Method and system for non-invasive ultrasound Doppler cardiac output measurement

A method and system for the noninvasive measurement of cardiac output of a mammalian patient on a real time, beat-by-beat basis as a combined function of the cross-sectional area of the ascending aorta and the systolic velocity of blood flow therethrough is comprised of the steps of and apparatus for pulsedly insonifying the ascending aorta of the patient with repetitive, intermittent ultrasonic energy propagating through the patient's cardiac window; receiving pulses of ultrasonic energy reflected from the anatomical structure within the first insonification zone, including energy reflected from the aortic walls and characteristic of the dimensional separation thereof; developing an aortic diameter signal indicative of dimensional separation; computing the cross-sectional area of the ascending aorta therefrom; then continuously insonifying the ascending aorta with uninterrupted ultrasonic energy; receiving a Doppler-shifted ultrasonic energy signal reflected from pulsatile blood flow through the ascending aorta, and characteristic of systolic velocity of blood flow; subjecting the systolic velocity signal to a frequency spectrum analysis at a predetermined signal sampling rate to yield a velocity component profile signal; integrating the velocity component profile signal over time; computing systolic volume as a combined function of cross-sectional area and the systolic velocity integral for each of n cardiac cycles; and, computing cardiac output as the time-averaged sum of systolic volumes for the n periods.