A validation study of stroke volume measurement by means of electrical impedance tomography

ECG-gated electrical impedance tomography (EIT) has been developed to monitor blood volume changes. The aim of this study was to compare stroke volume measurements by EIT with established methods of thermodilution and magnetic resonance imaging (MRI). After right cardiac catheterization, EIT measurements were performed in 26 patients. Regression analysis was used to analyze the relation between the EIT results and stroke volume. From the regression line an equation was derived to estimate stroke volume (in ml) by EIT. In a group of eleven healthy subjects this equation was validated to MRI. A strong correlation was found between EIT and stroke volume measured by the thermodilution method (r=0.86). The reproducibility coefficient for EIT measurements was 0.98. The average standard deviation between stroke volume measured by EIT and MRI is 5.4 ml, the mean difference between both methods is 0.7 ml and the coefficient of variation is 8.4%. We conclude that EIT is a valid and reproducible method for the assessment of stroke volume in healthy controls and cardiological patients.