Accuracy of non-invasive measurement of cardiac output using electrical cardiometry in preterm infants during the transitional period: A comparison with transthoracic Doppler echocardiography

Abstract

This prospective observational study aimed to assess the agreement of cardiac output measurements obtained with transthoracic echocardiography (CO_ECHO) and electrical velocimetry (CO_EV) and the impact of relevant variables on CO_EV accuracy in preterm infants during the transitional period. Simultaneous measurements of CO_EV and CO_ECHO were performed in preterm infants < 32 weeks' gestation and/or < 1500 g during the first 72 h of life. Bland-Altman analysis was performed and bias and mean percentage error (MPE) were calculated. The impact of a hemodynamically significant duct (hsPDA), ongoing cardiovascular drugs and ventilatory support was also assessed using a generalized least squares random-effects model. A total of 170 pairs of CO_EV-CO_ECHO measurements were obtained from 65 preterm neonates. Mean bias was 9.7 ml/kg/min (95%CI 1.3-18.2) on day 1, 8.3 ml/kg/min (95%CI 0.3-16.4) on day 2, and 10.6 ml/kg/min (95%CI 4.5-16.6) on day 3 of life. The corresponding MPE was 7.2% (95%CI 4.8-10.6%), 7.5% (95%CI 4.7-12.8%) and 7.0% (95%CI 5.4-9.1%), respectively. A CO_EV overestimation was observed in the presence of hsPDA (mean bias = 17.0 ml/kg/min, 95%CI 7.1-30.8, p = 0.003) and during dobutamine treatment (mean bias = 12.5 ml/kg/min, 95%CI 1.5-22.4, p = 0.018). No significant differences were observed according to dopamine administration and respiratory support modality.

Conclusion: Although a slight overestimation may occur during inotropic treatments and in the presence of a hsPDA, this study shows an acceptable accuracy and precision of CO_EV in preterm infants during postnatal transition, thus supporting the role for EV monitoring in this critical phase.

What is known: • Electrical velocimetry allows a continuous and non-invasive monitoring of cardiac output (CO) in the neonatal population. • Available data comparing the accuracy of electrical velocimetry against transthoracic echocardiography for CO assessment in preterm infants are still controversial.

What is new: • The present data report a satisfactory accuracy of electrical velocimetry for CO assessment, with low bias and mean percentage error when compared to echocardiographic CO measurements. • Inotropic treatment with dobutamine and a hemodynamically significant duct may be associated with a slight but significant overestimation of CO measurements by electrical velocimetry.

Keywords: Accuracy; Echocardiography; Electrical velocimetry; Non-invasive cardiac output monitoring; Patent Ductus arteriosus; Preterm infants.

Fig. 1

Bland–Altman plot of cardiac output measured with electrical velocimetry (CO_EV) versus echocardiography (CO_ECHO) on day 1, 2 and 3 of life according to the presence of a haemodynamically significant patent ductus arteriosus (PDA) (panel A) and to dobutamine administration (panel B). Red-dashed lines indicate the upper and lower limit of agreement (mean CO_EV-CO_ECHO difference ± 1.96 * standard deviation [SD]). Short-dashed lines indicate the 95% confidence interval for the mean difference