A client is scheduled for blood to be drawn from the radial artery for an ABG determination. Before the blood is drawn, an Allen’s test is performed to determine the adequacy of the:
A. Popliteal circulation
B. Ulnar circulation
C. Femoral circulation
D. Carotid circulation
Correct Answer: B. Ulnar circulation
Before radial puncture for obtaining an ABG, you should perform an Allen’s test to determine adequate ulnar circulation. Failure to determine the presence of adequate collateral circulation could result in severe ischemic injury to the hand if damage to the radial artery occurs with arterial puncture.
Option A: The radial artery is easily palpable. The need for this test arises from the inability to palpate the ulnar artery. Because the ulnar artery cannot be palpated, its patency cannot be assessed, and therefore, collateral circulation of the hand cannot be confirmed.
Option C: If the radial artery needs to be cannulated or catheterized and there is a risk for thrombosis, then the Allen test can help confirm that the hand will maintain adequate blood flow through the ulnar artery and collaterals in the event it becomes occluded.
Option D: The AT test is used to ensure collateral circulation of the hand. The test can be used as a diagnostic tool for any number of disorders with a reduced vascular flow to the arm or after hand surgery. It is more commonly used to assess collateral flow to the hand through the ulnar artery when the radial artery is going to be used for arterial punctures for drawing blood gases, cannulation for placement of arterial lines, catheterization, or radial artery harvest for bypass surgeries.
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