Continuous and intermittent cardiac output measurement: pulmonary artery catheter versus aortic transpulmonary technique.

BACKGROUND: Cardiac output (CO) can be measured intermittently by bolus thermodilution methods in the pulmonary artery (COpa) or in the aorta (COart). A continuous thermodilution method (CCO) and a method for continuous estimation using the arterial pulse wave (PCCO) are also available. METHODS: We compared two methods of intermittent CO measurements in patients during liver transplantation: COpa, regarded as the current clinical standard, and an aortic transpulmonary thermodilution technique (COart) performed with the PiCCO system. We also compared CCO and PCCO. Measurements were made in 62 patients at three stages: after the induction of anaesthesia, after caval clamping phase, and at the end of surgery. We used Bland-Altman and correlation analysis. RESULTS: We found close agreement between the techniques. Mean bias between COart and COpa and PCCO and CCO was 0.15 (2SD of differences between methods=1.74) litre min(-1) and -0.03 (1.75) litre min(-1), respectively. Mean bias between CCO and COpa and PCCO and COpa was 0.02 (1.48) litre min(-1) and 0.04 (1.69) litre min(-1), respectively. CONCLUSIONS: Measurement with the aortic transpulmonary thermodilution technique gives continuous and intermittent values that agree with the pulmonary thermodilution method.