The American journal of cardiology
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Comparative Study
Noninvasive measurement of cardiac output during surgery using a new continuous-wave Doppler esophageal probe.
The ability of a new continuous-wave Doppler esophageal probe to measure cardiac output noninvasively during surgery under general anesthesia was tested and compared with simultaneously measured thermodilution cardiac output. A Doppler computer, calibrated for the aortic diameter and the transcutaneously measured cardiac output from the suprasternal notch, computed the Doppler cardiac output from the descending aortic blood flow velocity signal. A total of 246 paired Doppler cardiac output and thermodilution cardiac output measurements were made in 14 patients during surgery. ⋯ There was a correlation between the 2 measurements over a range of cardiac output values (r = 0.76, Doppler cardiac output = 0.93 x thermodilution cardiac output +0.7, standard error of the estimate = 1.76). Reproducible measurements of Doppler cardiac output were obtained during intraobserver (mean difference 0.64 +/- 0.52 liter/min) and interobserver (mean difference 0.41 +/- 0.36 liter/min) studies (n = 8). Cardiac output measurement by the Doppler esophageal probe could be used for hemodynamic monitoring during surgery in selected patients with cardiopulmonary disease.