and emergency department procedural sedation and analge ­

sia: a consensus-based clinical practice advisory. Ann Emerg

Med. 2007;49:454-46 1.

Miner JR. Procedural sedation and analgesia. In: Tintinalli JE,

Stapczynski JS, Ma OJ, Cline DM, Cydulka, RK, Meckler GD.

Tintinalli's Emergency Medicine: A Comprehensive Study

Guide. 7th ed. New York, NY: McGraw-Hill, 20 1 1:283-29 1.

Lumbar Puncture

Pilar G uerrero, MD

Key Points

• Knowledge of anatomical landma rks and proper steri le

techn ique are important when performing a lumbar

puncture (LP).

• Absolute contraindications to LP are skin infection over

puncture site and a brain mass causing increased intracranial pressure.

INDICATIONS

Lumbar puncture (LP) is performed in the emergency

department (ED) primarily to diagnose central nervous

system (CNS) infections (ie, meningitis) and subarachnoid

hemorrhage (SAH). It may also be performed to relieve

cerebrospinal fluid (CSF) pressure and to confirm the

diagnosis of idiopathic intracranial hypertension (pseudo ­

tumor cerebri). Other indications include the diagnosis of

demyelinating or inflammatory CNS processes and carcinomatous/metastatic disease.

CONTRAINDICATIONS

Absolute contraindications for performing a LP include

infected skin over the puncture site, increased intracranial

pressure (ICP) from any space-occupying lesion (mass,

abscess), and trauma or mass to lumbar vertebrae. A noncontrast head computed tomography ( CT) scan should be

performed to rule out an intracranial mass before performing an LP in the following clinical situations: altered

mental status, focal neurologic deficits, signs of increased

ICP (papilledema), immunocompromise, age >60 years,

or recent seizure. Relative contraindications include

patients who have bleeding diathesis or coagulopathy

(Table 5-1).

16

• Herniation is the most serious compl ication of a LP,

whereas post-LP headache is most common.

Table S-1. Contraind ications to lumbar pu ncture.

Skin infection near the site of lumbar puncture

Central nervous system lesion causing increased intracranial pressure

or spinal mass

Platelet count <20,000 mm3 is an absolute contraindication; platelet

counts >50,000 mm3 are safe for lumbar puncture*

International normal ized ratio 2:1 .5*

Administration of unfiltered heparin or low-molecular-weight heparin

in past 24 hours*

Hemophil ia, von Willebrand disease, other coagulopathies''

Trauma to lumbar vertebrae

···correct clotting factor and/or platelet levels before lumbar puncture.

Reprinted with permission from Ladde JG. Chapter 1 69. Central Nervous

System Procedures and Devices. In: Tintinalli JE, Stapczynski JS, Cline OM,

Ma OJ, Cydulka RK, Meckler GO, eds. Tintinalli's Emergency Medicine:

A Comprehensive Study Guide. 7th ed. New York: McGraw-Hill, 201 1.

EQUIPMENT

Most EDs have a commercially available LP kit, which contains a 20-gauge spinal needle, 22- and 25-gauge needles

for lidocaine administration, 4 collection tubes, stopcock

LUMBAR PUNCTURE

.A. Figure 5-1. Lumbar puncture kit.

and manometer with extension tubing, sterile drapes, skincleansing sponges, and lidocaine (Figure 5- 1). Smaller

spinal needles may be used ( 22, 25 gauge) and may

decrease the incidence of post-LP headache; however, a

22 or larger gauge needle must be used to determine an

accurate opening pressure. Other required supplies include

additional 1% lidocaine without epinephrine, povidoneiodine (Betadine), and sterile gloves.

PROCEDURE

Lumbar puncture is an invasive procedure. Always perform

a neurologic examination before LP. Explain the proce ­

dure, risks and benefits, and potential complications and

obtain written consent.

Level of i l iac crests

Assemble all equipment and have it within easy reach.

Position the patient in a lateral decubitus position with

hips and knees flexed and the upper back arched. This

will allow better opening of the interlaminar spaces.

Make sure the patient's shoulders, back, and hips are perpendicular to the stretcher. Alternatively, the patient may

be in a sitting position, leaning forward and resting their

arms on a tray stand. The latter may work well for

patients who are obese, have degenerative joint disease, or

have problems breathing. However, an accurate opening

pressures can only be obtained with the patient in the

lateral decubitus position.

Next, identify your landmarks by palpating the top of

the posterior superior iliac crests, moving your fingers

medially, as if drawing an imaginary line toward the spine.

This should be at the L4 interspace level. Palpate the spinous processes and identify the 13-14 and the 14-15

interspace. Either of these spaces can be used for the procedure (Figure 5-2).

Open the sterile tray and pour Betadine into the

empty receptacle in the kit. Put on the sterile gloves .