What is the purpose of the Allen test?

The Allen test is specifically designed to assess the patency of the radial and ulnar arteries. This is particularly important before undergoing procedures such as arterial sampling or the placement of a radial arterial line, where it is crucial to ensure that there is adequate blood flow and collateral circulation to the hand.

During the test, a healthcare provider will compress the radial and ulnar arteries while the patient makes a fist. Upon releasing the pressure on one of the arteries, the filling of the palm and fingers is observed. A quick return of color indicates good blood flow through the artery that was released, demonstrating its patency. If the blood flow is inadequate, this suggests a potential issue with that artery, which can have significant implications for surgical decisions or interventions.

Measuring blood pressure, assessing heart rate, and checking for blood clots are unrelated to the primary focus of the Allen test, which is centered on arterial circulation specifically in the context of the radial and ulnar arteries.