Validation of thoracic impedance cardiography by echocardiography in healthy late pregnancy.

Jordan Pr Mcintyre,Gina M Quill,Alistair W Stewart,Kevin M Ellyett,Robert N Doughty,Edwin A Mitchell,John Md Thompson,Peter R Stone

doi:10.1186/s12884-015-0504-5

Jordan Pr Mcintyre, Gina M Quill + Show 6 more

Open Access

https://doi.org/10.1186/s12884-015-0504-5

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Abstract

BackgroundAssessment of stroke volume (SV) is often necessary in clinical and research settings. The clinically established method for SV assessment in pregnancy is echocardiography, but given its limitations, it is not always an appropriate measurement tool. Thoracic impedance cardiography (ICG) allows continuous, non-invasive SV assessment. However, SV determination relies on assumptions regarding the thoracic shape that may mean the algorithm is not valid in pregnancy. The available data regarding the validity of ICG against an established reference standard using modern SV algorithms are both limited and conflicting. We aimed to test the validity of ICG in a clinically realistic setting in late pregnancy using echocardiography.MethodsTwenty-nine women in late pregnancy underwent standard echocardiography assessments with simultaneous ICG measurement. Agreement between devices was tested using Bland-Altman analysis.ResultsBland-Altman analysis of the relationship between ICG and echocardiography demonstrated that the 95% limits of agreement exceeded acceptable or expected ranges. Measures of maternal and fetal anthropometry do not account for the lack of agreement.ConclusionsAbsolute values of SV as determined by ICG are not valid in pregnancy. Further work is required to examine the ability of ICG to assess relative changes in maternal haemodynamics in late pregnancy.

Highlights

Assessment of stroke volume (SV) is often necessary in clinical and research settings
Echocardiography does not provide a continuous assessment of cardiac function over more than a few minutes and cannot be used in sleep studies
We aimed to examine the agreement between impedance cardiography (ICG) and echocardiography in a cohort of healthy women in late pregnancy

Summary

Introduction

Assessment of stroke volume (SV) is often necessary in clinical and research settings. The clinically established method for SV assessment in pregnancy is echocardiography, but given its limitations, it is not always an appropriate measurement tool. We aimed to test the validity of ICG in a clinically realistic setting in late pregnancy using echocardiography. The assessment and monitoring of stroke volume (SV) and cardiac output (CO) is often useful in research and for patient care. The use of invasive or disruptive methods in assessment of healthy pregnant participants either presents unacceptable risk when not medically indicated, or Echocardiography is clinically well established and provides a detailed and accurate assessment of cardiac structure and function in pregnancy. A non-invasive method that permits continuous measurement, with less operatordependency that can be used in ambulatory settings would be advantageous

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