, infraclavicular, and axillary brachial plexus blocks. Reg

Anesth Pain Med. 2009;34:366-371.

Wong DM, Gledhill S, Thomas R, Barrington MJ. Sonographic location of the radial nerve confirmed

by nerve stimulation during axillary brachial plexus blockade. Reg Anesth Pain Med. 2009;34:503-

507.

Zetlaoui PJ, Labbe JP, Benhamou D. Ultrasound guidance for axillary plexus block does not prevent

intravascular injection. Anesthesiology. 2008;108:761.

Ultrasound-Guided Forearm Blocks

FIGURE 33-1. (A) Radial nerve block above the elbow. The needle is inserted in-plane from lateral

to medial direction. (B) Median nerve block at the level of the midforearm. (C) Ulnar nerve block at

the level of the midforearm.

General Considerations

Ultrasound imaging of individual nerves in the distal upper limb allows for reliable nerve blockade.

The two main indications for these blocks are a stand-alone technique for hand and/or wrist surgery

and as a means of rescuing or supplementing a patchy or failed proximal brachial plexus block. The

main advantages of the ultrasound-guided technique over the surface-based or nerve stimulator–based

techniques are the avoidance of unnecessary proximal motor and sensory blockade, that is, greater

specificity. Additional advantages are avoidance of the risk of vascular puncture and a reduction in

the overall volume of local anesthetic used. There are a variety of locations where a practitioner

could approach each of these nerves, most of which are similar in efficacy. In this chapter, we present

the approach for each nerve that we favor in our practice.

Ultrasound Anatomy

Radial Nerve

The radial nerve is best visualized above the lateral aspect of the elbow, lying in the fascia between

the brachioradialis and the brachialis muscles (Figure 33-2). The transducer is placed transversely

on the anterolateral aspect of the distal arm, 3–4 cm above the elbow crease (Figure 33-1A). The

nerve appears as a hyperechoic, triangular, or oval structure with the characteristic stippled

appearance of a distal peripheral nerve. The nerve divides just above the elbow crease into

superficial (sensory) and deep (motor) branches. These smaller divisions of the radial nerve are more

challenging to identify in the forearm; therefore, a single injection above the elbow is favored

because it ensures blockade of both. The transducer can be slid up and down the axis of the arm to

better appreciate the nerve within the musculature surrounding it. As the transducer is moved

proximally, the nerve will be seen to travel posteriorly and closer to the humerus, to lie deep to the

triceps muscles in the spiral groove (Figure 33-3).

FIGURE 33-2. (A) Radial nerve anatomy at the distal third of the humerus. (B) Sonoanatomy of the

radial nerve at the distal humerus. Radial nerve (RN) is shown between the biceps and triceps

muscles at a depth of approximately 2 cm.

FIGURE 33-3. Sonoanatomy of the radial nerve in the spiral groove of the humerus. RN, radial

nerve.

Median Nerve

The median nerve is easily imaged in the midforearm, between the flexor digitorum superficialis and

flexor digitorum profundus, where the nerve typically appears as a round or oval hyperechoic

structure (Figure 33-4A and B). The transducer is placed on the volar aspect of the arm in the

transverse orientation and tilted back and forth until the nerve is identified (Figure 33-1B). The nerve

is located in the midline of the forearm, 1–2 cm medial and deep to the pulsating radial artery. The

course of the median nerve can be traced with the transducer up and down the forearm, but as it

approaches the elbow or the wrist, its differentiation from adjacent tendons and connective tissue

becomes more challenging.

FIGURE 33-4. (A) Anatomy of the medianus nerve (MN) of the midforearm. (B) Sonoanatomy of the

MN at the midforearm. FDSM, Flexor Digitorum Superficialis Muscle; FCRM, Flexor Carpi Radialis

Muscle & PLM, Palmaris Longus Muscle; FPLM, Flexor Palmaris Longus Muscle.

Ulnar Nerve

The ulnar nerve can be easily imaged in the midforearm, immediately medial to the ulnar artery,

which acts as a useful landmark. Similar to the radial and median nerves, the ulnar nerve appears as a

hyperechoic stippled structure, with a triangular to oval shape (Figure 33-5A and B). The ulnar artery

and nerve separate, when the transducer is slid more proximally on the forearm, with the artery taking

a more lateral and deeper course. The ulnar nerve can be traced easily proximally toward the ulnar

notch, when desired, and the level of the blockade can be decided based on the desired distribution of

the anesthesia as well as the ease of imaging and accessing the nerve. Sliding the transducer distally

shows the nerve and artery becoming progressively shallower together as they approach the wrist

where the ulnar nerve lies medial to the artery.

FIGURE 33-5. (A) Anatomy of the ulnar nerve at the midforearm. The ulnar nerve (UN) is closely

related to the ulnar artery (UA). (B) Sonoanatomy of the ulnar nerve at the midforearm. UN is shown

closely related to the UA, sandwiched between the flexor carpi ulnaris (FCUM) and flexor digitorum

profundus muscles (FDPM). FDSM = Flexor Digitorum Superficialis Muscle.

Distribution of Blockade

As is the case with the landmark-based distal blocks, anesthetizing the radial, median, and/or ulnar

nerves provides sensory anesthesia and analgesia to the respective territories of the hand and wrist.

Note that the lateral cutaneous nerve of the forearm (a branch of the musculocutaneous nerve) supplies

the lateral aspect of the forearm, and it may need to be blocked separately by a subcutaneous wheal

distal to the elbow if lateral wrist surgery is planned. For a more comprehensive review of the

innervation of the hand, see Chapter 1, Essential Regional Anesthesia Anatomy.

Equipment

Equipment needed includes the following:

Ultrasound machine with linear transducer (8–14 MHz), sterile sleeve, and gel

Standard nerve block tray

One 20-mL syringe containing local anesthetic

A 2-in, 22–25 gauge short-bevel insulated stimulating needle

Peripheral nerve stimulator (optional)

Sterile gloves

TIP

Because these are superficial blocks of distal peripheral nerves, some practitioners choose to use a

small-gauge (i.e., 25-gauge) needle. When a using small-gauge needle, however, meticulous attention

should be paid to avoid an intraneural injection, which is more likely with a smaller diameter and

sharp tip design.

Landmarks and Patient Positioning

Any patient position that allows for comfortable placement of the ultrasound transducer and needle

advancement is appropriate. Typically, the block is performed with the patient in the supine position.

For the radial nerve block, the arm is flexed at the elbow and the hand is placed on the patient’s

abdomen (Figure 33-1A). This position allows for the most practical application of the transducer.

The median and ulnar nerves are blocked with the arm abducted and placed on an armboard, palm

facing up. (Figures 33-1 B, C)

Goal

The goal is to place the needle tip immediately adjacent to the nerve(s) of choice and to deposit 4–5

mL of local anesthetic in the vicinity of the nerve. It is unnecessary to completely surround the entire

nerve in a doughnut pattern, although this can enhance the speed of onset of the block. As with all

peripheral blocks, avoidance of resistance to injection is important to decrease the risk of an

intrafascicular injection.

Technique

Radial Nerve

With the patient in the proper position, the skin is disinfected and the transducer positioned so as to

identify the radial nerve. The needle is inserted in-plane, with the goal of traversing the biceps

brachii muscle and placing the tip next to the radial nerve (Figure 33-6A). If nerve stimulation is

used, a wrist or finger extension response should be elicited when the needle is in proximity to the

nerve. After negative aspiration, 4–5 mL of local anesthetic is injected (Figure 33-6B). If the spread

is inadequate, slight adjustments can be made and a further 2–3 mL of local anesthetic administered.

FIGURE 33-6. (A) Needle position to block the radial nerve (RN) at the elbow. BM - Brachialis

Muscle, BrM - Brachioradialis muscle. (B) Local anesthetic (area shaded in blue) distribution to

block the RN above the elbow. (1) Biceps brachii muscle.

Median and Ulnar Nerves

With the arm abducted and the palm up, the skin of the volar forearm is disinfected and the transducer

positioned transversely on the midforearm. The median nerve should be identified between the

previously mentioned muscle layers. If it is not immediately visualized, the transducer should be

positioned slightly more laterally and the radial artery identified, using color Doppler ultrasound.

Sliding back to the midline, the nerve can be seen approximately 1–2 cm medial and 1 cm deep to the

radial artery. The needle is inserted in-plane from either side of the transducer (Figure 33-7A). After

negative aspiration, 4–5 mL of local anesthetic is injected (Figure 33-7B). If the spread is

inadequate, slight adjustments can be made and a further 2–3 mL of local anesthetic administered.

FIGURE 33-7. (A) Needle (1) position for the block of the median nerve (MN) at the forearm. (B)

Distribution of local anesthetic for block of the MN at the forearm.

TIPS

The median nerve can often “hide” in the background of the musculature. Tilting the transducer

proximally or distally will bring the nerve out of the background.

Imaging at the level of the elbow crease readily reveals the nerve positioned medial to the brachial

artery. From this location, the nerve can be traced distally.

When in doubt, nerve stimulation (0.5-1.0 mA) can be used to confirm localization of the correct

nerve.

In some patients, the median and ulnar nerves often can both be anesthetized with a single skin

puncture.

Then the transducer is positioned more medially until the ulnar nerve is identified. The use of

color Doppler ultrasound can aid in finding the ulnar artery, which always lies lateral to the nerve at

this level. The nerve should then be traced up until the artery “splits off,” to minimize the likelihood

of arterial puncture. The needle is inserted in-plane from either side of the transducer (the lateral side

is often more ergonomic) (Figure 33-8A). After negative aspiration, 4–5 mL of local anesthetic is

injected (Figure 33-8B). If the spread of the local anesthetic is inadequate, slight adjustments can be

made and a further 2–3 mL administered.

FIGURE 33-8. (A) Needle (1) position for the block of ulnar nerve (UN) at the forearm. (B)

Distribution of local anesthetic (area shaded in blue) for the block of the UN at the forearm.

TIP

The out-of-plane approach can also be used for all three blocks; however, we find that visualizing the

needle path makes for greater consistency in placement and a lesser chance of nerve impalement.

The use of a tourniquet, either on the arm or forearm, usually requires sedation and/or additional

analgesia.

SUGGESTED READING

Eichenberger U, Stockli S, Marhofer P, et al. Minimal local anesthetic volume for peripheral nerve

block: a new ultrasound-guided, nerve dimension-based method. Reg Anesth Pain Med.

2009;34:242-246.

Gray AT, Schafhalter-Zoppoth I. Ultrasound guidance for ulnar nerve block in the forearm. Reg Anesth

Pain Med. 2003;28:335-339.

Lurf M, Leixnering M: Sensory block without a motor block: ultrasound-guided placement if pain

catheters in forearm. Acta Anaestbesiol Scand 2010;54:257-8.

Kathirgamanathan A, French J, Foxall GL, Hardman JG, Bedforth NM. Delineation of distal ulnar nerve

anatomy using ultrasound in volunteers to identify an optimum approach for neural blockade. Eur J

Anaesthesiol. 2009;26:43-46.

