Measurement of cardiac output with the Quantascope, a novel Doppler device: comparison with thermodilution.

The Quantascope is a novel non-imaging echo-Doppler device designed to measure cardiac output. We have compared this device with thermodilution. Twenty-five patients with suspected coronary artery disease undergoing diagnostic coronary arteriography simultaneously had cardiac output measured with the Quantascope and with thermodilution. Doppler systematically underestimated cardiac output, when compared with thermodilution, by a mean (SD) of 0.9 (1.5) l.min-1 (P < 0.01). The cardiac output derived by the Doppler technique did not correlate with that derived by thermodilution (r = 0.36, P = NS). Compared with the currently accepted reference technique of thermodilution, we found measurement of cardiac output by the Quantascope to be inaccurate: this contradicts previous reports.