TRANSESOPHAGEAL ECHOCARDIOGRAPHIC MEASUREMENTS OF CARDIAC-OUTPUT IN CARDIAC SURGICAL PATIENTS

Transesophageal echocardiography is becoming increasingly popular as a method of intraoperative monitoring because it can be performed conti nuously, does not transgress the sterile operative field, and provides data with regard to valve function, ventricular volumes, and contract ility. Recently it was suggested that it can be used to measure cardia c output; however, controversy remains regarding its accuracy. Cardiac output was measured simultaneously by transesophageal echocardiograph y (using a 5-MHz pulse-wave Doppler, single-plane viewing probe) and b y the thermodilution method in 21 patients undergoing open heart opera tions. The cardiac outputs measured by thermodilution correlated poorl y (r = 0.45) with the transesophageal values derived from the left ven tricular cross-sectional area, and the mean difference was 0.47 +/- 2. 17 (standard deviation)L.min(-1), giving limits of agreement of from - 3.87 to +4.81 L.min(-1). Cardiac outputs measured by thermodilution co rrelated well (r = 0.95) with transesophageal Doppler values derived f rom pulmonary artery flow velocity, with a mean difference of 0.12 +/- 0.45 L.min(-1) and narrow limits of agreement of from -0.78 to +1.02 L.min(-1). Based on our findings, transesophageal Doppler echocardiogr aphic determination of cardiac output using pulmonary artery now measu rements can provide accurate hemodynamic data in patients undergoing c ardiac operations.