A comparative study of cardiac output measurement by dye dilution and pulsed Doppler ultrasound.

Dye dilution was compared with pulsed doppler for the measurement of cardiac output in eighteen children being ventilated after cardiac surgery. The mean difference between the two techniques was -0.04/min (dye minus doppler) with 95% confidence limits of 0.25 l/min and -0.33 l/min over a cardiac output range 0.27-6.12 l/min; this difference is not significant. Calculation of the product-moment correlation coefficient showed a close relationship between the dye dilution and doppler methods with r = 0.97. Pulsed doppler is a new noninvasive technique that can be used instead of dye dilution for the measurement of cardiac output in co-operative or anaesthetised children.