Impedance cardiography (electrical velocimetry) and transthoracic echocardiography for non-invasive cardiac output monitoring in pediatric intensive care patients: a prospective single-center observational study

Introduction: Electrical velocimetry (EV) is a type of impedance cardiography, and is a non-invasive and continuously applicable method of cardiac output monitoring. Transthoracic echocardiography (TTE) is non-invasive but discontinuous. Methods: We compared EV with TTE in pediatric intensive care patients in a prospective single-center observational study. Simultaneous, coupled, left ventricular stroke volume measurements were performed by EV using an Aesculon (R) monitor and TTE (either via trans-aortic valve flow velocity time integral [EVVTI], or via M-mode [EVMM]). H-0: bias was less than 10% and the mean percentage error (MPE) was less than 30% in Bland-Altman analysis between EV and TTE. If appropriate, data were logarithmically transformed prior to Bland-Altman analysis. Results: A total of 72 patients (age: 2 days to 17 years; weight: 0.8 to 86 kg) were analyzed. Patients were divided into subgroups: organ transplantation (OTX, n = 28), sepsis or organ failure (SEPSIS, n = 16), neurological patients (NEURO, n = 9), and preterm infants (PREM, n = 26); Bias/MPE for EVVTI was 7.81%/26.16%. In the EVVTI subgroup analysis for OTX, NEURO, and SEPSIS, bias and MPE were within the limits of H-0, whereas the PREM subgroup had a bias/MPE of 39.00%/46.27%. Bias/MPE for EVMM was 8.07%/37.26% where the OTX and NEURO subgroups were within the range of H-0, but the PREM and SEPSIS subgroups were outside the range. Mechanical ventilation, non-invasive continuous positive airway pressure ventilation, body weight, and secondary abdominal closure were factors that significantly affected comparison of the methods. Conclusions: This study shows that EV is comparable with aortic flow-based TTE for pediatric patients.