Key result
Thoracic bioreactance reliably matches echocardiography for pregnancy cardiac output with ~0.13 L/min mean bias.
Why the study?
There is growing interest in the use of non-invasive cardiac output monitoring to guide antihypertensive and fluid therapies in obstetrics, but validation in pregnancy is needed.
Does thoracic bioreactance (NICOM) accurately measure cardiac output compared to transthoracic echocardiography in pregnant women?
Observational (n=166)
Does thoracic bioreactance (NICOM) accurately measure cardiac output compared to transthoracic echocardiography in pregnant women?
Thoracic bioreactance (NICOM) demonstrates good agreement with echocardiography and can be used as a non-invasive method to measure cardiac function in pregnant women.
May support NICOM for non-invasive cardiac output monitoring in pregnancy; leaves open need for outcome-validated prospective trials.
Summary Maternal cardiac dysfunction is associated with pre‐eclampsia, fetal growth restriction and haemodynamic instability during obstetric anaesthesia. There is growing interest in the use of non‐invasive cardiac output monitoring to guide antihypertensive and fluid therapies in obstetrics. The aim of this study was to validate thoracic bioreactance using the NICOM® instrument against transthoracic echocardiography in pregnant women, and to assess the effects of maternal characteristics on the absolute difference of stroke volume, cardiac output and heart rate. We performed a prospective study involving women with singleton pregnancies in each trimester. We recruited 56 women who were between 11 and 14 weeks gestation, 57 between 20 and 23 weeks, and 53 between 35 and 37 weeks. Cardiac output was assessed repeatedly and simultaneously over 5 min in the left lateral position with NICOM and echocardiography. The performance of NICOM was assessed by calculating bias, 95% limits of agreement and mean percentage difference relative to echocardiography. Multivariate regression analysis evaluated the effect of maternal characteristics on the absolute difference between echocardiography and NICOM. The mean percentage difference of cardiac output measurements between the two methods was ±17%, with mean bias of −0.13 l.min −1 and limits of agreement of −1.1 to 0.84; stroke volume measurements had a mean percentage difference of ±15%, with a mean bias of −0.8 ml (−10.9 to 12.6); and heart rate measurements had a mean percentage difference of ±6%, with a mean bias of −2.4 beats.min −1 (−6.9 to 2.0). Similar results were found when the analyses were confined to each individual trimester. The absolute difference between NICOM and echocardiography was not affected by maternal age, weight, height, race, systolic or diastolic blood pressure. In conclusion, NICOM demonstrated good agreement with echocardiography, and can be used in pregnancy for the measurement of cardiac function.
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Ling et al. (2020) conducted an observational in Pregnancy (n=166). Thoracic bioreactance (NICOM) vs. Transthoracic echocardiography was evaluated on Cardiac output measurement agreement (mean bias -0.13 l.min-1, 95% CI -1.1 to 0.84). Thoracic bioreactance using NICOM demonstrated good agreement with echocardiography for measuring cardiac output in pregnancy (mean bias -0.13 l/min; 95% limits of agreement -1.1 to 0.84).
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