Reactive hyperemia in the human finger.

Reactive hyporcmia in the finger was investigated in 16 experiments on 5 normal subjects, using venous occlusion plethysmography. Since the flow is so variable from moment to moment, the simultaneous "corrected" flow in a control finger, not occluded, was subtracted from tho flow in the test finger, so the difference gave the effect of occlusion free from fluctuations of central origin. The absolute amount and the duration of extra blood flow increased with the (jeriod of occlusion. The percentage of the calculated "blood flow debt" repaid was variable, with a mean of 51 per cent ± 36. S.D. (CTM ± 6 per cent). This is greatly in excess of nutritional debt of the skin.