Noninvasive ultrasonic estimation of brachial artery blood flow

Ultrasonic instrumentation based on the Doppler phenomenon fulfills the requirement that a blood flowmeter should sense a variabel which is a function of the volume of blood moved through a blood vessel in situ. The blood flow velocity waveform recorded noninvasively from the brachial artery in the antecubital fossa was used as basis for quantitatively estimating a stroke flow index. The method used in these experiments was reproducible in 31 volunteer subjects studied; the first and second brachial artery stroke flow indices determined on different days had a correlation coefficient of 0.909. The calculated minute flow index ranged from 32 to 95 ml in these subjects. A clinical application was explored by making serial measurements before and after operation in 64 patients submitting to 68 open heart operations. A significant reduction in the brachial artery blood flow velocity was recorded postoperatively in 21 of these patient. The brachial artery stroke flow index has potential value as an objective measure of cardiovascular instability.