3. When performing radial or ulnar cannulation, avoid

excessive hyperextension of wrist, because this may

result in occlusion of artery and a false-positive Allen

test (18) and has been associated with median nerve

conduction block (19).

4. Leave all fingertips/toes exposed so that circulatory status may be monitored. Examine limb frequently for

changes in perfusion.

5. Never ligate artery.

6. Take care not to introduce air bubbles into cannula while

assembling infusion system or taking blood samples.

7. Make sure that a continuous pressure waveform tracing

is displayed on a monitor screen at all times.

8. Be aware that the blood pressure measured in the lower

extremity may be 5 to 20 mm Hg higher than in the

upper extremity, and the reading may be delayed by

one tenth of a second (17).

9. Do not administer a rapid bolus injection of fluid via

line, because there is a danger of retrograde embolization of clot or air (20). Flush infusion after sampling

should be:

a. Minimal volume (0.3 to 0.5 mL)

b. Injected slowly

10. To reverse arteriospasm, see Chapter 34.

11. Use cannula for sampling only; no fluids other than

heparinized saline flush solution should be administered via cannula.

12. Remove cannula at first indication of clot formation or

circulatory compromise (e.g., dampening of waveform

on monitor). Do not flush to remove clots.

13. Inspect cannula insertion site at least daily.

a. If signs of cellulitis are present, remove the cannula

and send the cannula tip for culture. Also, send a

wound culture if there is inflammation at the cutdown site.

b. Obtain a blood culture from a peripheral site if signs

of sepsis are present.

c. Inspect the area distal and proximal to the insertion

site for blanching, redness, cyanosis, or changes in

temperature or capillary refill time.

14. Remove cannula as soon as indications no longer exist.