Comparison of Cardiac Output Measurement by Electrical Velocimetry with Echocardiography in Extremely Low Birth Weight Neonates

Abstract

Introduction: Electrical velocimetry (EV) offers a noninvasive tool for continuous cardiac output (CO) measurements which might facilitate hemodynamic monitoring and targeted therapy in low birth neonates, in whom other methods of CO measurement are not practicably feasible. Methods: This prospective observational study compared simultaneous cardiac output measurements by electrical velocimetry (CO_EV) with transthoracic echocardiography (CO_TTE) in extremely low birth weight (ELBW) neonates in the neonatal intensive care unit (NICU). Echocardiography was performed by 1 single examiner. Data were analyzed by Bland-Altman analysis and independent-samples analysis of variance. A mean percentage error (MPE) of <30% and limits of agreement (LOA) up to ±30% were considered clinically acceptable. Results: Thirty-eight ELBW neonates were studied and yielded 85 pairs of CO_EV and CO_TTE measurements. Bland-Altman analysis showed an overall bias (the mean difference) and LOA of −126 and −305 to +52 mL min⁻¹, respectively, and an MPE of 66%. Patients with patent ductus arteriosus had a higher bias with LOA and MPE of −166.8, −370.7 to +37 mL min⁻¹, and 69%, respectively. The overall true precision was 58%. Conclusion: This study showed high bias and lack of agreement between EV and TTE for measurement of CO in ELBW infants in NICU, limiting applicability of EV to monitor absolute values.