Allen's test
OtherThe Allen's test checks to make sure that radial and ulnar arteries that supply blood to the hand are not blocked. A pulse oximeter is placed on the index finger of the hand. The subject is asked to make a fist for 10 seconds.At this time, pressure is applied over the ulnar and radial arteries as to occlude (block) both of them. The pulse oximeter reading will begin to fall. Radial arterial pressure is then released. If the artery is patent (working), the pulse oximeter reading will begin to rise.