Modelflow: a new method for noninvasive assessment of cardiac output in pregnant women.

Abstract

Estimation of cardiac output by continuous finger arterial pressure waveform analysis with Modelflow is a noninvasive technique for beat-to-beat hemodynamic assessment. The purpose of this study was to compare this method in pregnant women with the more commonly used Doppler echocardiography. In 16 primigravid women, stroke volume was measured serially in first, second, and third trimester and after pregnancy by the Modelflow method and by Doppler echocardiography. Aortic diameter and compliance were assessed serially by echocardiography and pulse wave velocity measurements. Aortic compliance was increased significantly in pregnancy compared with nonpregnant values, but aortic diameter did not change. After adjustment for pregnancy-related changes in pulse wave velocity, blood pressure, and heart rate, Modelflow stroke volume measurements gave comparable results to Doppler echocardiography during and after pregnancy. The observed variation was similar to reported comparisons of Doppler echocardiography with thermodilution. After adjustment for pregnancy the Modelflow method is a useful research tool for assessment of stroke volume in pregnant women and offers the advantage of continuous measurement and convenience of application.