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Journal of Clinical Monitoring and Computing

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Open Access 01-10-2017 | Original Research

Analysis and compensation for errors in electrical impedance tomography images and ventilation-related measures due to serial data collection

Authors: Rebecca J. Yerworth, Inéz Frerichs, Richard Bayford

Published in: Journal of Clinical Monitoring and Computing | Issue 5/2017

Abstract

Electrical impedance tomography (EIT) is increasingly being used as a bedside tool for monitoring regional lung ventilation. However, most clinical systems use serial data collection which, if uncorrected, results in image distortion, particularly at high breathing rates. The objective of this study was to determine the extent to which this affects derived parameters. Raw EIT data were acquired with the GOE-MF II EIT device (CareFusion, Höchberg, Germany) at a scan rate of 13 images/s during both spontaneous breathing and mechanical ventilation. Boundary data for periods of undisturbed tidal breathing were corrected for serial data collection errors using a Fourier based algorithm. Images were reconstructed for both the corrected and original data using the GREIT algorithm, and parameters describing the filling characteristics of the right and left lung derived on a breath by breath basis. Values from the original and corrected data were compared using paired t-tests. Of the 33 data sets, 23 showed significant differences in filling index for at least one region, 11 had significant differences in calculated tidal impedance change and 12 had significantly different filling fractions (p = 0.05). We conclude that serial collection errors should be corrected before image reconstruction to avoid clinically misleading results.

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For a breathing rate of 60 breaths per minute, i.e. 1 breath per second, if inspiration and expiration phases are equal there are 6–7 data points during the inspiratory phase and 6–7 during the expiratory. This corresponds to a change of >1/6th (17 %) of the inspired volume occurring during a single frame of data collection. However the inspiratory phase is often shorter than the expiratory, so this is an underestimate of the physiological changes present.

Most recently developed commercial EIT devices do not offer specific electrode interfaces for neonates, therefore these older EIT devices are the only ones available for this patient population.

A more sophisticated breath detection approach would be needed for unsupervised use and non-tidal breathing.

Available from EIDORS http://eidors3d.sourceforge.net/ or by contacting the authors..

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Title: Analysis and compensation for errors in electrical impedance tomography images and ventilation-related measures due to serial data collection
Authors: Rebecca J. Yerworth
Inéz Frerichs
Richard Bayford
Publication date: 01-10-2017
Publisher: Springer Netherlands
Published in: Journal of Clinical Monitoring and Computing / Issue 5/2017
Print ISSN: 1387-1307
Electronic ISSN: 1573-2614
DOI: https://doi.org/10.1007/s10877-016-9920-y

At a glance: The STEP trials

Springer Medicine

Analysis and compensation for errors in electrical impedance tomography images and ventilation-related measures due to serial data collection

Abstract

At a glance: The STEP trials

Springer Medicine

Abstract

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