the radial and ulnar arteries using your fingers. Ask the

patient to clench the fist to increase venous drainage

from the hand for approximately 30 seconds. Ask the

patient to open the hand, which should be noticeably

pale. At this point, release only the ulnar artery. Rapid

return of color signifies adequate collateral flow.

Although the necessity of the test for arterial puncture is

questioned, common sense dictates that if collateral flow

in one wrist is noticeably decreased compared with the

other, the wrist with better collateral flow should be

accessed. In the absence of good collateral flow in both

wrists, the necessity of the procedure should be weighed

against the remote risk of serious vascular injury and

distal extremity ischemia.

The radial artery is easily palpated in a majority of

patients. It runs down the radial aspect of the forearm,

generally located between the styloid process of the

radius and the flexor carpi radialis tendon at the

.A. Figure 2-2. Position of the forea rm for puncture of

the radial artery. A kidney basin or rol led towel may

be helpful to hold the patient's wrist in this position.

proximal crease of the wrist. The patient's wrist should

be extended to bring the artery to a more superficial

position. A kidney basin or rolled towel as well as tape

may be helpful to hold the patient's wrist in this posi ­

tion ( Figure 2-2). The skin overlying the artery should

be cleaned. The skin and immediate subcutaneous

tissue should then be appropriately anesthetized. The

authors recommend massaging the area or letting it rest

for 1-2 minutes for the anesthetic to take complete

effect. This time may be used to prepare your other

equipment.

After locating the impulse of the artery with the nondominate hand, take the syringe and needle in your dominate hand and slowly advance the needle toward the

impulse at a 30- to 45-degree angle proximally toward the

patient. If the impulse is difficult to detect, an ultrasound

or Doppler may be helpful to locate the artery (Figure 2 - 3) .

Some practitioners use a direct 90-degree angle to the skin,

but this is largely a matter of preference. When the artery

is accessed, blood will passively fill the syringe. It should

not be necessary to draw back on the syringe. Pulsatile or

bright red blood signals the correct vessel has been

accessed; however, this may not be apparent in the criti ­

cally ill patient. If blood is not obtained, withdraw the

needle to just below the skin and reattempt the procedure

after slight adjustments have been made. Do not move the

needle in an arc deep in the skin, as this risks damage to

the vascular structures.

After blood is collected, the needle should be removed

and disposed of appropriately. Remove air from the syringe

and place the syringe cap, ensuring that blood contacts the

cap. Maintain pressure over the arterial site for approxi ­

mately 5 minutes to prevent development of a hematoma,

and dress the wound appropriately.

CHAPTER 2

Radial vein

Tendon

Radial vein

8