What is the primary purpose of the Allen test?

The primary purpose of the Allen test is to assess the patency of the palmar arch. This test evaluates the blood supply to the hand, specifically determining whether the ulnar and radial arteries are functioning properly and ensuring adequate blood flow through the palmar arch. By occluding one of the arteries and observing the time it takes for the hand to regain its normal color upon release, the test provides insight into the presence of collateral circulation and the overall adequacy of the arterial supply.

This assessment is particularly important before procedures such as radial artery catheterization or harvesting for a bypass graft, as it confirms that there is sufficient blood flow to the hand if one of the arteries is compromised. The test’s design allows for a straightforward evaluation of arterial function, pivotal in clinical situations involving vascular access or potential compromise in blood supply.