A quantitative Allen's test.

Allen's test has been performed quantitatively by measuring digital systolic pressure during compression of the radial or ulnar artery at the wrist. The reduction of pressure in normal subjects was less than 25 per cent. Insufficiency of the arterial supply to the hand from the radial artery, the ulnar artery or the palmar arcades can easily be diagnosed from an abnormal reduction in digital systolic pressure during arterial compression.