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a test for occlusion of radial or ulnar arteries: the patient makes a tight fist so as to express the blood from the skin of the palm and fingers; the examiner makes digital compression on either the radial or ulnar artery. Failure of blood to return to the palm and fingers when the hand is opened indicates obstruction of the blood flow in the artery that has not been compressed. Either this test or a doppler ultrasound examination should always be performed prior to insertion of a radial artery line.
Allen's testA clinical test used to evaluate ulnar-artery patency before radial-artery cannulation or radial-artery harvesting for coronary-artery bypass grafting.
Method Simultaneous compression of both the radial and ulnar arteries, followed by exsanguination of blood from the palm by repeated clenching and unclenching of the fist. The pressure over the ulnar artery is then released while maintaining pressure over the radial artery. A 5–6 second delay in flushing of the palm suggests abnormal ulnar-artery patency.