Arterial blood can be obtained by direct arterial puncture most usually at the wrist (radial artery) But Allen's test is performed as a preventive measure for complications.
Allen's Test
- Elevate the hand and make a fist for approximately 30 seconds.
- Apply pressure over the ulnar and the radial arteries occluding both (keep the hand elevated).
- Open the hand which will be blanched.
- Release pressure on the ulnar artery and look for perfusion of the hand (this takes under eight seconds).
- If there is any delay then it may not be safe to perform radial artery puncture.
It is also called a modified Allen test or Allen's Maneuver Test.
