Cardiac output by PulseCO™ is not interchangeable with thermodilution in patients undergoing OPCAB

Purpose: To investigate the reliability of cardiac output assessed by arterial pressure waveform (PulseCO™) in comparison with bolus thermodilution measurements in patients undergoing off-pump coronary artery bypass grafting (OPCAB). Methods: 23 patients who underwent OPCAB were enrolled in this study. After premedication with oral diazepam 10 mg, anesthesia was induced with midazolam, fentanyl and vecuronium. After induction, radial artery and pulmonary artery catheters were inserted. Cardiac output was measured simultaneously by the PulseCO™ and the bolus thermodilution method using the Vigilance™ monitor: 1) after sternotomy, 2) after opening the mediastinum, and 3) at the end of surgery. The PulseCO™ was calibrated initially with cardiac output determined by the thermodilution method after induction of anesthesia. Results: The correlation coefficients between the two techniques at the three measurement periods were: 1) R² = 0.49, 2) R² = 0.52, 3) R² = 0.55. The limits of agreement (bias ± 2 SD of bias) were: 1) 0.71 ± 2.66, 2) 0.30 ± 1.97, 3) 0.76 ± 3.85 L·min^-1. Conclusions: Cardiac output by PulseCO™ is not interchangeable with cardiac output measured by thermodilution in patients undergoing OPCAB.