Right Ventricular Volumes by Thermodilution in the Adult Respiratory Distress Syndrome: A Comparative Study Using TWo-Dimensional Echocardiography as a Reference Method

Abstract

Measurements of right ventricular ejection fraction and volumes were obtained at bedside by the thermodilution method performed with a fast-response balloon-tipped thermistor in a group of 18 patients undergoing respiratory therapy for the adult respiratory distress syndrome (ARDS). These measurements were compared with right ventricular dimensions simultaneously obtained with two-dimensional echocardiography. A significant correlation was found between right ventricular ejection fraction by thermodilution and two-dimensional echocardiographic fractional area contraction (r = 0.74; p less than 0.001), between right ventricular end-diastolic volume by thermodilution and two-dimensional echocardiographic end-diastolic area (r = 0.70; p less than 0.001), and between right ventricular end-systolic volume by thermodilution and two-dimensional echocardiographic end-systolic area (r = 0.78; p less than 0.001). Right ventricular end-diastolic pressure, a commonly used index of right ventricular preload, did not correlate with two-dimensional echocardiographic end-diastolic area. In conclusion, the thermodilution method allowed reliable measurements of right ventricular ejection fraction and volumes at bedside in critically ill patients. Appraisal of right ventricular end-diastolic volume by this method appeared to be a better predictor of right ventricular preload than were the measurements of pressure.