INTRAOPERATIVE DETERMINATION OF CARDIAC-OUTPUT USING MULTIPLANE TRANSESOPHAGEAL ECHOCARDIOGRAPHY - A COMPARISON TO THERMODILUTION

Background: Limitations in the imaging views that can be obtained with transesophageal echocardiography (TEE) have hindered development of a widely adopted Doppler method for cardiac output (CO) monitoring. The authors evaluated a CO technique that combines steerable continuous-w ave Doppler with the imaging capabilities of two-dimensional multiplan e TEE. Methods: From the transverse plane transgastric, short-axis vie w of the left ventricle, the imaging array was rotated to view the lef t ventricular outflow tract (LVOT) and ascending aorta. Steerable cont inuous-wave Doppler was subsequently used to measure aortic blood flow velocities, Aortic valve area was determined using a triangular orifi ce model. Matched thermodilution and Doppler CO measurements were obta ined serially during surgery. Results: The left ventricular outflow tr act was imaged in 32 of 33 patients (97%). Data analysis reveal a mean difference between techniques of - 0.01 l/min, and a standard deviati on of the differences of 0.56 l/min. Multiple regression showed a corr elation of r = 0.98 between intrasubject changes in CO. Multiplane TEE correctly tracked the direction of 37 of 38 serial changes in thermod ilution CO but with a modest 14% underestimation of the magnitude of t hese changes. Conclusions: These results indicate that multiplane TEE can provide an alternative method for the intraoperative measurement o f CO. The ability of the rotatable imaging array to align with the lef t ventricular outflow tract and the need for only minimal adjustments in probe position advance the utility of intraoperative TEE.