Transcutaneous Doppler method of measuring cardiac output--II. Noninvasive measurement by transcutaneous Doppler aortic blood velocity integration and M mode echocardiography.

In 15 patients with acute myocardial infarction (group I) and in 14 patients undergoing routine cardiac catheterization (group II) cardiac output values obtained by multiplying the 1 minute sum of the systolic integral of aortic blood flow velocity by the average systolic diameter of the aortic root were compared with values obtained with the thermodilution and Fick methods, respetively. Patients in group I were studied under various hemodynamic conditions, whereas those in group II were studied in the baseline state conditions, whereas those in group II were studied in the baseline state only. In group I, the correlation between the two methods was excellent (r values ranged from 0.96 to 0.99) except in one severely anemic patient whose Doppler signals were noisy, but at heart rates exceeding 150 beats/min it was not as good. In group II, the correlatin between the two methods was r = 0.96 with a standard error of the estimate of 0.226 liter. The Doppler method is totally noninvasive and is useful for monitoring changes in cardiac output in patients with acute myocardial infarction.