Plethysmography without venous occlusion for measuring forearm blood flow: comparison with venous occlusive method.

Limb blood flow is widely used as an indicator of the human vascular properties. There are only few non-invasive methods for its measurement such as venous occlusion plethysmography. However, several authors have questioned its validity.

Blood flow measurement from plethysmographic pulse waves without venous occlusion.

An air plethysmograph with a sensitive phototransducer was constructed so that plethysmographic volume-change pulsations could be displayed in detail without using venous occlusion. Software was developed to allow analysis of the pulses using a modification of the backward extrapolation technique. This allowed calculation of the forward arterial blood flow and noninvasive derivation of the resting arterial flow waveform.

Plethysmographic curve analysis and response to exercise in normal subjects, hypertension, and cardiac failure.

Occlusion plethysmographic recordings were obtained on 26 subjects prior to and immediately following repeated venous occlusions. A simple method of approximating the curve shape by 2 straight lines is described. The results indicate that, following an initial occlusion, the height of subsequent curves is reduced and the angulation between the 2 lines approximating the curves changes in a way that indicates that the principal mechanism is venous shunting.