McCartney CJ, Xu D, Constantinescu C, Abbas S, Chan VW. Ultrasound examination of peripheral

nerves in the forearm. Reg Anesth Pain Med. 2007;32:434-439.

chafhalter-Zoppoth I, Gray AT. The musculocutaneous nerve: ultrasound appearance for peripheral

nerve block. Reg Anesth Pain Med. 2005;30:385-390.

pence BC, Sites BD, Beach ML. Ultrasound-guided musculocutaneous nerve block: a description of a

novel technique. Reg Anesth Pain Med. 2005;30:198-201.

34 Ultrasound-Guided Wrist Block

FIGURE 34-1. Ultrasound-guided wrist block. Transducer and needle positions for (A) Median

nerve block, (B) Ulnar nerve block, (C) Radial nerve block.

General Considerations

The wrist block is an effective method to provide anesthesia of the hand and fingers without the arm

immobility that occurs with more proximal brachial plexus blocks. Traditional wrist block technique

involves advancing needles using surface landmarks toward the three nerves that supply the hand,

namely the median, ulnar, and radial nerves. The ultrasound-guided approach has the advantage of

direct visualization of the needle and target nerve, which may decrease the incidence of needlerelated trauma. In addition, because the needle can be placed with precision immediately adjacent to

the nerve, smaller volumes of local anesthetic are required for successful blockade than with a blind

technique. Since the nerves are located relatively close to the surface, this is a technically easy block

to perform, but knowledge of the anatomy of the soft tissues of the wrist is essential for successful

blockade with minimum patient discomfort.

Ultrasound Anatomy

Three individual nerves are involved:

Median Nerve

The median nerve crosses the elbow medial to the brachial artery and courses toward the wrist deep

to the flexor digitorum superficialis in the center of the forearm. As the muscles taper toward tendons

near the wrist, the nerve assumes an increasingly superficial position until it is located beneath the

flexor retinaculum in the carpal tunnel with the tendons of flexor digitorum profundus, flexor

digitorum superficialis, and flexor pollicis longus. A linear transducer placed transversely at the

level of the wrist crease will reveal a cluster of oval hyperechoic structures, one of which is the

median nerve (Figures 34-2A and B and 34-3A and B). At this location it is easy to confuse the

tendons for the nerve, and vice versa; for this reason, it is recommended that the practitioner slides

the transducer 5 to 10 cm up the volar side of the forearm, leaving the tendons more distally to

confirm the location of the nerve. The tendons will have disappeared on the image, leaving just

muscle and the solitary median nerve, which then can be carefully traced back to the wrist, if desired.

In many instances, however, it is much simpler to perform a medianus block at the midforearm, where

the nerve is easier to recognize.

FIGURE 34-2. (A) Ultrasound-guided block of the median nerve at the wrist. (B) Cross-sectional

anatomy of the median nerve (MN) at the wrist.

FIGURE 34-3. (A) Cross-sectional ultrasound image of the median nerve (MN) at the wrist. (B)

Needle (1) path to reach MN at the wrist and spread of local anesthetic to block the MN.

TIP

The median nerve exhibits pronounced anisotropy. Tilting the transducer slightly will make the nerve

appear alternately brighter (more contrast) or darker (less contrast) with respect to the background.

Ulnar Nerve

The ulnar nerve is located medial (ulnar side) to the ulnar artery from the level of the midforearm to

the wrist. This provides a useful landmark. A linear transducer placed at the level of the wrist crease

will show the hyperechoic anterior surface of the ulna with shadowing behind; just lateral to the bone

and very superficial will be the triangular or oval hyperechoic ulnar nerve, with the pulsating ulnar

artery immediately next to it (Figures 34-4A and B and 34-5A and B). Unlike the median nerve, there

are fewer structures (tendons) in the immediate vicinity that can confuse identification; however, the

same confirmation scanning technique can be applied. Sliding the transducer up and down the arm

helps verify that the structure is the ulnar nerve by following the course of the ulnar artery and looking

for the nerve on its ulnar side.

FIGURE 34-4. (A) Block of the ulnar nerve (UN) at the wrist. Transducer and needle position. (B)

Transsectional anatomy of the UN at the wrist. UN is seen just medial to the ulnar artery (UA).

FIGURE 34-5. (A) Sonoanatomy of the ulnar nerve (UN) at the wrist. US, ulnar artery. (B) Needle

path to reach the UN at the wrist and approximate spread of the local anesthetic (area shaded in blue)

to anesthetize the UN.

Radial Nerve

The superficial branch of the radial nerve divides into terminal branches at the level of the wrist; for

this reason, ultrasonography is not very useful for guidance for placement of the block at the level of

the wrist. A subcutaneous field block around the area of the styloid process of the radius remains an

easy method to perform an effective radial nerve block at the level of the wrist (refer to the wrist

block in Chapter 16). However, ultrasonography can be used at the elbow level or in the midforearm.

At the level of the elbow (slightly below the elbow), the nerve is easily identified as a hyperechoic

oval or triangular structure in the layer between the brachialis (deep) and brachioradialis

(superficial) muscles lateral to the radial artery (Figures 34-6A and B and 34-7A and B).

FIGURE 34-6. (A) Block of the radial nerve (RN) at the wrist. Transducer and needle position. (B)

Cross-sectional anatomy of the RN at the wrist level. Superficial branches of the radial nerve are

highly variable at this level in number, size, and depth. For that reason, block of the RN at the wrist is

not an exact technique but rather infiltration of the local anesthetic in the subcutaneous tissue and

underneath the superficial fascia.

FIGURE 34-7. (A) Sonoanatomy of the radial nerve (RN) at the level of the wrist. (B) One branch of

the RN at the wrist is shown lateral to the radial artery (RA), and the approximate needle path to

reach a branch of the radial nerve is shown with an approximate spread of local anesthetic (area

shaded in blue) to anesthetize it.

Distribution of Blockade

A wrist block results in anesthesia of the entire hand. For a more comprehensive review of the

distribution of each terminal nerve, please see Chapter 1, Essential Regional Anesthesia Anatomy.

Equipment

Equipment needed includes the following:

Ultrasound machine with linear transducer (8–14 MHz), sterile sleeve, and gel

Standard nerve block tray (described in the equipment section)

One 20-mL syringe containing local anesthetic

A 1.5-in 22- to 25-gauge needle with low-volume extension tubing

Sterile gloves

Landmarks and Patient Positioning

The wrist block is most easily performed with the patient in the supine position to allow for the volar

surface of the wrist to be exposed. It is useful to remove splints and/or bandages on the hand to

facilitate placement of the transducer and sterile preparation of the skin surface.

Goal

The goal is to place the needle tip immediately adjacent to each of the two/three nerves to deposit

local anesthetic until its spread around the nerve is documented with ultrasound visualization.

Technique

With the arm in the proper position, the skin is disinfected. The wrist is a “tightly packed” area that is

bounded on three sides by bones. For this reason, an ultrasound-guided “wrist” block is often

performed 5 to 10 cm proximal to the wrist crease where there is more room to maneuver. For each

of the blocks, the needle can be inserted either in-plane or out-of-plane. Ergonomics often dictates

which of these is most effective. Care must be taken when performing the ulnar and radial nerve

blocks since the nerves are intimately associated with arteries. Inadvertent arterial puncture can lead

to a hematoma. Successful block is predicted by the spread of local anesthetic immediately adjacent

to the nerve. Multiple injections to achieve circumferential spread are usually not necessary because

these nerves are small and the local anesthetic diffuses quickly into the neural tissue due to the lack of

thick epineural tissues. Assuming deposition immediately adjacent to the nerve, 3 to 4 mL/nerve of

local anesthetic is sufficient to ensure an effective block.

TIP

Always assure absence of resistance to injection to decrease the risk of intrafascicular injection.

The block dynamics and perioperative management are similar to those described in Chapter 16.

SUGGESTED READING

Bajaj S, Pattamapaspong N, Middleton W, Teefey S: Ultrasound of the hand and wrist. J Hand Surg Am

2009;34:759-60.

Heinemeyer O, Reimers CD. Ultrasound of radial, ulnar, median and sciatic nerves in healthy subjects

and patients with hereditary motor and sensory neuropathies. Ultrasound Med Biol. 1999:25:481-

485.

Kiely PD, O’Farrell D, Riordan J, Harmon D: The use of ultrasound-guided hematoma blocks in wrist

fractures. J Clin Anesth 2009;21:540-2.

Liebmann O, Price D, Mills C, et al. Feasibility of forearm ultrasonography-guided nerve blocks of the

radial, ulnar, and median nerves for hand procedures in the emergency department. Ann Emerg Med

2006;48:558-562.

Macaire P, Singelyn F, Narchi P, Paqueron X. Ultrasound- or nerve stimulation-guided wrist blocks for

carpal tunnel release: a randomized prospective comparative study. Reg Anesth Pain Med.

2008;33:363-368.

McCartney CJL, Xu D, Constantinescu C, et al. Ultrasound examination of peripheral nerves in the

forearm. Reg Anesth Pain Med. 2007;32:434–439.

35 Ultrasound-Guided Femoral Nerve Block

FIGURE 35-1. Transducer position and needle insertion using an in-plane technique to block the

femoral nerve at the femoral crease.

General Considerations

The ultrasound-guided technique of femoral nerve blockade differs from nerve stimulator or

landmark-based techniques in several important aspects. Ultrasound application allows the

practitioner to monitor the spread of local anesthetic and needle placement and make appropriate

adjustments, should the initial spread be deemed inadequate. Also, because of the proximity to the

relatively large femoral artery, ultrasound may reduce the risk of arterial puncture that often occurs

with this block with the use of non-ultrasound techniques. Palpating the femoral pulse as a landmark

for the block is not required with ultrasound guidance, a process that can be challenging in obese

patients. Although the ability to visualize the needle and the relevant anatomy with ultrasound

guidance renders nerve stimulation optional, motor response obtained during nerve stimulation often

provides contributory information.

Ultrasound Anatomy

Orientation begins with the identification of the pulsating femoral artery at the level of the inguinal

crease. If it is not immediately recognized, sliding the transducer medially and laterally will bring the

vessel into view eventually. Immediately lateral to the vessel, and deep to the fascia iliaca is the

femoral nerve, which is typically hyperechoic and roughly triangular or oval in shape (Figure 35-2A

and B). The nerve is positioned in a sulcus in the iliopsoas muscle underneath the fascia iliaca. Other

structures that can be visualized are the femoral vein (medial to the artery) and occasionally the fascia

lata (superficial in the subcutaneous layer). The femoral nerve typically is visualized at a depth of 2-

to 4-cm.

FIGURE 35-2. (A) Cross-sectional anatomy of the femoral nerve (FN) at the level of the femoral

crease. FN is seen on the surface of the iliopsoas muscle covered by fascia iliaca. (white arrows).

Femoral artery (FA) and femoral vein (FV) are seen enveloped in their own vascular fascial sheath

created by one of the layers of fascia lata. (B) Sonoanatomy of the FN at the femoral triangle.

TIP

Identification of the femoral nerve often is made easier by slightly tilting the transducer cranially or

caudally. This adjustment helps “brighten” up the nerve and makes it appear distinct from the

background.

Distribution of Blockade

Femoral nerve block results in anesthesia of the anterior and medial thigh down to the knee (the knee

included), as well as a variable strip of skin on the medial leg and foot. It also contributes branches to

the articular fibers to both the hip and knee. For a more comprehensive review of the femoral nerve

distribution, see Chapter 1, Essential Regional Anesthesia Anatomy.

Equipment

Equipment needed includes the following:

Ultrasound machine with linear transducer (8–14 MHz), sterile sleeve, and gel

Standard nerve block tray (described in the equipment section)

One 20-mL syringe containing local anesthetic

A 50- to 100-mm, 22-gauge short-bevel insulated stimulating needle

Peripheral nerve stimulator

Sterile gloves

Landmarks and Patient Positioning

This block typically is performed with the patient in the supine position, with the bed or table

flattened to maximize operator access to the inguinal area. Although palpation of the femoral pulse is

a useful landmark, it is not required because the artery should be readily visualized by placing the

transducer transversely on the inguinal crease followed by slow movement laterally or medially. If

nerve stimulation is used simultaneously, exposure of the thigh and patella are required to monitor the

appropriate motor responses (patella twitch).

TIP

Exposing the inguinal region in a patient with a large abdominal pannus can be challenging. Using

a wide silk tape to retract the abdomen is a useful maneuver prior to skin preparation and scanning.

(Figure 35-3).

FIGURE 35-3. Obesity is a common problem in patients who present with an indication for femoral

nerve block. Taping the adipose tissue away helps optimize the exposure to the femoral crease in

patients with morbid obesity.

Goal

The goal is to place the needle tip immediately adjacent to the lateral aspect of the femoral nerve,

either below the fascia iliaca or between the two layers of the fascia iliaca, into the wedge-shaped

tissue space lateral to the femoral artery. Proper deposition of local anesthetic is confirmed by

observation of the femoral nerve being lifted off of the surface of the iliopsoas muscle or of the

spread of the local anesthetic above in the wedged-shaped space lateral to the artery.

Technique

With the patient in the supine position, the skin over the femoral crease is disinfected and the

transducer is positioned to identify the femoral artery and/or nerve (Figure 35-4). If the nerve is not

immediately apparent lateral to the artery, tilting the transducer proximally or distally often helps to

image and highlight the nerve from the rest of the iliopsoas muscle and the more superficial adipose

tissue. In doing so, an effort should be made to identify the iliopsoas muscle and its fascia as well as

the fascia lata because injection underneath a wrong fascial sheath may not result in spread of the

local anesthetic in the desired plane. Once the femoral nerve is identified, a skin wheal of local

anesthetic is made on the lateral aspect of the thigh 1 cm away from the lateral edge of the transducer.

The needle is inserted in-plane in a lateral-to-medial orientation and advanced toward the femoral

nerve (Figure 35-5). If nerve stimulation is used (0.5 mA, 0.1 msec), the passage of the needle

through the fascia iliaca and contact of the needle tip with the femoral nerve usually is associated

with a motor response of the quadriceps muscle group. In addition, a needle passage through the

fascia iliaca is often felt as a “pop” sensation. Once the needle tip is witnessed adjacent (either

above, below, or lateral) to the nerve (Figure 35-6), and after careful aspiration, 1 to 2 mL of local

anesthetic is injected to confirm the proper needle placement (Figure 35-7). When injection of the

local anesthetic does not appear to result in a spread close to the femoral nerve, additional needle

repositions and injections may be necessary.

FIGURE 35-4. To image the femoral nerve and/or femoral vessels, the transducer is positioned

transversely on the femoral crease as shown on the image.

FIGURE 35-5. Transducer position and needle insertion using an in-plane technique to block the

femoral nerve at the femoral crease.

FIGURE 35-6. An ultrasound image of the needle path (1,2) to block the femoral nerve. Both needle

positions are underneath fascia iliaca, one superficial to the femoral nerve (1) and one deeper to it

(2). Either path is acceptable as long as the local anesthetic spreads within the fascia iliaca (white

line) to get in contact with the femoral nerve.

FIGURE 35-7. A simulated needle path (1) and spread of the local anesthetic (blue shaded area) to

block the femoral nerve (FN). FA, femoral artery.

TIPS

The presence of a motor response to nerve stimulation is useful but not necessary to elicit if the nerve,

needle, and local anesthetic spread are well-visualized.

Never inject against high resistance to injection because this may signal an intrafascicular needle

placement.

An out-of-plane technique can also be used. Because the needle tip may not be seen throughout the

procedure, we recommend administering intermittent small boluses (0.5–1 mL) as the needle is

advanced toward the nerve to indicate the location of the needle tip.

Circumferential spread of local anesthetic around the nerve is not necessary for this block. A pool of

local anesthetic immediately adjacent to either the posterolateral or the anterior aspects is sufficient.

In an adult patient, 10 to 20 mL of local anesthetic is adequate for a successful block (Figure 35-

8A and B). The block dynamics and perioperative management are similar to those described in

Chapter 21.

FIGURE 35-8. (A) An actual needle path to block the femoral nerve (FN). (B) Spread of the local

anesthetic (LA) within two layers of the fascia iliaca to encircle the femoral nerve (FN). FA, femoral

artery.

Continuous Ultrasound-Guided Femoral Nerve Block

The goal of the continuous femoral nerve block is similar to that of the non-ultrasound-based

techniques: placement of the catheter in the vicinity of the femoral nerve just deep to the fascia iliaca.

The procedure consists of three phases: needle placement, catheter advancement, and securing the

catheter. For the first two phases of the procedure, ultrasound can be used to ensure accuracy in most

patients. The needle typically is inserted in-plane from the lateral-to-medial direction and underneath

the nerve. Some clinicians prefer inserting the catheter in the longitudinal plane (inferior-to-superior),

analogous to the nerve stimulation-guided technique. No data exist on whether or not one technique is

superior to the other. However, the in-line approach from the lateral-to-medial has worked very well

in our practice, and it is our preference because it is simpler when using ultrasound guidance.

TIP

Both stimulating and nonstimulating catheters can be used, although for simplicity we prefer

nonstimulating catheters for this indication.

The needle is advanced until the tip is adjacent to the nerve. Proper placement of the needle can be

confirmed by obtaining a motor response of the quadriceps/patella, at which point 5 mL of local

anesthetic is injected. This small dose of local anesthetic serves to ensure adequate distribution of the

local anesthetic, as well as to make the advancement of the catheter easier. This first phase of the

procedure does not significantly differ from the single-injection technique. The second phase of the

procedure involves maintaining the needle in the proper position and inserting the catheter 2 to 4 cm

into the space surrounding the femoral nerve (Figure 35-9). Insertion of the catheter can be

accomplished by either a single operator or with a helper. Catheter position is observed on

ultrasound as the catheter is being inserted and/or with an injection through the catheter to document

its proper location.

FIGURE 35-9. Continuous femoral nerve block. Needle is seen inserted in-plane approaching the

nerve from lateral to medial, although it would seem intuitive that a longitudinal insertion of the

needle would have advantages with regard to the catheter placement. The technique demonstrated

here is simpler and routinely used in our practice with consistent success. The catheter should be

inserted 2–4 cm past the needle tip.

The catheter is secured by either taping it to the skin or tunneling. Preference of one technique over

the other varies among clinicians, although no data exist on which one is a more secure method. The

decision regarding which method to use could be based on the patient’s age (no tunneling for younger

patients: less mobile skin, avoidance of posttunneling scar formation), duration of the catheter

therapy, and anatomy. In general, the inguinal area is quite mobile and the femoral nerve is not

particularly deep, two factors that predispose to catheter dislodgment. The more lateral the starting

point for needle insertion for the continuous femoral nerve block, the longer the catheter will be

within the iliacus muscle, which may help prevent dislodgment because muscle tends to stabilize a

catheter better than adipose tissue. Our empirical infusion regimen for femoral nerve block in an adult

patient is ropivacaine 0.2% at a 5 mL/hour infusion rate and a 5 mL/hour patient-controlled bolus.

SUGGESTED READING

Bech B, et al. The successful use of peripheral nerve blocks for femoral amputation. Acta Anaesthesiol

Scand. 2009;53(2):257-260.

Bodner G, et al. Ultrasound of the lateral femoral cutaneous nerve: normal findings in a cadaver and in

volunteers. Reg Anesth Pain Med. 2009;34(3):265-268.

Casati A, et al. Effects of ultrasound guidance on the minimum effective anaesthetic volume required to

block the femoral nerve. Br J Anaesth. 2007;98(6):823-827.

Errando CL. Ultrasound-guided femoral nerve block: catheter insertion in a girl with skeletal

abnormalities [in Spanish]. Rev Esp Anestesiol Reanim. 2009;56(3):197-198.

orget P. Bad needles can’t do good blocks. Reg Anesth Pain Med. 2009;34(6):603.

redrickson M. “Oblique” needle-probe alignment to facilitate ultrasound-guided femoral catheter

placement. Reg Anesth Pain Med. 2008;33(4):383-384.

redrickson MJ, Danesh-Clough TK. Ambulatory continuous femoral analgesia for major knee surgery:

a randomised study of ultrasound-guided femoral catheter placement. Anaesth Intensive Care.

2009;37(5):758-766.

redrickson MJ, Kilfoyle DH, Neurological complication analysis of 1000 ultrasound guided

peripheral nerve blocks for elective orthopaedic surgery: a prospective study. Anaesthesia.

2009;64(8):836-844.

Gurnaney H, Kraemer F, Ganesh A. Ultrasound and nerve stimulation to identify an abnormal location

of the femoral nerve. Reg Anesth Pain Med. 2009;34(6):615.

Helayel PE, et al. Ultrasound-guided sciatic-femoral block for revision of the amputation stump. Case

report. Rev Bras Anestesiol 2008;58(5):482-4, 480-2.

Hotta K, et al. Ultrasound-guided combined femoral nerve and lateral femoral cutaneous nerve blocks

for femur neck fracture surgery—case report [in Japanese]. Masui. 2008;57(7):892-894.

o H, et al. Ultrasound-guided femoral nerve block [in Japanese]. Masui. 2008;57(5):575-579.

Koscielniak-Nielsen ZJ, Rasmussen H, Hesselbjerg L. Long-axis ultrasound imaging of the nerves and

advancement of perineural catheters under direct vision: a preliminary report of four cases. Reg

Anesth Pain Med. 2008;33(5):477-482.

Lang SA. Ultrasound and the femoral three-in-one nerve block: weak methodology and inappropriate

conclusions. Anesth Analg. 1998;86(5):1147-1148.

Marhofer P, et al. Fifteen years of ultrasound guidance in regional anaesthesia: Part 2-recent

developments in block techniques. Br J Anaesth. 2010;104(6):673-683.

