Stroke volume and cardiac output evaluation by electrical cardiometry: Accuracy and reference nomograms in hemodynamically stable preterm neonates

Abstract

Objective:To investigate the accuracy of electrical cardiometry (EC) to measure stroke volume (SV) and cardiac output (CO) and to provide gestational age (GA) and birth weight (BW)-based reference data for SV and CO in hemodynamically stable preterm neonates.Study Design:Prospective observational blinded study. Paired measurements of SV and CO on stable preterm infants without any hemodynamic compromise were carried out using EC (SV EC) and echocardiography (SV ECHO).Results:Seventy-nine preterm neonates (mean GA: 31±3.2 weeks) were enrolled. A good correlation was found for SV (r=0.743; P<0.0001) and CO (r=0.7; P<0.0001) measured by EC and echocardiography. These correlations remained significant after adjusting for GA, patent ductus arteriosus and type of respiratory support (SV: St.β=0.48, P<0.0001 and CO: St.β=0.69, P<0.0001). Mean biases (and variabilities) were-1.1 (from 0.7 to-2.9) ml and-0.21 (from 0.15 to-0.55) l min-1 for SV and CO, respectively. Local regression shows a tendency for EC to overestimate SV and CO especially at higher values (at about >2 ml and >0.4 l min-1, respectively). Coefficient of variation of SV was 48.9% and 52%, for EC and echocardiography. SV and CO rose with increasing GA and BW following an exponential equation (R 2 >0.8).Conclusion:Measuring SV and CO with EC in hemodynamically stable preterm infants shows good correlation and variability similar to that of echocardiography. A trend to overestimation exists at highest values, but it is unlikely to be clinically significant. Reference GA and BW-based nomograms for SV and CO are provided.