Admittance plethysmography for accurate measurement of human limb blood flow

Publisher Website
Google Scholar
Abstract
The accuracy of electrical admittance plethysmography for measuring blood flow in human forearms and calves was evaluated by comparison with conventional water displacement plethysmography. Simultaneous records of both plethysmograms showed the time courses of both were almost identical, the ratio of the volume change, measured by water displacement plethysmography, to the admittance change was nearly equal to the blood resistivity calculated from the hematocrit value, and both methods gave practically the same values for blood flow rates and volume changes when an appropriate value for blood resistivity was used in the admittance plethysmography. The admittance change following venous occlusion in the human limb segment is mainly due to the change in the volume of the segment caused by accumulation of blood inflow. The Nyboer parallel conductor model is acceptable for human limb segments. The accuracy of the method is improved by correcting the blood resistivity with respect to the hematocrit value. If carefully used, electrical admittance plethysmography is a useful substitute for the more direct water displacement plethysmography, being technically much simpler than the latter.

This publication has 3 references indexed in Scilit: