Cardiac Output Monitoring: Comparison of a New Arterial Pressure Waveform Analysis to the Bolus Thermodilution Technique in Patients Undergoing Off-Pump Coronary Artery Bypass Surgery

Objective: To analyze the clinical agreement between the conventional intermittent bolus thermodilution (TD) technique and a new arterial pressure waveform analysis (APCO) technique (FloTrac; Edward Lifesciences, Irvine, CA) for cardiac output (CO) estimation.

Design: Prospective observational clinical study.

Setting: Cardiac surgery operating room of a tertiary care cardiac center.

Participants: Twelve patients undergoing elective off-pump coronary artery bypass (OPCAB) surgery.

Measurements and Main Results: CO was determined by 2 different methods: TD and APCO at 8 time points (preinduction, postinduction, poststernotomy, left internal mammary artery to left anterior descending artery anastomosis, left [obtuse marginal/diagonal] anastomosis, right [right coronary/posterior descending coronary artery] anastomosis, postprotamine administration, and poststernal closure) in 12 patients undergoing elective OPCAB surgery. The mean bias and limits of agreement (2 standard deviations) expressed in liters per minute at respective points of measurement were −0.54 ± 1.12, −0.37 ± 1.0, −0.42 ± 1.50, −0.25 ± 1.18, −0.31 + 1.28, ±0.41 ± 1.0, 0.06 ± 1.50, and 0.09 ± 1.40.

Conclusion: Good agreement was found between the CO values obtained by the APCO and TD techniques throughout the intraoperative period including the period of coronary artery graft surgery.

Key words: cardiac output, thermodilution, pulse-contour analysis, systemic vascular resistance