Arterial Lines

Choosing the Right Limb

On this page:Allen's Test


    • Do

    • Try to use the radial artery if possible
    • Perform Allen’s test prior to inserting the needle
    • Don't

    • Absolutely do not use the same arm as an AV fistula
    • Don’t use the radial artery on a limb with a fractured wrist
    • Avoid areas with inadequate collateral circulation (e.g. peripheral vascular disease)
    • Avoid inserting a needle through cellulitis, burns or oedema

Allen's Test

  • A clinical test used to determine the patency of the radial and ulnar arteries, used as a predictor of distal ischaemia risk post radial arterial cannulation or catheterisation.
    • How to Perform

    • Ask the patient to clench their fist, and apply pressure to both the radial and ulnar arteries. Ask the patient to relax their hand, looking for blanching - if the hand does not blanch then both vessels are not occluded. Release pressure on the ulnar nerve, and look for flushing as the hand is reperfused.
    • Interpretation

    • If the hand does not flush in 10-15 seconds then the ulcer circulation is inadequate, a contraindication to radial puncture on the limb in question.
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