Cardiac output measurements with electrical velocimetry in patients undergoing CABG surgery: a comparison with intermittent thermodilution.

BACKGROUND AND OBJECTIVE

The purpose was to study the agreement between cardiac output measurements with electrical velocimetry vs. intermittent thermodilution before and after coronary artery bypass graft surgery.

METHODS

Cardiac output was measured simultaneously with electrical velocimetry and intermittent thermodilution before and immediately after coronary artery bypass graft surgery, and in the intensive care unit. Measurements were performed in three different body positions. The results were analysed according to Bland and Altman.

RESULTS

The mean bias of all 150 paired measurements in 16 patients was 0.21 +/- 0.78 L min(-1), and the mean error was 40%. Before skin incision the mean bias was 0.04 +/- 0.41 L min(-1), and the mean error was 25%. After skin closure the mean bias was 0.57 +/- 0.92 L min(-1), and the mean error was 42%. In the intensive care unit the mean bias was 0.26 +/- 0.68 L min(-1), and the mean error was 32%.

CONCLUSIONS

The agreement between cardiac output measurements with electrical velocimetry and intermittent thermodilution was clinically acceptable only before skin incision in coronary artery bypass graft surgery. The mean error was unacceptably high immediately after skin closure and was at a borderline level in the intensive care unit. Thus, the overall accuracy of cardiac output measurements with the electrical velocimetry technique during coronary artery bypass graft surgery is not clinically unacceptable.