[Measurement of cardiac output after cardiac surgery: validation of a partial carbon dioxide rebreathing (NICO) system in comparison with continuous thermodilution with a pulmonary artery catheter].

UNLABELLED: Cardiac output is usually monitored with a pulmonary artery catheter. However, because that method is not free of risk, devices have been designed in recent years to measure cardiac output in a way that is minimally invasive or fully noninvasive. Among such devices is the NICO monitor, which is based on a modified Fick equation (partial CO2 rebreathing). OBJECTIVE: To compare the accuracy of cardiac output measurements from the NICO monitor to measurements obtained by continuous thermodilution with a pulmonary artery catheter. MATERIAL AND METHODS: A nonprobabilistic, consecutive sample of 20 patients was enrolled in the early postoperative period after elective cardiac surgery (coronary or valve procedures) in the recovery ward. Seven measurements of cardiac output were taken simultaneously with each method in each patient. RESULTS AND CONCLUSIONS: Cardiac output estimated by the partial CO2 rebreathing method was lower than the measurement obtained by the pulmonary artery catheter. The percentage error between the 2 methods was 37%, indicating that the NICO monitor can not substitute for the traditional method. The better correlation found between normal-to-low cardiac output values and the absence of side effects of using the NICO method suggest that it might be indicated for detecting low cardiac output after cardiac surgery, especially when the risk-benefit ratio does not favor using a pulmonary artery catheter.