Extremity blood flow in man: comparison between strain-gauge and capacitance plethysmography.

Metabolic studies with substrate limb flux determinations require an accurate and simple method for measuring blood flow through the extremity. Two common, noninvasive methods used in recent studies are strain-gauge and capacitance venous occlusion plethysmography. The values obtained for forearm blood flow by these two methods are highly correlated in normal resting and seriously ill patients. The use of a fixed percentage of cardiac output as a measure of extremity flow was not indicative of the measured flow by either capacitance or strain-gauge plethysmography. Capacitance and strain-gauge plethysmography are comparable, noninvasive indicators of change in extremity blood flow in humans.