What test evaluates the patency of the palmar arch?

The Allen test is specifically designed to evaluate the patency of the palmar arch, which is crucial for assessing blood flow to the hand. This test involves occluding both the radial and ulnar arteries at the wrist while the patient makes a fist. When the patient opens the fist, if the palm flushes normally and quickly, it indicates that the ulnar artery is supplying adequate blood flow through the palmar arch. This test helps to confirm that there is no significant obstruction in the arteries supplying the hand.

Understanding this test is important, particularly in situations where vascular access is required, such as when considering procedures like arterial catheterization. The Allen test can provide essential information about the collateral circulation and the adequacy of blood supply to the hand before any medical interventions are performed.