Measurement of cardiac output after cardiac surgery by a new transesophageal Doppler device

Abstract

Objectives: Assessment of hemodynamics by transesophageal Doppler devices (TDD) may be a less invasive alternative to the pulmonary artery catheter. In contrast to the TDD evaluated so far, a new monitor (HemoSonic100) measures both blood flow velocity and the diameter of the descending aorta. The aim of this study was to assess the accuracy of the cardiac output/index (CO/CI) measured by this device compared with the CO/CI measured by thermodilution.

Design: Prospective nonrandomized study.

Setting: Community hospital; university-based statistician.

Participants: Twenty-two patients.

Interventions: Elective coronary artery bypass grafting and/or valve replacement/repair.

Measurements and main results: After routine cardiac surgery, CO/CI was determined in the intensive care unit by iced-water bolus (IWB), continuous cardiac index (CCI) assessment, and the TDD. Matched measurements were made with each patient at intervals of 30 minutes. Six percent of sets were incomplete because of failed signal detection by the TDD. Bland-Altman analysis revealed a mean bias of 0.23 L/min/m(2) for TDD and IWB. Mean bias for CCI and IWB was 0.11 L/min/m(2). The correlation between TDD and IWB (r(2) = 0.09) for cardiac index was found to be inferior to the correlation between CCI and IWB (r(2) = 0.65). Trend analysis between sequential measurements (T1-4: dTDD, dCCI, dIWB) showed a lower correlation between dTDD and dIWB (r(2) = 0.1) compared with the correlation between dCCI and dIWB (r(2) = 0.44).

Conclusion: The transesophageal Doppler device (HemoSonic100) cannot be recommended as a sole method for monitoring cardiac output in patients after cardiac surgery.