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

This prospective observational study aimed to assess the agreement of cardiac output measurements obtained with transthoracic echocardiography (COECHO) and electrical velocimetry (COEV) and the impact of relevant variables on COEV accuracy in preterm infants during the transitional period. Simultaneous measurements of COEV and COECHO 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 COEV-COECHO 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 COEV 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 COEV 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.