Comparison of continuous, stat, and intermittent cardiac output measurements in patients undergoing minimally invasive direct coronary artery bypass surgery

OBJECTIVE: To compare intermittent cardiac output (ICO) with continuous cardiac output (CCO) and stat cardiac output (SCO) measurements in patients undergoing minimally invasive direct coronary artery bypass (MIDCAB) surgery. DESIGN: Prospective, clinical study. SETTING: Single, tertiary referral center. PARTICIPANTS: Twenty adult patients undergoing off-pump MIDCAB surgery from January through June 2000. INTERVENTIONS: Each patient had a 7.5F 5-lumen pulmonary artery thermodilution catheter (CCO catheter, Baxter Healthcare Corporation, Irvine, CA) inserted for measurement of cardiac output (CO). ICO, CCO, and SCO were compared at 10 predefined time points. RESULTS: A total of 400 data pairs for CO were obtained. ICO values ranged from 1.8 to 8.4 L/min; CCO, 1.9 to 7.5 L/min; and SCO, 2.25 to 6.35 L/min. Correlation between ICO and CCO was significant (correlation coefficient, r = 0.78, p < 0.001), accompanied by a bias of -0.095 L/min and precision of 0.729 L/min. Similarly, the correlation between ICO and SCO was significant (r = 0.79, p < 0.001), accompanied by good accuracy (bias, 0.084 L/min) and precision (0.843 L/min). There were statistically significant decreases in mean arterial pressure, CO, cardiac index, stroke volume, stroke volume index, and left and right ventricular stroke work indices during anastomosis of the left internal mammary artery to left anterior descending artery. These parameters returned to baseline preinduction values 1 minute after completion of the anastomosis. CONCLUSION: Excellent correlation, accuracy, and precision were found among the 3 methods of measuring CO in patients undergoing MIDCAB surgery. Further studies are needed to assess their accuracy in multivessel off-pump coronary artery bypass graft surgery and in patients with poor left ventricular function.