Marhofer P, et al. Ultrasonographic guidance improves sensory block and onset time of three-in-one

blocks. Anesth Analg. 1997;85(4):854-857.

Mariano ER, et al. Ultrasound guidance versus electrical stimulation for femoral perineural catheter

insertion. J Ultrasound Med. 2009;28(11):1453-1460.

Murray JM, Derbyshire S, Shields MO. Lower limb blocks. Anaesthesia. 2010;65(Suppl 1):57-66.

Niazi AU, et al. Methods to ease placement of stimulating catheters during in-plane ultrasound-guided

femoral nerve block. Reg Anesth Pain Med. 2009;34(4):380-381.

Oberndorfer U, et al. Ultrasonographic guidance for sciatic and femoral nerve blocks in children. Br J

Anaesth. 2007;98(6):797-801.

O’Donnell BD, Mannion S. Ultrasound-guided femoral nerve block, the safest way to proceed? Reg

Anesth Pain Med. 2006;31(4):387-388.

Reid N, et al. Use of ultrasound to facilitate accurate femoral nerve block in the emergency department.

Emerg Med Australas. 2009;21(2):124-130.

Salinas FV. Ultrasound and review of evidence for lower extremity peripheral nerve blocks. Reg

Anesth Pain Med. 2010;35(2 Suppl):S16-25.

Schafhalter-Zoppoth I, Moriggl B. Aspects of femoral nerve block. Reg Anesth Pain Med.

2006;31(1):92-93.

Sites BD, et al. A single injection ultrasound-assisted femoral nerve block provides side effect-sparing

analgesia when compared with intrathecal morphine in patients undergoing total knee arthroplasty.

Anesth Analg. 2004;99(5):1539-1543.

Sites BD, et al. A comparison of sensory and motor loss after a femoral nerve block conducted with

ultrasound versus ultrasound and nerve stimulation. Reg Anesth Pain Med. 2009;34(5):508-513.

Soong J, Schafhalter-Zoppoth I, Gray AT. The importance of transducer angle to ultrasound visibility of

the femoral nerve. Reg Anesth Pain Med. 2005;30(5):505.

Tran de QH, et al. Ultrasonography and stimulating perineural catheters for nerve blocks: a review of

the evidence. Can J Anaesth. 2008;55(7):447-457.

Tsui B, Suresh S. Ultrasound imaging for regional anesthesia in infants, children, and adolescents: a

review of current literature and its application in the practice of extremity and trunk blocks.

Anesthesiology. 2010;112(2):473-492.

Villegas Duque A, et al. Continuous femoral block for postoperative analgesia in a patient with

poliomyelitis [in Spanish]. Rev Esp Anestesiol Reanim. 2010;57(2):123-124.

Wang AZ, et al. Ultrasound-guided continuous femoral nerve block for analgesia after total knee

arthroplasty: catheter perpendicular to the nerve versus catheter parallel to the nerve. Reg Anesth

Pain Med. 2010;35(2):127-131.

36 Ultrasound-Guided Fascia Iliaca Block

FIGURE 36-1. Needle insertion for the fascia iliaca block. The blue dot indicates the position of the

femoral artery.

General Considerations

Fascia iliaca block is a low-tech alternative to a femoral nerve or a lumbar plexus block. The

mechanism behind this block is that the femoral and lateral femoral cutaneous nerves lie under the

iliacus fascia. Therefore, a sufficient volume of local anesthetic deposited beneath the fascia iliaca,

even if placed some distance from the nerves, has the potential to spread underneath the fascia and

reach these nerves. Traditionally, it was believed that the local anesthetic could also spread

underneath fascia iliaca proximally toward the lumbosacral plexus; however, this has not been

demonstrated consistently. The non-ultrasound technique involved placement of the needle at the

lateral third of the distance from the anterior superior iliac spine and the pubic tubercle, using a

“double-pop” technique as the needle passes through fascia lata and fascia iliaca. However, block

success with this “feel” technique is sporadic because false “pops” can occur. The ultrasound-guided

technique is essentially the same; however, monitoring of the needle placement and local anesthetic

delivery assures deposition of the local anesthetic into the correct plane.

Ultrasound Anatomy

The fascia iliaca is located anterior to the iliacus muscle (on its surface) within the pelvis. It is bound

superolaterally by the iliac crest and medially merges with the fascia overlying the psoas muscle.

Both the femoral nerve and the lateral cutaneous nerve of the thigh lie under the iliacus fascia in their

intrapelvic course. Anatomic orientation begins in the same manner as with the femoral block: with

identification of the femoral artery at the level of the inguinal crease. If it is not immediately visible,

sliding the transducer medially and laterally will eventually bring the vessel into view. Immediately

lateral and deep to the femoral artery and vein is a large hypoechoic structure, the iliopsoas muscle

(Figure 36-2). It is covered by a thin layer of connective tissue fascia, which can be seen separating

the muscle from the subcutaneous tissue superficial to it. The hyperechoic femoral nerve should be

seen wedged between the iliopsoas muscle and the fascia iliaca, lateral to the femoral artery. The

fascia lata (superficial in the subcutaneous layer) is more superficial and may have more then one

layer. Moving the transducer laterally several centimeters brings into view the sartorius muscle

covered by its own fascia as well as the fascia iliaca. Further lateral movement of the transducer

reveals the anterior superior iliac spine (Figure 36-2). Additional anatomical detail can be seen in

cross sectional anatomy in Section 7. Since the anatomy is essentially identical, it is not repeated

here.

FIGURE 36-2. A panoramic view of ultrasound anatomy of the femoral (inguinal) crease area. From

lateral to medial shown are tensor fascia lata muscle (TFLM), sartorius muscle (SaM), Iliac muscle,

fascia iliaca, femoral nerve (FN), and femoral artery (FA). The lateral, middle and medial 1/3s are

derived by dividing the line between the FA and anterior-superior iliac spine in three equal 1/3

sections.

TIP

The transducer should be placed at the level of the femoral crease and oriented parallel to the crease.

Distribution of Blockade

The distribution of anesthesia and analgesia that is accomplished with the fascia iliaca block depends

on the extent of the local anesthetic spread and the nerves blocked. Blockade of the femoral nerve

results in anesthesia of the anterior and medial thigh (down to and including the knee) and anesthesia

of a variable strip of skin on the medial leg and foot. The femoral nerve also contributes to articular

fibers to both the hip and knee. The lateral femoral cutaneous nerve confers cutaneous innervation to

the anterolateral thigh. For a more comprehensive review of the femoral and lateral femoral

cutaneous nerves and lumbar plexus nerve distribution, refer to Chapter 01, Essential Regional

Anesthesia Anatomy.

Equipment

Equipment needed is:

Ultrasound machine with linear transducer (6–14 MHz), sterile sleeve, and gel

Standard nerve block tray (described in the equipment section)

Two 20-mL syringes containing local anesthetic

80- to 100-mm, 22-gauge needle (short bevel aids in feeling the fascial “pops”)

Sterile gloves

Landmarks and Patient Positioning

This block is typically performed with the patient in the supine position, with the bed or table

flattened to maximize access to the inguinal area (Figure 36-3). Although palpation of a femoral pulse

is a useful landmark, it is not required because the artery is quickly visualized by placement of the

transducer transversely on the inguinal crease, followed by slow movement laterally or medially.

FIGURE 36-3. The ruler is positioned to divide the distance between the femoral artery and anterior

superior spine in 3 equal parts as described in Figure 36-2.

Goal

The goal is to place the needle tip under the fascia iliaca approximately at a lateral third of the line

connecting anterior superior iliac spine to the pubic tubercle (injection is made several centimeters

lateral to the femoral artery) and to deposit a relatively large volume (30–40 mL) of local

anesthetic until its spread laterally toward the iliac spine and medially toward the femoral nerve is

documented with ultrasound visualization.

Technique

With the patient in the proper position, the skin is disinfected and the transducer positioned to identify

the femoral artery and the iliopsoas muscle and fascia iliaca. The transducer is moved laterally until

the sartorius muscle is identified. After a skin wheal is made, the needle is inserted in-plane (Figure

36-1). As the needle passes through fascia iliaca the fascia is first seen indented by the needle. As the

needle eventually pierces through the fascia, pop may be felt and the fascia may be seen to “snap”

back on the ultrasound image. After negative aspiration, 1 to 2 mL of local anesthetic is injected to

confirm the proper injection plane between the fascia (Figure 36-4) and the iliopsoas muscle (Figure

36-5A, B, and C). If local anesthetic spread occurs above the fascia or within the substance of the

muscle itself, additional needle repositions and injections may be necessary. A proper injection will

result in the separation of the fascia iliaca by the local anesthetic in the medial-lateral direction from

the point of injection as described. If the spread is deemed inadequate, additional injections laterally

or medially to the original needle insertion or injection can be made to facilitate the medial-lateral

spread.

FIGURE 36-4. Magnified image of the fascia iliaca.

FIGURE 36-5. (A) Path of the needle for the fascia iliaca block. The needle is shown underneath

the fascia iliaca lateral to the femoral artery (not seen) but not too deep to be lodged into the iliac

muscle. (B) A simulated spread (area shaded in blue) of the local anesthetic to accomplish a fascia

iliaca block. (C) Spread of the local anesthetic (LA) under the fascia iliaca. Some local anesthetic is

also seen deep within the iliacus muscle (yellow arrows). When this occurs, the needle should be

pulled back more superficially. (D) Extension of the LA laterally underneath the sartorius muscle.

Some LA fills the adipose tissue between fascia iliaca and iliacus muscle (yellow arrows).

TIPS

The fascia iliaca block is a large-volume block. Its success depends on the spread of local anesthetic

along a connective tissue plane. For this reason, 30 to 40 mL of injectate is necessary to accomplish

the block.

The spread of the local anesthetic is monitored with ultrasonography. If the pattern of the spread is not

adequate (e.g., the local is forming a collection in one location and not “layering out”), injection is

stopped and needle repositioned before continuing. Additional injections may be made to assure

adequate spread.

In an adult patient, between 30 and 40 mL of local anesthetic is usually required for successful

blockade. The success of the block is best predicted by documenting the spread of the local anesthetic

toward the femoral nerve medially and underneath the sartorius muscle laterally. In obese patients, an

out of plane technique may be favored. The block should result in blockade of the femoral in all

instances (100%) and lateral femoral nerve (80%-100%). Block of anterior branch of the obturator

nerve is unreliable with fascia iliaca block. When required, this nerve should be blocked as

described in Chapter 37.

SUGGESTED READING

Dolan J, Williams A, Murney E, Smith M, Kenny GN. Ultrasound guided fascia iliaca block: a

comparison with the loss of resistance technique. Reg Anesth Pain Med. 2008;33:526-531.

Foss NB, Kristensen BB, Bundgaard M, et al. Fascia iliaca compartment blockade for acute pain

control in hip fracture patients: a randomized, placebo-controlled study. Anesthesiology.

2007;106:773-778.

