Measurement of cardiac output in pregnancy by thermodilution and impedance techniques.

To assess the value of impedance cardiography in pregnancy, simultaneous measurements of cardiac output were made with impedance and thermodilution techniques in 10 patients who required pulmonary artery catheterization. The methods correlated poorly (r = 0.17). The discrepancy between methods was particularly pronounced in hypertensive patients. Impedance cardiography does not measure cardiac output accurately in hypertensive pregnant women.