Journal of Applied Physiology, Vol 59, Issue 3 722-731, Copyright © 1985 by American Physiological Society
Noninvasive Doppler determination of cardiac output during submaximal and peak exercise
J. G. Shaw, E. C. Johnson, W. F. Voyles and E. R. Greene
We compared pulsed Doppler (PD) measurements of stroke volume (SV) and
cardiac output (CO) as a function of work load with previously reported
values that were obtained by standard invasive methods. Suprasternal notch
measurements of Doppler-shifted frequency (delta f) were obtained from the
ascending aorta and SV calculated with the Doppler equation and an
independent measurement of aortic diameter. Motion artifacts were minimized
with the aid of a restraining table cycle ergometer. Signal aliasing was
accommodated with manual summation of delta f waveforms. A total of 207
determinations were made in 10 sitting subjects exercising to exhaustion.
Linear regression analysis of CO vs. work load was significant (P less than
0.001). The correlation coefficient (r = 0.95) and standard error of
estimate value (1.21 1/min) were similar to values from the literature.
Absolute values of CO and SV underestimated the literature values across
all work loads. Technical reproducibility was assessed by comparing with
paired t tests the differences between 65 duplicate serial measurements of
CO and SV at rest and exercise. No significant differences (P less than
0.001) were found. We concluded that PD-determined SV and CO are
reproducible and correlate linearly with work load in a manner consistent
with reported invasive techniques. Thus the PD method appears suitable for
use during submaximal and peak exercise.