Hebbard P, Ivanusic J, Sha S. Ultrasound-guided supra-inguinal fascia iliaca block: a cadaveric

evaluation of a novel approach. Anaesthesia. 2011;66:300-305.

Minville V, Gozlan C, Asehnoune K, et al. Fascia-iliaca compartment block for femoral bone fracture

in prehospital medicine in a 6-yr-old child. Eur J Anaesthesiol. 2006;23:715-716.

Mouzopolous G, Vasiliadis G, Lasanianos N, et al. Fascia iliaca block prophylaxis for hip fracture

patients at risk for delirium: a randomized placebo-controlled study. J Orthop Traumatol.

2009;10:127-133.

Swenson JD, Bay N, Loose E, et al. Outpatient management of continuous peripheral nerve catheters

placed using ultrasound guidance: an experience in 620 patients. Anesth Analg. 2006;103:1436-1443.

Wambold D, Carter C, Rosenberg AD. The fascia iliaca block for postoperative pain relief after knee

surgery. Pain Pract. 2001;1:274-277.

Yun MJ, Kim YH, Han MK, et al. Analgesia before a spinal block for femoral neck fracture: fascia

iliaca compartment block. Acta Anaesthesiol Scand. 2009;53:1282-1287.

Ultrasound-Guided Obturator Nerve Block

FIGURE 37-1. Needle insertion using an in-plane technique to accomplish an obturator nerve block.

General Considerations

There is renewed interest in obturator nerve block because of the recognition that the obturator nerve

is spared after a “3-in-1 block” and yet can be easier accomplished using ultrasound guidance. In

some patients, the quality of postoperative analgesia is improved after knee surgery when an obturator

nerve block is added to a femoral nerve block. However, a routine use of the obturator block does not

result in improved analgesia in all patients having knee surgery. For this reason, obturator block is

used selectively.

Ultrasound-guided obturator nerve block is simpler to perform, more reliable, and associated with

patient discomfort when compared with surface landmark-based techniques.

There are two approaches to performing ultrasound-guided obturator nerve block. The interfascial

injection technique relies on injecting local anesthetic solution into the fascial planes that contain the

branches of the obturator nerve. With this technique, it is not important to identify the branches of

obturator nerve on the sonogram but rather to identify the adductor muscles and the fascial boundaries

within which the nerves lie. This is similar in concept to other fascial plane blocks (e.g. transversus

abdominis plane block [TAP]) where local anesthetic solution is injected between the internal

oblique and transverse abdominis muscles without the need to indentify the nerves. Alternatively, the

branches of the obturator nerve can be visualized with ultrasound imaging and blocked after eliciting

a motor response.

Anatomy

The obturator nerve forms in the lumbar plexus from the anterior primary rami of L2-L4 roots and

descends to the pelvis in the psoas muscle. In most individuals, the nerve divides into an anterior

branch and posterior branch before exiting the pelvis through the obturator foramen. In the thigh, at the

level of the femoral crease, the anterior branch is located between the fascia of pectineus and

adductor brevis muscles. The anterior branch lies further caudad between the pectineus and adductor

brevis muscles. The anterior branch provides motor fibers to the adductor muscles and cutaneous

branches to the medial aspect of the thigh. The anterior branch has a great variability in the extent of

sensory innervation of the medial thigh. The posterior branch lies between the fascial planes of the

adductor brevis and adductor magnus muscles (Figures 37-2 and 37-3). The posterior branch is

primarily a motor nerve for the adductors of the thigh; however it also may provide articular branches

to the medial aspect of the knee joint. The articular branches to the hip joint usually arise from the

obturator nerve proximal to its division and only occasionally from the individual branches (Figure

37-4).

FIGURE 37-2. Cross-sectional anatomy of relevance to the obturator nerve block. Shown are

femoral vessels (FV, FA), pectineus muscle, adductor longus (ALM), adductor brevis (ABM), and

adductor magnus (AMM) muscles. The anterior branch of the obturator nerve is seen between ALM

and ABM, whereas the posterior branch is seen between ABM and AMM.

FIGURE 37-3. Anterior branch (Ant. Br.) of the obturator nerve (ObN) is seen between the adductor

longus (ALM) and the adductor brevis (ABM), whereas the posterior branch (Post. Br.) is seen

between the ABM and the adductor magnus (AMM).

FIGURE 37-4. The course and divisions of the obturator nerve and their relationship to the adductor

muscles.

TIP

A psoas compartment (lumbar plexus) block is required to reliably block the articular branches of the

obturator nerve to the hip joint because they usually depart proximal to where obturator nerve block

is performed.

Distribution of Blockade

Because there is great variability in the cutaneous innervation to the medial thigh, demonstrated

weakness or absence of adductor muscle strength is the best method of documenting a successful

obturator nerve block, rather than a decreased skin sensation in the expected territory. However, the

adductor muscles of the thigh may have co-innervation from the femoral nerve (pectineus) and sciatic

nerve (adductor magnus). For this reason, complete loss of adductor muscle strength is also

uncommon despite a successful obturator nerve block.

TIP

A simple method of assessing adductor muscle strength (motor block) is to instruct the patient to

adduct the blocked leg from an abducted position against resistance. Weakness or inability to adduct

the leg indicates a successful obturator nerve block.

Equipment

Equipment needed includes the following:

Ultrasound machine with linear (or curved) transducer (5–13 MHz), sterile sleeve, and gel

Standard block tray

A 20-mL syringe containing local anesthetic solution

A 10-cm, 21–22 gauge short-bevel insulated needle

Peripheral nerve stimulator (optional)

Sterile gloves

Landmarks and Patient Positioning

With the patient supine, the thigh is slightly abducted and laterally rotated. The block can be

performed either at the level of femoral (inguinal) crease medial to the femoral vein or 1 to 3 cm

inferior to the inguinal crease on the medial aspect (adductor compartment) of the thigh (Figure 37-5).

FIGURE 37-5. A transducer position to image the obturator nerve. The transducer is positioned

medial to the femoral artery slightly below the femoral crease.

GOAL

The goal of the interfascial injection technique for blocking the obturator nerve is to inject local

anesthetic solution into the interfascial space between the pectineus and adductor brevis muscles

to block the anterior branch and the adductor brevis and adductor magnus muscles to block the

posterior branch. When using ultrasound guidance with nerve stimulation, the anterior and

posterior branches of the of obturator nerve are identified and stimulated to elicit a motor

response prior to injecting local anesthetic solution around each branch.

Technique

The interfascial approach is performed at the level of the femoral crease. With this technique, it is

important to identify the adductor muscles and their fascial planes in which the individual nerves are

enveloped.

With the patient supine, the leg is slightly abducted and externally rotated. The ultrasound

transducer is placed to visualize the femoral vessels. The transducer is advanced medially along the

crease to identify the adductor muscles and their fasciae. The anterior branch is sandwiched between

the pectineus and adductor brevis muscles, whereas the posterior branch is located the fascial plane

between the adductor brevis and adductor magnus muscles. The block needle is advanced to initially

position the needle tip between the pectineus and adductor brevis at the junction of middle and

posterior third of their fascial interface (Figure 37-6). At this point, 5 to 10 mL of local anesthetic

solution is injected. The needle is advanced further to position the needle tip between the adductor

brevis and adductor magnus muscles, and 5 to 10 mL of local anesthetic is injected (Figure 37-6B). It

is important for the local anesthetic solution to spread into the interfascial space and not be injected

into the muscles. Correct injection of local anesthetic solution into the interfascial space results in

accumulation of the injectate between target muscles. The needle may have to be repositioned to

allow for precise interfascial injection.

FIGURE 37-6. (A) Needle paths required to reach the anterior branch and the posterior branch

of the obturator nerve (ObN). (B) Simulated dispersion of the local anesthetic to block the anterior

and posterior branches of the obturator nerve. In both examples, an in-plane needle insertion is

used.

Alternatively, the cross-sectional image of branches of the obturator nerve can be obtained by

scanning 1 to 3 cm distal to the inguinal crease on the medial aspect of thigh. The nerves appear as

hyperechoic, flat, lip-shaped structures invested in the fascia of adductor muscles. The anterior

branch is located between the adductor longus and adductor brevis muscles, whereas the posterior

branch is between the adductor brevis and adductor magnus muscles. An insulated block needle

attached to the nerve stimulator is advanced toward the nerve either in an out-of-plane or in-plane

trajectory. After eliciting the contraction of the adductor muscles, 5 to 7 mL of local anesthetic is

injected around each branch of the obturator nerve (Figure 37-6B).

TIPS

The usual precautions to prevent intravascular injection should be taken because this is a highly

vascular area (standard monitoring, adding epinephrine to local anesthetic solution, fractionating the

dose, maintaining verbal contact with patient).

When nerve stimulation is used, adduction of the thigh can be obtained without proper nerve

identification. This is due to direct muscle or muscle branch stimulation with currents >1.0 mA.

Decreasing the current intensity helps distinguish between nerve versus direct muscle stimulation.

It is not necessary to optimize motor response to a predetermined nerve stimulator current; the role of

nerve stimulation is simply to confirm that a structure is indeed a nerve.

SUGGESTED READING

Akkaya T, Ozturk E, Comert A, et al. Ultrasound-guided obturator nerve block: a sonoanatomic study of

a new methodologic approach. Anesth Analg. 2009;108(3):1037-1041.

Anagnostopoulou S, Kostopanagiotou G, Paraskeuopoulos T, Chantzi C, Lolis E, Saranteas T. Anatomicvariations of the obturator nerve in the inguinal region: implications in conventional and ultrasound

regional anesthesia techniques. Reg Anesth Pain Med. 2009;34:33-39.

Bouaziz H, Vial F, Jochum D, et al. An evaluation of the cutaneous distribution after obturator nerve

block. Anesth Analg. 2002;94:445-449.

Macalou D, Trueck S, Meuret P, et al. Postoperative analgesia after total knee replacement: the effect ofan obturator nerve block added to the femoral 3-in-1 nerve block. Anesth Analg. 2004;99:251-254.

Marhofer P, Harrop-Griffiths W, Willschke H, Kirchmair L: Fifteen years of ultrasound guidance in

regional anaesthesia: Part 2-recent developments in block techniques. Br J Anaesth 2010; 104:673-

83.

McNamee DA, Parks L, Milligan KR. Post-operative analgesia following total knee replacement: an

evaluation of the addition of an obturator nerve block to combined femoral and sciatic nerve block.

Acta Anaesthesiol Scand. 2002;46:95-99.

Sakura S, Hara K, Ota J, Tadenuma S: Ultrasound-guided peripheral nerve blocks for anterior cruciate

ligament reconstruction: effect of obturator nerve block during and after surgery. J Anesth

2010;24:411-7.

Sinha SK, Abrams JH, Houle T, Weller R. Ultrasound guided obturator nerve block: an interfascial

injection approach without nerve stimulation. Reg Anesth Pain Med. 2009;34(3):261-264.

Snaith R, Dolan J: Ultrasound-guided interfascial injection for peripheral obturator nerve block in the

thigh. Reg Anesth Pain Med 2010;35:314-5.

