Comparison of cardiac output measures by transpulmonary thermodilution, pulse contour analysis, and pulmonary artery thermodilution during off-pump coronary artery bypass surgery: a subgroup analysis of the cardiovascular anaesthesia registry at a single tertiary centre.

Cardiac output measurement has a long history in haemodynamic management and many devices are now available with varying levels of accuracy. The purpose of the study was to compare the agreement and trending abilities of cardiac output, as measured by transpulmonary thermodilution and calibrated pulse contour analysis, using the VolumeView™ system, continuous thermodilution via a pulmonary artery catheter, and uncalibrated pulse contour analysis, using FloTrac™ with pulmonary artery bolus thermodilution. Twenty patients undergoing off-pump coronary artery bypass surgery using a pulmonary artery catheter and the VolumeView™ and FloTrac™ systems were included in this subgroup analysis of the cardiovascular anaesthesia registry at a single tertiary centre. During surgery, cardiac output was assessed after the induction of anaesthesia, after sternotomy, during the harvesting of grafts, during revascularization of the anterior and posterior/lateral wall, after protamine infusion, and after sternal fixation. In total, 145 sets of measurements were evaluated using Bland-Altman with % error calculation, correlation, concordance, and polar plot analyses. The percentage error (bias, limits of agreement) was 12.6 % (-0.12, -0.64 to 0.41 L/min), 26.7 % (-0.38, -1.50 to 0.74 L/min), 29.3 % (-0.08, -1.32 to 1.15 L/min), and 33.8 % (-0.05, -1.47 to 1.37 L/min) for transpulmonary thermodilution, pulmonary artery continuous thermodilution, calibrated, and uncalibrated pulse contour analysis, respectively, compared with pulmonary artery bolus thermodilution. All pairs of measurements showed significant correlations (p < 0.001), whereas only transpulmonary thermodilution revealed trending ability (concordance rate of 95.1 %, angular bias of 1.33°, and radial limits of agreement of 28.71°) compared with pulmonary artery bolus thermodilution. Transpulmonary thermodilution using the VolumeView™ system provides reliable data on cardiac output measurement and tracking the changes thereof when compared with pulmonary artery bolus thermodilution in patients with preserved cardiac function during off-pump coronary artery bypass surgery. Trial registration NCT01713192 (ClinicalTrials.gov).