Measuring cardiac output during dobutamine infusion after off-pump coronary artery bypass: comparison of transesophageal echo-Doppler and thermodilution.

AIM To compare transesophageal echo-Doppler with thermodilution method for measuring cardiac output during dobutamine infusion after off-pump coronary artery bypass. METHOD Using transesophageal echo-Doppler and thermodilution methods, we measured cardiac output in 30 patients after off-pump coronary artery bypass, immediately before and 5, 15, and 30 min after the introduction of continuous dobutamine infusion (3 microg/kg/min). Paired t-test and Bland-Altman analysis were used to compare the results obtained by two methods in this prospective study. RESULTS Significant increase in cardiac output during dobutamine infusion was detected by both thermodilution (from 3.9 +/- 1.0 to 4.6 +/- 1.1 L/min; p < 0.001) and transesophageal echo-Doppler (from 3.8 +/- 1.2 to 4.8 +/- 1.4 L/min; p < 0.001). Initial measurement results of thermodilution and transesophageal echo-Doppler techniques showed clinically acceptable agreement, with a mean difference of only + 0.09 L/min (95% confidence interval (CI), 0.42 to + 0.61). Subsequently repeated measurements after 5, 15, and 30 min showed almost the same agreement between the methods. The highest mean difference between the initial and repeated measurements was found at 5 min after the introduction of dobutamine infusion (-0.29 L/min, 95% CI, -1.06 to + 0.48). CONCLUSION Transesophageal echo-Doppler and thermodilution can be interchangeable as methods for measuring cardiac output after off-pump coronary artery bypass.