Soong J, Schafhalter-Zoppoth I, Gray AT. Sonographic imaging of the obturator nerve for regional

block. Reg Anesth Pain Med. 2007;32:146-151.

Ultrasound-Guided Saphenous Nerve Block

FIGURE 38-1. Needle insertion to block the saphenous nerve at the level of the mid thigh (A) or

below the knee (B).

General Considerations

The saphenous nerve is the terminal sensory branch of the femoral nerve. It supplies innervation to the

medial aspect of the leg down to the ankle and foot. Blockade of the nerve can be sufficient for

superficial procedures in this area; however, it is most useful as a supplement to a sciatic block for

foot and ankle procedures that involve the superficial structures in medial territory. The use of

ultrasound guidance has improved the success rates of the saphenous blocks, compared with field

blocks below the knee and blind transsartorial approaches. The ultrasound-guided techniques

described here are relatively simple, quick to perform, and fairly reproducible.

Ultrasound Anatomy

The sartorius muscle forms a “roof” over the adductor canal in the lower half of the thigh in its

descent laterally-to-medially across the anterior thigh. The muscle appears as an oval shape beneath

the subcutaneous layer of adipose tissue. Often, the femoral artery, which passes beneath the muscle,

can also be palpated. The sides of the triangular canal are formed by the vastus medialis laterally and

adductor longus or magnus medially (depending on how proximal or distal the scan is). The

saphenous nerve is infrequently seen on the ultrasound image; however, sometimes it is visualized as

a small round hyperechoic structure medial to the artery. A femoral vein accompanies the artery and

saphenous nerve, which are all typically visualized at 2 to 3 cm depth. When attempting to identify the

saphenous nerve on ultrasound image, the following anatomic considerations should be kept in mind:

Above the knee: The saphenous nerve pierces the fascia lata between the tendons of the sartorius and

gracilis muscles before becoming a subcutaneous nerve.

The saphenous nerve also may surface between the sartorius and vastus medialis muscles. (Figure 38-

2 A, B, and C).

FIGURE 38-2. (A) Transducer and needle position for a saphenous nerve block at the level of the

midthigh. (B) Ultrasound anatomy demonstrating saphenous nerve (SaN) in the tissue plane between

the sartorius muscle (SM) and vastus medialis muscle. (C) Cross-sectional anatomy of the saphenous

nerve at the level of the thigh. Saphenous nerve is shown positioned between the SM and the vastus

medialis muscle. In this example the sartorius nerve is positioned superficially to the femoral artery

(FA) and vein (unlabeled oval structure posterior to the FA).

Below the knee, the nerve passes along the tibial side of the leg, adjacent to the great saphenous vein

subcutaneously (Figure 38-3A, B, and C).

FIGURE 38-3. (A) Ultrasound transducer and needle insertion technique to block the saphenous

nerve (SaN) at the level of the tibial tuberosity. (B) Cross-sectional anatomy of the SaN at the level

of the tibial tuberosity. (C) Ultrasound image of the saphenous nerve (SaN) at the level below the

knee. SaN is seen in the immediate vicinity of the saphenous vein (SV). Transducer should be applied

lightly to avoid compression of the saphenous vein (SV) because the vein serves as an important

landmark for technique.

At the ankle, a branch of the nerve is located medially next to the subcutaneously positioned saphenous

vein.

Distribution of Blockade

Saphenous nerve block results in anesthesia of a variable strip of skin on the medial leg and foot. For

a more comprehensive review of the femoral and saphenous nerve distributions, see Chapter 1. Of

note, although saphenous nerve is a strictly sensory block, an injection of the local anesthetic in the

adductor canal can result in the partial motor block of the vastus medialis. For this reason, caution

must be excercised when advising patients regarding the safety of unsupported ambulation after

proximal saphenous block.

Equipment

Equipment needed is as follows:

Ultrasound machine with linear transducer (8–14 MHz), sterile sleeve, and gel

Standard nerve block tray (described in Chapter 3)

One 10-mL syringe containing local anesthetic

A 50-mm, 22-gauge short-bevel needle

Peripheral nerve stimulator to elicit sensory sensation.

Sterile gloves

Landmarks and Patient Positioning for Proximal Approach

The patient is placed in any position that allows for comfortable placement of the ultrasound

transducer and needle advancement. Although prone and lateral approaches are possible, this block

typically is performed with the patient in the supine position, with the thigh abducted and externally

rotated to allow access to the medial thigh (Figure 38-2A). If difficulty confirming the sartorius

muscle is encountered, exposure of the entire thigh in order to scan down from the anterosuperior

iliac spine is useful.

GOAL

The goal is to place the needle tip just medial to the femoral artery, below the sartorius muscle,

and to deposit 5 to 10 mL of local anesthetic until its spread around the artery is confirmed with

ultrasound visualization. Block of the nerve at other, more distal and superficial locations

consists of a simple subcutaneous infiltration of the tissues in the immediate vicinity of the nerve

but can be done under ultrasound guidance.

Technique

With the patient in the proper position, the skin is disinfected and the transducer is placed

anteromedially, approximately mid thigh position or somewhat lower. If the artery is not immediately

obvious, several maneuvers to identify it can be used, including color Doppler scanning to trace the

femoral artery caudally from the inguinal crease. Once the femoral artery is identified, the needle is

inserted in-plane in a lateral-to-medial orientation, and advanced toward the femoral artery (Figure

38-4A). If nerve stimulation is used (0.5 mA, 0.1 msec), the passage of the needle through the

sartorius and/or adductor muscles and into the adductor canal is usually associated with the patient

reporting a paresthesia in the saphenous nerve distribution. Once the needle tip is visualized medial

to the artery and after careful aspiration, 1 to 2 mL of local anesthetic is injected to confirm the

proper injection site (Figure 38-4B). When injection of the local anesthetic does not appear to result

in its spread beside the femoral artery, additional needle repositions and injections may be necessary.

FIGURE 38-4. (A) Simulated needle path to reach the saphenous nerve (SaN) at the level of the

midthigh. (B) Simulated needle path and the distribution of the local anesthetic (area shaded in

blue) to anesthetize the SaN at the midthigh level. SM, sartorius muscle; Vastus M, vastus medialus

muscle. Femoral artery is not well seen in this image; it is positioned immediately posterior to SaN.

TIPS

An out-of-plane technique can also be used through the belly of the sartorius muscle. Because the

needle tip may not be seen throughout the procedure, small boluses of local anesthetic are

administered (0.5–1 mL) as the needle is advanced toward the adductor canal, to confirm the location

of the needle tip.

Visualization of the nerve is not necessary for this block; the saphenous nerve is not always well

imaged. Administration of 5 to 10 mL of local anesthetic next to the artery should suffice without

confirming the nerve position.

In an adult patient, usually 5 to 10 mL of local anesthetic is adequate for successful blockade.

Because the saphenous nerve is a purely sensory nerve, high concentrations of local anesthetic are not

required and in fact may delay patient ambulation should local anesthetic spread to one of the motor

branches of the femoral nerve serving the quadriceps muscle.

TIP

The nerve to the vastus medialis muscle also lies in the adductor canal (in its proximal portion).

Practitioners should be aware of this and the potential for partial quadriceps weakness following this

approach to the saphenous nerve block. Patient education and assistance with ambulation should be

encouraged.

SUGGESTED READING

Davis JJ, Bond TS, Swenson JD. Adductor canal block: more than just the saphenous nerve? Reg

Anesth Pain Med. 2009;34:618-619.

Gray AT, Collins AB. Ultrasound-guided saphenous nerve block. Reg Anesth Pain Med. 2003;28:148.

Horn JL, Pitsch T, Salinas F, Benninger B. Anatomic basis to the ultrasound-guided approach for

saphenous nerve blockade. Reg Anesth Pain Med. 2009;34:486-489.

Kirkpatrick JD, Sites BD, Antonakakis JG. Preliminary experience with a new approach to performing

an ultrasound-guided saphenous nerve block in the mid- to proximal femur. Reg Anesth Pain Med.

2010;35:222-223.

Krombach J, Gray AT. Sonography for saphenous nerve block near the adductor canal. Reg Anesth PainMed. 2007;32:369-370.

Lundblad M, Kapral S, Marhofer P, et al. Ultrasound-guided infrapatellar nerve block in human

volunteers: description of a novel technique. Br J Anaesth. 2006;97:710-714.

Manickam B, Perlas A, Duggan E, Brull R, Chan VW, Ramlogan R. Feasibility and efficacy of

ultrasound-guided block of the saphenous nerve in the adductor canal. Reg Anesth Pain Med.

2009;34:578-580.

Miller BR. Ultrasound-guided proximal tibial paravenous saphenous nerve block in pediatric patients.

Paediatr Anaesth. 2010;20:1059-1060

Saranteas T, Anagnostis G, Paraskeuopoulos T, Koulalis D, Kokkalis Z, Nakou M, Anagnostopoulou S,

Kostopanagiotou G. Anatomy and clinical implications of the ultrasound-guided subsartorial

saphenous nerve block. Reg Anesth Pain Med. 2011;36:399-402.

Tsai PB, Karnwal A, Kakazu C, Tokhner V, Julka IS. Efficacy of an ultrasound-guided subsartorial

approach to saphenous nerve block: a case series. Can J Anaesth. 2010;57:683-688.

Tsui BC, Ozelsel T. Ultrasound-guided transsartorial perifemoral artery approach for saphenous nerve

block. Reg Anesth Pain Med. 2009;34:177-178.

Ultrasound-Guided Sciatic Block

FIGURE 39.1-1. (A) Needle insertion to block the sciatic nerve using an anterior approach. Note that

a curved (phased array) lower frequency transducer is used either in-plane (shown) or out-of-plane

needle insertion can be used. (B) Transgluteal approach to sciatic block; patient position, transducer

(curved) placement and needle insertion.

PART 1: ANTERIOR APPROACH

General Considerations

The anterior approach to sciatic block can be useful in patients who cannot be positioned in the

lateral position due to pain, trauma, presence of external fixation devices interfering with positioning,

and other issues. It also may be well-suited to patients who require postoperative blocks for

analgesia following a total knee arthroplasty. Ultrasonography adds the benefit of no requirement for

the palpation of a femoral pulse or the use of geometry for identification of the skin puncture point. In

addition, using the ultrasound-guided approach should reduce the risk of puncture of the femoral

artery as compared with the landmark-based approach. The actual scanning and needle insertion are

performed on the anteromedial aspect of the proximal thigh, rather than the anterior surface, and may

require a slight abduction and external rotation of the thigh. This block is not well suited to insertion

of catheters because a large needle must traverse several muscles (causing pain and possibly

hematomas), an awkward catheter location (medial thigh), and catheter insertion at approximately

perpendicular angle to the sciatic nerve is difficult.

