To investigate in a direct comparison accuracy and precision of continuous cardiac output measurements assessed by continuous pulmonary artery thermodilution technique (TDCCO), continuous pulse contour analysis (PCCO), and noninvasive partial CO(2)-rebreathing technique (NICO) in patients after coronary artery bypass grafting (CABG) during the postoperative period. Prospective, controlled clinical study. University hospital. Twenty-two patients undergoing elective CABG surgery. Hemodynamic measurements were performed after admission to the ICU and in sequence every 2 hours during the subsequent 6-hour period. Simultaneously, cardiac output (CO) was measured using a TDCCO, PCCO, and NICO. After the continuous cardiac output measurements were read, bolus thermodilution-derived cardiac output was obtained from thermodilution curves detected in the pulmonary artery (TDBCO(pa)). Four intermittent consecutive boli consisting of 10 mL of ice-cold saline were randomly injected over the ventilatory cycle. The comparison between the continuous cardiac output measurement methods TDCCO versus PCCO showed a bias of -0.12 L/min, between TDCCO versus NICO -0.17 L/min, and between PCCO versus NICO -0.44 L/min. The comparison to the reference technique between TDBCO(pa) versus TDCCO revealed a bias of -0.28 L/min, between TDBCO(pa) versus PCCO -0.40 L/min, and between TDBCO(pa) versus NICO -0.64 L/min. The results of this clinical investigation show agreement between TDCCO and PCCO to satisfy clinical requirements in a setting of postoperative patients after cardiac surgery. In contrast, the NICO monitor is of very limited use in these patients. Copyright 2003 Elsevier Inc. All rights reserved.