In vitro validation of a thermodilution right ventricular ejection fraction method.

A thermodilution catheter and computer system has been developed to measure right ventricular ejection fraction and volumes. To evaluate the performance of this method, the thermodilution system was evaluated in an in vitro pulsatile flow model. Thermodilution measurements of ejection fraction (EF), cardiac output (CO), stroke volume (SV), end-diastolic volume (EDV), and end-systolic volume (ESV) were compared with known values in a pulsatile flow bench. Thermodilution EF measurements correlated very well with the pulsatile flow model (r2 = 0.95, m [slope] = 0.85, SEE = 4.0 EFU). Thermodilution CO and SV were highly predictive of actual pulsatile flow (r2 = 0.99, m = 0.99, SEE = 187 ml/min and r2 = 0.98, m = 0.96, SEE = 2.5 ml, respectively). Thermodilution end-diastolic and end-systolic volume measurements resulted in low mean eror, -1.8% and 0.6%, respectively. The standard deviations of the error for EDV and ESV were 11.0% and 16.4%. The thermodilution measurements were repeatable, with CO, SV, and EF coefficients of variation of 3.2%, 3.3%, and 4.7%, respectively. EDV and ESV were slightly more variable, with coefficients of variation of 5.5% and 7.2%, respectively.