Ultrasound Anatomy

The sciatic nerve is imaged approximately at the level of the minor trochanter. At this location, a

curved transducer placed over the anteromedial aspect of the thigh will reveal the musculature of all

three fascial compartments of the thigh: anterior, medial, and posterior (Figures 39.1-2 and 39.1-3).

Beneath the superficial sartorius muscle is the femoral artery, and deep and medial to this vessel is

the profunda femoris artery. Both of these can be identified with color Doppler ultrasound for

orientation. The femur is easily seen as a hyperechoic rim with the corresponding shadow beneath the

vastus intermedius. Medial to the femur is the body of the adductor magnus muscle, separated by the

fascial plane(s) of the hamstrings muscles. The sciatic nerve is visualized as a hyperechoic, slightly

flattened oval structure sandwiched between these two muscle planes. The nerve is typically

visualized at a depth of 6 to 8 cm (Figure 39.1-3).

FIGURE 39.1-2. Cross- sectional anatomy of the sciatic nerve (ScN). Shown are femoral artery

(FA), adductor longus muscle (ALM), pectineus muscle, adductor magnus muscle (AMM), adductor

brevis muscle (ABM), gracilis muscle (GsM), and the femur. The sciatic nerve is seen posterior to

the AMM.

FIGURE 39.1-3. Ultrasound anatomy of the sciatic nerve. From superficial to deep; femoral artery

(FA) and femur laterally, adductor magnus muscle (AMM) and sciatic nerve (ScN) laterally. The

sciatic nerve is typically located at a depth of 6 to 8 cm.

Distribution of Blockade

Sciatic nerve block results in anesthesia of the posterior aspect of the knee, hamstrings muscles, and

entire lower limb below the knee, both motor and sensory, with the exception of skin on the medial

leg and foot (saphenous nerve). The skin of the posterior aspect of the thigh is supplied by the

posterior cutaneous nerve of the thigh, which has its origin from the sciatic nerve more proximal than

the anterior approach. It is, therefore, not blocked by the anterior approach. Practically, however, the

lack of anesthesia in its distribution is of little clinical consequence. For a more comprehensive

review of the sciatic nerve distribution, see Chapter 1.

Equipment

Equipment needed is as follows:

Ultrasound machine with curved (phased array) transducer (2–8 MHz), sterile sleeve, and gel

Standard nerve block tray (described in the equipment section)

One 20-mL syringe containing local anesthetic

A 100-mm, 21 to 22 gauge short-bevel insulated stimulating needle

Peripheral nerve stimulator

Sterile gloves

Landmarks and Patient Positioning

Anterior approach to sciatic nerve block is performed with the patient in the supine position. The hip

is abducted to facilitate transducer and needle placement (Figure 39.1-4 and 39.1-5). When feasible,

the hip and knee should be somewhat flexed to facilitate exposure. If nerve stimulation is to be used at

the same time (recommended), exposure of the calf and foot are required to observe motor responses.

In either case, it is useful to expose the entire thigh to appreciate the distance from the groin to knee.

FIGURE 39.1-4. Transducer position to visualize the sciatic nerve through the anterior approach.

FIGURE 39.1-5. A simulated needle path using an out of plane technique to reach the sciatic nerve

(ScN) through the anterior approach.

GOAL

The goal is to place the needle tip immediately adjacent to the sciatic nerve, between the adductor

muscles and biceps femoris muscle, and deposit 15 to 20 mL of local anesthetic until spread

around the nerve is documented.

Technique

With the patient in the proper position, the skin is disinfected and the transducer positioned so as to

identify the sciatic nerve. If the nerve is not immediately apparent, sliding and tilting the transducer

proximally or distally can be useful to improve the contrast and bring the nerve “out” of the

background from the musculature. Finally, if the patient is able to dorsiflex and/or plantar flex the

ankle, this maneuver often causes the nerve to rotate or otherwise move within the muscular planes,

facilitating identification. Once identified, the needle is inserted in-plane or out of plane (more

common in our program) from the medial aspect of the thigh and advanced toward the sciatic nerve

(Figure 39.1-5). If nerve stimulation is used (1.0 mA, 0.1 msec), the contact of the needle tip with the

sciatic nerve is usually associated with a motor response of the calf or foot. Once the needle tip is

deemed to be in the proper position, 1 to 2 mL of local anesthetic is injected to confirm the adequate

distribution of injectate. Such injection helps delineate the sciatic nerve within its intramuscular

tunnel, but it may displace the sciatic nerve away from the needle. Improper spread of the local

anesthetic or nerve displacement may require an additional advancement of the needle. When

injection of the local anesthetic does not appear to result in a spread around the sciatic nerve,

additional needle repositions and injections are necessary.

TIP

Insertion of the needle in an out-of-plane manner with hydro-dissection/localization is often a more

logical method to accomplish this block.

In an adult patient, 15 to 20 mL of local anesthetic is usually adequate for successful blockade

(Figure 39.1-6). Although a single injection of such volume of local anesthetic suffices, it may be

beneficial to inject two to three smaller aliquots at different locations to assure the spread of the local

anesthetic solution around the sciatic nerve. The block dynamics and perioperative management are

similar to those described in the nerve stimulator technique section, Chapter 19.

FIGURE 39.1-6. Simulated needle path using an out-of-plane technique with local anesthetic and

proper distribution of local anesthetic to anesthetize the sciatic nerve (ScN).

SUGGESTED READING

Abbas S, Brull R. Ultrasound-guided sciatic nerve block: description of a new approach at the

subgluteal space. Br J Anaesth. 2007;99:445-446.

Barrington MJ, Lai SL, Briggs CA, Ivanusic JJ, Gledhill SR. Ultrasound-guided midthigh sciatic nerve

block-a clinical and anatomical study. Reg Anesth Pain Med. 2008;33:369-376.

Bruhn J, Moayeri N, Groen GJ, et al. Soft tissue landmark for ultrasound identification of the sciatic

nerve in the infragluteal region: the tendon of the long head of the biceps femoris muscle. Acta

Anaesthesiol Scand. 2009; 53: 921-5

Bruhn J, Van Geffen GJ, Gielen MJ, Scheffer GJ. Visualization of the course of the sciatic nerve in adult

volunteers by ultrasonography. Acta Anaesthesiol Scand. 2008;52:1298-1302.

Chan VW, Nova H, Abbas S, McCartney CJ, Perlas A, Xu DQ. Ultrasound examination and localization

of the sciatic nerve: a volunteer study. Anesthesiology. 2006;104:309-314.

Chantzi C, Saranteas T, Zogogiannis J, Alevizou N, Dimitriou V. Ultrasound examination of the sciatic

nerve at the anterior thigh in obese patients. Acta Anaesthesiol Scand. 2007;51:132.

Danelli G, Ghisi D, Fanelli A, et al. The effects of ultrasound guidance and neurostimulation on the

minimum effective anesthetic volume of mepivacaine 1.5% required to block the sciatic nerve using

the subgluteal approach. Anesth Analg. 2009;109:1674-1678.

Danelli G, Ghisi D, Ortu A. Ultrasound and regional anesthesia technique: are there really ultrasound

guidance technical limits in sciatic nerve blocks? Reg Anesth Pain Med. 2008;33:281-282.

Domingo-Triado V, Selfa S, Martinez F, et al. Ultrasound guidance for lateral midfemoral sciatic nerve

block: a prospective, comparative, randomized study. Anesth Analg. 2007;104:1270-1274.

redrickson MJ, Kilfoyle DH. Neurological complication analysis of 1000 ultrasound guided

peripheral nerve blocks for elective orthopaedic surgery: a prospective study. Anaesthesia.

2009;64:836-844.

Gnaho A, Eyrieux S, Gentili M. Cardiac arrest during an ultrasound-guided sciatic nerve block

combined with nerve stimulation. Reg Anesth Pain Med. 2009;34:278.

Gray AT, Collins AB, Schafhalter-Zoppoth I. Sciatic nerve block in a child: a sonographic approach.

Anesth Analg. 2003;97:1300-1302.

Hamilton PD, Pearce CJ, Pinney SJ, Calder JD. Sciatic nerve blockade: a survey of orthopaedic foot

and ankle specialists in North America and the United Kingdom. Foot Ankle Int. 2009;30:1196-1201.

Karmakar MK, Kwok WH, Ho AM, Tsang K, Chui PT, Gin T. Ultrasound-guided sciatic nerve block:

description of a new approach at the subgluteal space. Br J Anaesth. 2007;98:390-395.

Latzke D, Marhofer P, Zeitlinger M, et al. Minimal local anaesthetic volumes for sciatic nerve block:

evaluation of ED 99 in volunteers. Br J Anaesth. 2010;104:239-244.

Marhofer P, Harrop-Griffiths W, Willschke H, Kirchmair L. Fifteen years of ultrasound guidance in

regional anaesthesia: Part 2-recent developments in block techniques. Br J Anaesth. 2010;104:673-

683.

Murray JM, Derbyshire S, Shields MO. Lower limb blocks. Anaesthesia. 2010;65(Suppl 1):57-66.

Oberndorfer U, Marhofer P, Bosenberg A, et al. Ultrasonographic guidance for sciatic and femoral

nerve blocks in children. Br J Anaesth. 2007;98:797-801.

Ota J, Sakura S, Hara K, Saito Y. Ultrasound-guided anterior approach to sciatic nerve block: a

comparison with the posterior approach. Anesth Analg. 2009;108:660-665.

ham Dang C, Gourand D. Ultrasound imaging of the sciatic nerve in the lateral midfemoral approach.

Reg Anesth Pain Med. 2009;34:281-282.

alinas FV. Ultrasound and review of evidence for lower extremity peripheral nerve blocks. Reg

Anesth Pain Med. 2010;35:S16-25.

aranteas T. Limitations in ultrasound imaging techniques in anesthesia: obesity and muscle atrophy?

Anesth Analg. 2009;109:993-994.

aranteas T, Chantzi C, Paraskeuopoulos T, et al. Imaging in anesthesia: the role of 4 MHz to 7 MHz

sector array ultrasound probe in the identification of the sciatic nerve at different anatomic locations.

Reg Anesth Pain Med. 2007;32:537-538.

aranteas T, Chantzi C, Zogogiannis J, et al. Lateral sciatic nerve examination and localization at the

mid-femoral level: an imaging study with ultrasound. Acta Anaesthesiol Scand. 2007;51:387-388.

aranteas T, Kostopanagiotou G, Paraskeuopoulos T, Vamvasakis E, Chantzi C, Anagnostopoulou S.

Ultrasound examination of the sciatic nerve at two different locations in the lateral thigh: a new

approach of identification validated by anatomic preparation. Acta Anaesthesiol Scand.

2007;51:780-781.

ites BD, Neal JM, Chan V. Ultrasound in regional anesthesia: where should the “focus” be set? Reg

Anesth Pain Med. 2009;34:531-533.

Tran de QH, Munoz L, Russo G, Finlayson RJ. Ultrasonography and stimulating perineural catheters for

nerve blocks: a review of the evidence. Can J Anaesth. 2008;55:447-457.

