Continuous Arterial Pressure Waveform Analysis Accurately Detects Cardiac Output in Cardiac Surgery: A Prospective Comparison with Thermodilution, Echocardiography, and Magnetic Resonance Techniques

Objective: The aim of this study was to compare the accuracy of cardiac output (CO) measurements of noninvasive continuous arterial pressure waveform analysis, thermodilution technique and echocardiography with magnetic resonance (MRI) imaging. Methods: Eleven patients who underwent coronary bypass surgery under cardiopulmonary bypass were prospectively enrolled in this study in 2008. Repeated arterial pressure based, thermodilution, echocardiography, and MRI cardiac output measurements were performed at the postoperative 24th hour. Results: Mean CO values were 5.58 +/- 0.98, 5.97 +/- 0.8, 5.31 +/- 0.52, and 5.32 +/- 0.92 measured with MRI, echocardiography, arterial pressure waveform analysis, and thermodilution techniques, respectively. Bland-Altman analysis showed good overall agreement between the MRI vs arterial waveform analysis and MRI vs thermodilution; values for bias +/- SD were -0.27 +/- 1.06 (95% confidence interval [CI] [-2.3 to 1.8]; P = .42) and -0.26 +/- 0.89 (95% CI [-2.0 to 1.5]; P = .34), respectively. Poor agreement was defined between MRI and echocardiography: bias +/- SD, 0.39 +/- 1.28 (95% CI [-2.1 to 2.9]; P = .34). Conclusions: Arterial pressure - based and thermodilution CO measurement systems yielded results comparable to those obtained with cardiac MRI assessment after cardiac surgery. Arterial pressure wave- form analysis systems for CO measurement may be feasible, noninvasive methods for use in cardiac surgery.