Measurement of postoperative cardiac output by thermodilution in pediatric and adult patients.

Serial cardiac output determinations were made by the thermodilution technique in 51 patients by means of a No. 2 Fr. thermistor catheter placed directly into the pulmonary artery at cardiac operation. Correlations were determined prospectively between thermodilution measurements of cardiac output and other commonly used indirect clinical parameters. Serial indicator dye-dilution curves were performed in 24 of these patients and compared with simultaneous thermodilution measurements. A high correlation (r = 0.97) was noted between dye curve measurements of cardiac output and thermal measurements. Statistically significant correlations were also seen between cardiac output and both the quality of the peripheral pulses and the duration of cardiopulmonary bypass, but no significant correlations were found between the measured cardiac outputs and other variables. This study confirms the necessity for direct measurement of cardiac output for its accurate assessment.