Excess cumulative blood flow and repayment during reactive hyperemia in human cutaneous tissue.

The influence of duration of vascular occlusion upon the reactive hyperemic response in human cutaneous tissue was studied in 6 subjects. Blood flow in cutaneous tissue was measured dorsally on the distal phalanx of the second finger by the local 133Xenon washout technique. Post-occlusive blood flow, calculated from the steepest part of the 133Xenon washout curve just after release of vascular occlusion, reached a maximum value when duration of vascular occlusion was 12 min. However, excess cumulative blood flow, i.e. the integrated blood flow during reactive hyperemia minus integrated pre-ischemic blood flow for a period corresponding to the duration of the reactive hyperemic response, increased with increasing duration of vascular occlusion from 3 to 24 min. Fractional repayment, i.e. excess cumulative blood flow divided by pre-ischemic blood flow times duration of vascular occlusion, was not correlated significantly to duration of vascular occlusion. However, there was a significant inverse correlation between fractional repayment and pre-occlusive blood flow, indicating that, besides metabolic factors, pre-ischemic blood flow in cutaneous tissue is influenced by other factors, such as heat regulation.