Comparison between Modelflow® and echocardiography in the determination of cardiac output during and following pregnancy at rest and during exercise

During pregnancy, assessment of cardiac output (Q), a fundamental measure of cardiovascular function, provides important insight into maternal adaptation. However, methods for dynamic Q measurement require validation. The purpose of this study was to estimate the agreement of Q measured by echocardiography and Modelflow® at rest and during submaximal exercise in non-pregnant (n = 18), pregnant (n = 15, 22-26 weeks gestation) and postpartum women (n = 12, 12-16 weeks post-delivery). Simultaneous measurements of ˙ derived from echocardiography [criterion] and Modelflow® were obtained at rest and during low-moderate intensity (25% and 50% peak power output) cycling exercise and compared using Bland-Altman analysis and limits of agreement. Agreement between echocardiography and Modelflow® was poor in non-pregnant, pregnant and postpartum women at rest (mean difference ± SD:-1.1 ± 3.4;-1.2 ± 2.9;-1.9 ± 3.2 L. min-1), and this remained evident during exercise. The Modelflow® method is not recommended for Q determination in research involving young, healthy non-pregnant and pregnant women at rest or during dynamic challenge. Previously published Q data from studies utilising this method should be interpreted with caution.