Validation of Non-invasive Measurement of Cardiac Output: Using Whole-Body Bio-impedance Versus Inert Gas Rebreathing in Healthy Women Undergoing In Vitro Fertilisation

Raj Kamael Jaspal, Mae Allen, Jerome Cornette, Dimitris Rizopoulos, Christoph Lees*

*Corresponding author for this work

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Abstract

Background: Haemodynamic assessment in and before pregnancy is becoming increasingly important in relation to pregnancy complications and outcomes. Different methodologies exist but there is no gold-standard technique for non-invasive measurement of cardiac output (CO). We sought to assess two methods of CO measurement in healthy women undergoing in vitro fertilisation cycles (IVF). This was a prospective longitudinal study of 71 women aged 18–44 years planning IVF undergoing CO measurements obtained via inert gas rebreathing (IGR) using Innocor and whole-body bio-impedance (WBI) using Nicas to assess the reproducibility between the methods. Four visits occurred at which both techniques were used: initial assessment, embryo transfer, day of pregnancy test and 4 weeks post-transfer (regardless of whether conception occurred). Cross-sectional agreement of the methods was assessed using the calculation of bias, percentage error and limits of agreement (LOA) via the Bland–Altman analysis. Longitudinal agreement of the methods was assessed using a 4-quadrant plot with concordance rate, angular bias and radial limits of agreement (%). Results: One hundred and thirteen measurements from 44 participants were suitable for cross-sectional (Bland–Altman) analysis. IGR (Innocor) Mean CO was 4.61 L/min and 5.05 L/min with WBI (Nicas). The bias was 0.44 L/min. The percentage error was 76% and intra-correlation coefficient was 0.135 (95% CI −0.43–0.306). Fifty-nine measurements from 28 participants were suitable for longitudinal (4Q-plot) analysis. The concordance rate was 64.4%, angular bias – 0.14, and radial limits of agreement + − 13.25°. Conclusion: There was poor cross-sectional and longitudinal agreement between inert gas rebreathing and whole-body bio-impedance techniques. These techniques cannot be used interchangeably when measuring CO in women undergoing IVF, and these results may be more generalizable, to women in the peri-conception period.

Original languageEnglish
Pages (from-to)100-104
Number of pages5
JournalArtery Research
Volume28
Issue number3
DOIs
Publication statusPublished - Sept 2022

Bibliographical note

Funding
Imperial College Health Charity Cardiovascular Grant. No involvement in study design, data collection, analysis or interpretation. Funding for study consumables only. CCL is supported by the NIHR Biomedical Research Centre (BRC) based at Imperial College Healthcare NHS Trust and Imperial College London.

Publisher Copyright: © 2022, The Author(s).

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