Noninvasive estimation of brachial artery blood flow: a clinical application of ultrasonic instrumentation.

Ultrasonic instrumentation based on the Doppler phenomenon fulfills one requirement for a blood flowmeter - that it sense a variable which is a function of the volume of blood moved through the blood vessel in situ. In this study, a segment of the blood flow velocity waveform recorded noninvasively from the brachial artery in the antecubital fossa was used as a basis for estimating the mean velocity of a bolus of blood passing through the incident sound beam of a Doppler instrument. A stroke flow index - cubic centimeters of blood per pulse wave propagation - was calculated as the product of the mean velocity and cross-sectional lumen area of the brachial artery. The method used in these experiments proved to be reproducible in volunteer subjects. The estimated minute flow ranged from 32 to 95 ml/min in these normal subjects. Serial measurements before and after open-heart operations in 64 patients demonstrated a valuable clinical application. A significant reduction in the brachial artery stroke flow index was recorded at some time postoperatively in 21 of these patients. The brachial artery stroke flow index determined non-invasively has potential value as an objective estimate of cardiovascular instability.