Tsui BC, Dillane D, Pillay J, Ramji AK, Walji AH. Cadaveric ultrasound imaging for training in

ultrasound-guided peripheral nerve blocks: lower extremity. Can J Anaesth. 2007;54:475-480.

Tsui BC, Finucane BT. The importance of ultrasound landmarks: a “traceback” approach using the

popliteal blood vessels for identification of the sciatic nerve. Reg Anesth Pain Med. 2006;31:481-

482.

Tsui BC, Ozelsel TJ. Ultrasound-guided anterior sciatic nerve block using a longitudinal approach:

“expanding the view.” Reg Anesth Pain Med. 2008;33:275-276.

an Geffen GJ, Bruhn J, Gielen M. Ultrasound-guided continuous sciatic nerve blocks in two children

with venous malformations in the lower limb. Can J Anaesth. 2007;54:952-953.

an Geffen GJ, Gielen M. Ultrasound-guided subgluteal sciatic nerve blocks with stimulating catheters

in children: a descriptive study. Anesth Analg. 2006;103:328-333.

PART 2: TRANSGLUTEAL AND SUBGLUTEAL APPROACH

General Considerations

The use of ultrasonographic guidance greatly expanded the options that practitioners have for

accomplishing the block of the sciatic nerve because the nerve can be imaged at several convenient

levels. With the transgluteal approach, the needle is inserted just distal deep to the gluteus maximus

muscle to reach the sciatic nerve. The sciatic nerve at the gluteal crease is readily identified in a

predictable anatomic arrangement, between two osseous landmarks (ischial tuberosity and the

greater trochanter) and beneath a well-defined muscle plane. The use of ultrasound visualization

decreases the need for the geometry and measurements that are required for the classic landmarkbased approaches. With the subgluteal approach, the nerve simply reached a few centimeters distally,

just below the level of the subgluteal crease where imaging is not interfered by the bones. The

preference of one approach over the other is made based on the patient’s anatomic characteristics and

personal preference.

Ultrasound Anatomy

At this transgluteal level, the sciatic nerve is visualized in the short axis between the two hyperechoic

bony prominences of the ischial tuberosity and the greater trochanter of the femur (Figure 39.2-1 and

39.2-2). The gluteus maximus muscle is seen as the most superficial muscular layer bridging the two

osseous structures, typically several centimeters thick. The sciatic nerve is located immediately deep

to the gluteus muscles, superficial to the quadratus femoris muscle. Often, it is slightly closer to the

ischial tuberosity (medial) aspect than the greater trochanter (lateral). At this location in the thigh, it

is seen as an oval or roughly triangular hyperechoic structure. At the subgluteal level, however, the

sciatic nerve is positioned deep to the long head of the biceps muscle and the posterior surface of the

adductor magnus.

FIGURE 39.2-1. Transsectional anatomy of the sciatic nerve at the transgluteal level. Sciatic nerve

(ScN) is seen between the greater trochanter of the femur and the ischium tuberosity, just below the

gluteus maximus (GMM) muscle.

FIGURE 39.2-2. An ultrasound image demonstrating the sonoanatomy of the sciatic nerve (ScN). The

ScN often assumes an ovoid or triangular shape and it is positioned underneath the gluteus muscle

(GMM) between the ischium tuberosity (IT) and femur.

Distribution of Blockade

Sciatic nerve block results in anesthesia of the entire lower limb below the knee, both motor and

sensory blockade, with the exception of a variable strip of skin on the medial leg and foot, which is

the territory of the saphenous nerve, a branch of the femoral nerve. In addition, both the transgluteal

and subgluteal approaches provide motor blockade of the hamstring muscles. The skin of the posterior

aspect of the thigh however, is supplied by the posterior cutaneous nerve of the thigh, which has its

origin from the sciatic nerve more proximal than the subgluteal approach. It is, therefore, unreliably

anesthetized with subgluteal block; however, it is of relatively little clinical importance. For a more

comprehensive review of the sciatic nerve distribution, see Chapter 1, Essential Regional Anesthesia

Anatomy.

Equipment

Equipment needed is as follows:

Ultrasound machine with curved (phase array) transducer (2–8 MHz), sterile sleeve, and gel

Standard nerve block tray (described in the equipment section)

One 20-mL syringe containing local anesthetic

A 100-mm, 21 to 22-gauge short-bevel insulated stimulating needle

Peripheral nerve stimulator

Sterile gloves

TIP

Although a linear transducer occasionally can be used for smaller size patients for this block, the

curved transducer permits the operator to visualize a wider field, including the osseous landmarks.

The ischial tuberosity and greater trochanter are rarely seen on the same image when using a linear

transducer.

Landmarks and Patient Positioning

Any patient position that allows for comfortable placement of the ultrasound transducer and needle

advancement is appropriate. Typically for either the transgluteal or subgluteal block, this involves

placing the patient in a position between the lateral decubitus and prone position (Figures 39.2-3 and

39.2-4). The legs are flexed in the hip and knee. When nerve stimulation is used simultaneously

(suggested), exposure of the hamstrings, calf, and foot is required to detect and interpret motor

responses. The round osseous prominences of the greater trochanter and ischial tuberosity are

palpated and, if desired, marked with a skin marker. Scanning is begun in the depression between the

two bones.

FIGURE 39.2-3. Patient position and transducer application for subgluteal approach to sciatic

block..

FIGURE 39.2-4. Transgluteal approach to sciatic block; patient position, transducer (curved)

placement and needle insertion.

GOAL

The goal is to place the needle tip adjacent to the sciatic nerve, below the fascial plane of the

gluteus muscles (thus, transgluteal technique) and to deposit 15 to 20 mL of local anesthetic until

its spread around the nerve is documented.

Technique

The description of the technique in this chapter will focus primarily on the transgluteal approach.

However, since the subgluteal approach is performed just a few centimeters more distal and it is

technically easier, the reader can easily perform either approach by using general guidelines provided

and referring to Figure 39.2-3, Figure 39.2-4, and algorithms at the end of the chapter. With the

patient in the described position, the skin is disinfected and the transducer is positioned so as to

identify the sciatic nerve (Figure 39.2-4). If the nerve is not immediately apparent, tilting the

transducer proximally or distally can help improve the contrast and bring the nerve “out” of the

background of the musculature. Often, the nerve is much better imaged after the injection of local

anesthetic (Figure 39.2-5). Alternatively, sliding the transducer slightly proximally or distally can

improve the quality of the image and allow for better visualization. Once identified, the needle is

inserted in-plane, typically from the lateral aspect of the transducer and advanced toward the sciatic

nerve. If nerve stimulation is used (1.0 mA, 0.1 msec), the passage of the needle through the anterior

fascial plane of the gluteus muscles often is associated with a motor response of the calf or foot. Once

the needle tip is positioned adjacent to the nerve (Figure 39.2-6A) and after careful aspiration to rule

out an intravascular needle placement, 1 to 2 mL of local anesthetic is injected to document the proper

injection site. Such injection often displaces the sciatic nerve away from the needle; therefore, an

additional advancement of the needle 1 to 2 mm toward the nerve may be necessary to ensure the

proper spread of the local anesthetic. When injection of the local anesthetic does not appear to result

in a spread around the sciatic nerve, additional needle repositions and injections may be necessary.

Assuring the absence of high resistance to injection is of utmost importance because the needle tip is

difficult to visualize on ultrasound due to the steep angle and depth of the needle placement.

FIGURE 39.2-5. Sciatic nerve (yellow arrows) as seen in the subgluteal position (linear transducer),

needle path (white arrows) and local anesthetic (turquoise arrows) in the intramuscular tunnel

surrounding the sciatic nerve.

FIGURE 39.2-6. (A) Ultrasound image demonstrating the simulated needle path to reach the sciatic

nerve (ScN) using an in-plane technique in transgluteal approach. The simulated needle (1) is shown

transversing the gluteus muscle with its tip positioned at the lateral aspect of the sciatic nerve. (B)

Needle path and distribution of local anesthetic (blue shaded area) to block the ScN through the

transgluteal approach.

TIPS

Never inject against high resistance to injection (>15 psi) because this may signal an intraneural

injection.

The ability to distinguish the sciatic nerve from its soft tissue surroundings often is improved after the

injection of local anesthetic; this can be used as a marker to confirm the proper identification of the

nerve when injection begins.

In an adult patient, 15 to 20 mL of local anesthetic is usually adequate for successful blockade of

sciatic nerve (Figure 39.2-6). Although a single injection of such volumes of local anesthetic suffices,

it may be beneficial to inject two to three smaller aliquots at different locations to ensure the spread

of the local anesthetic solution around the sciatic nerve. The block dynamics and perioperative

management are similar to those described in Chapter 19.

Continuous Ultrasound-Guided Subgluteal Sciatic Block

The goal of the continuous sciatic block is similar to the non-ultrasound-based techniques: to place

the catheter in the vicinity of the sciatic nerve between the gluteus maximus and quadratus femoris

muscles. The procedure consists of three phases: needle placement, catheter advancement, and

securing the catheter. For the first two phases of the procedure, ultrasound visualization can be used

to ensure accuracy in most patients. The needle typically is inserted in-plane from the lateral to

medial direction and underneath the fascia to enter the subgluteal space.

Advancement of the needle until the tip is adjacent to the nerve and deep to the gluteus maximus

fascia should ensure appropriate catheter location. Proper placement of the needle also can be

confirmed by obtaining a motor response of the calf or foot at which point, 4 to 5 mL of local

anesthetic is injected. This small dose of local anesthetic serves to ensure adequate distribution of the

local anesthetic as well as to make the advancement of the catheter easier. This first phase of the

procedure does not significantly differ from the single-injection technique. The second phase of the

procedure involves maintaining the needle in the proper position and inserting the catheter 3 to 5 cm

beyond the needle tip into the subgluteal space in the vicinity of the sciatic nerve. Insertion of the

catheter requires an assistant when it is done under ultrasound guidance. Alternatively, the catheter

can be inserted using a longitudinal view. With this approach, after successful imaging of the sciatic

nerve in the cross-sectional view, the transducer is rotated 90° so that the sciatic nerve is visualized

in the longitudinal view. However, this approach requires significantly greater ultrasound imaging

skills.

The catheter is secured by either taping it to the skin or tunneling. A common infusion strategy

includes ropivacaine 0.2% at 5 mL/minute with a patient-controlled bolus of 5 mL/hour.

SUGGESTED READING

Abbas S, Brull R. Ultrasound-guided sciatic nerve block: description of a new approach at the

subgluteal space. Br J Anaesth. 2007;99:445-446.

Barrington MJ, Lai SL, Briggs CA, Ivanusic JJ, Gledhill SR. Ultrasound-guided midthigh sciatic nerve

block-a clinical and anatomical study. Reg Anesth Pain Med. 2008;33:369-376.

Bruhn J, Moayeri N, Groen GJ, et al. Soft tissue landmark for ultrasound identification of the sciatic

nerve in the infragluteal region: the tendon of the long head of the biceps femoris muscle. Acta

Anaesthesiol Scand. 2009;53:921-925.