Comparison of bioreactance and echocardiographic non-invasive cardiac output monitoring and myocardial function assessment in primagravida women.

Background.: Non-invasive cardiac output monitoring (NICOM) using bioreactance (BRT) in pregnancy is gaining interest but lacks validation. We compared simultaneous cardiac output (CO) measurements obtained using the NICOM ® (BRT-CO) and echocardiography (echo-CO), and assessed the relationship between maternal characteristics and myocardial performance.

Methods.: Paired stroke volume (SV) and CO readings were obtained using NICOM ® and echocardiography, in a group of healthy nulliparous women throughout a 15 min period. Agreement between NICOM ® and echocardiography was assessed using Bland-Altman analysis and the intraclass correlation coefficient (ICC). Left ventricular (LV) function was assessed using systolic strain and tissue Doppler velocities (S', E', and A' waves).

Results.: Thirty-five women with a median [interquartile range] age, weight, and gestation of 29 [26-34] yr, 71 [64-79] kg, and 28 [21-29] weeks, respectively, were enrolled. There was good agreement between NICOM ® -measured and echocardiographically measured SV [mean bias 6 ml (limits of agreement -18 to 29); ICC 0.8 (95% confidence interval 0.6-0.9), P <0.001] and CO [mean bias 0.2 litres (limits of agreement -1.3-1.7); ICC 0.8 (95% confidence interval 0.7-0.9), P <0.001; mean percentage error ±26%; coefficient of error (precision)=3.4%]. The mean ( sd ) LV S' was 9.7 (2.3) cm s -1 . The mean ( sd ) LV strain was -18.6 (2.6)%. There was a negative relationship between BMI and LV diastolic function measured using the E':A' ratio ( r  = -0.51, P <0.01).

Conclusions.: Stroke volume and CO measurements obtained using NICOM ® were comparable to those obtained using echocardiography, with acceptable limits of agreement. Increased maternal BMI negatively impacts LV diastolic function measured using tissue Doppler imaging.