What happens after the ulnar artery is released in the modified Allen test?

In the context of the modified Allen test, after the ulnar artery is released, the expected outcome is that the skin color in the area supplied by the radial artery should return to normal. This indicates adequate collateral blood flow from the ulnar artery to the hand. When the ulnar artery is compressed and the radial artery is left open, it limits blood flow to the hand. Once the ulnar artery is released, the restored blood flow from the ulnar artery should rapidly perfuse the area, causing the skin color to revert to its normal state as oxygenated blood reaches the tissues.

This returning of color is a sign of sufficient blood supply and is critical in assessing the vascular supply to the hand before any procedures that may occlude the radial artery, such as a transradial catheterization. The skin color returning to normal confirms that the ulnar artery is providing adequate collateral circulation, ensuring that the hand remains well-oxygenated.

Other options present scenarios that do not align with the expected physiological response. For instance, tingling sensations may occur due to nerve compression or temporary changes in blood flow, but this is not a definitive result of the test. The radial artery being occluded in this context is not relevant