Arterial pulse waveform analysis has been proposed for cardiac output (CO) determination and monitoring without calibration or thermodilution (FloTrac™/Vigileo™; Edwards Lifesciences, Irvine, CA, USA). The accuracy and clinical applicability of this technology has not been fully evaluated. We designed this prospective study to compare the accuracy of the FloTrac™ system (COFT) vs. pulmonary artery catheter standard bolus thermodilution (COPAC) in patients undergoing coronary artery bypass grafting.

We studied 11 patients referred for coronary artery bypass grafting. COFT and COPAC were determined at six time points in the operating room including before and 5 min after volume expansion (500 mL 6% hetastarch). Measurements were performed on arrival in the intensive care unit and every 4 h afterwards. Bland–Altman analysis was used to assess the agreement between COFT and COPAC.

COPAC ranged from 2.0 to 7.6 L min−1 and COFT ranged from 1.9 to 8.2 L min−1. There was a significant relationship between COPAC and COFT (r = 0.662; P < 0.001). Agreement between COPAC and COFT was −0.26 ± 0.87 L min−1. Volume expansion induced a significant increase in both COPAC and COFT (from 3.4 ± 0.8 to 4.4 ± 1.0 L min−1; P < 0.001 and from 3.9 ± 1.2 to 5.0 ± 1.1 L min−1; P < 0.001, respectively) and there was a significant relationship between percent change in COPAC and COFT following volume expansion (r = 0.722; P = 0.01).

We found clinically acceptable agreement between COFT and COPAC in this setting. This new device has potential clinical applications.