Effects of Positive Tissue Pressure on Blood Flow of the Finger

Abstract

The venous-occlusion plethysmograph method was used on 5 subjects in 8 expts. to measure the blood flow in the finger under positive tissue pressure. Application of a steady positive pressure to the finger (equivalent to raising the tissue pressure) reduced the blood flow. When a critical tissue pressure, which was still less than the arterial pressure, was applied, blood flow became zero. The difference between the arterial pressure and the tissue pressure which caused cessation of flow was taken as the critical closing pressure. When the subjects were taken from vasoconstriction to full vasodilation by heat, the range of the critical closing pressure for the finger was from 10 to 56 mm. Hg. There is a highly significant correlation between the level of the critical closing pressure in the finger and the resistance to flow at high pressure. This is interpreted to mean that the vessels which close are the arterioles, which contribute the major part of the resistance to flow.