A comparison of transoesophageal echocardiographic Doppler across the aortic valve and the thermodilution technique for estimating cardiac output

This study was undertaken in order to elucidate the differences between var ious planes of measurement and Doppler techniques (pulsed- vs. continuous-w ave Doppler) across the aortic valve to estimate cardiac output. In 45 coro nary artery bypass patients, cardiac output was measured each time using fo ur different Doppler techniques (transverse and longitudinal plane, pulsed- and continuous-wave Doppler) and compared with the thermodilution techniqu e. Measurements were performed after induction of anaesthesia and shortly a fter arrival in the intensive care unit. Optimal imaging was obtained in 91 % of the patients, ill whom a total of 82 measurements of cardiac output we re performed. The respective mean (SD) areas of the aortic valve were 3.77 (0.71) cm(2) ill the transverse plane and 3.86 (0.89) cm(2) in the longitud inal plane. A correlation of 0.87 was found between pulsed-wave Doppler car diac output and the thermodilution technique ill either transverse or longi tudinal plane. Correlation coefficients of 0.82 and 0.84 were found between thermodilution cardiac output and transverse and longitudinal continuous-w ave Doppler cardiac output, respectively. Although thermodilution cardiac o utput is a widely accepted clinical standard, transoesophageal Doppler echo cardiography across the aortic valve offers adequate estimations of cardiac output. ill particular, pulsed-wave Doppler cardiac output in both the tra nsverse and longitudinal plane provides useful data.