RESEARCH ARTICLE


Feasibility and Interest of Continuous Diaphragmatic Fatigue Monitoring Using Wavelet Denoising in ICU and Anesthesia



Guy-Louis Morel4, *, Philippe Mahul1, Marcelle Reche3, Jean-Paul Viale2, Christian Auboyer1, Andre Geyssant4, Frederic Roche3, Jean-Claude Barthelemy3, Vincent Pichot3
1 Intensive Care Unit, North Hospital, University Hospital, Saint-Etienne, PRES Lyon, France
2 Surgical Intensive Care Unit, Croix-Rousse Hospital, University Hospital, PRES Lyon, France
3 University North Hospital, Clinical and Exercise Physiology, and University Jean Monnet, EA4607, SNA-EPIS, PRES Lyon, France
4 Exercise Physiology Laboratory, EA4338, and SNA-EPIS EA4607, University Jean Monnet, Saint-Etienne, PRES Lyon, France


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Creative Commons License
© 2013 Morel et al.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: https://creativecommons.org/licenses/by/4.0/legalcode. This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the Exercise and Physiology Laboratory, CHU Nord, 42055 Saint-Etienne, France; Tel: +33 477 828 300; Fax: +33 477 828 447; E-mail: guy.morel@univ-st-etienne.fr


Abstract

Measures of diaphragmatic electromyography (Edi), and respiratory mechanics, have demonstrated early changes before clinical complications. However, automatic Edi data collection is not adequate today due mainly to severe artefacts as well as to loss of signal. We thus intended to develop a new device with embedded artificial intelligence to optimize automatic Edi recordings independantly of artefacts and of probe displacement.

We first chose the best mathematical tool to denoise Edi, using an established database, giving multiresolution wavelets as the best, resulting in the permanent availability of the H/L spectral index, a recognized representative of diaphragmatic fatigue. Fatigue was simultaneously measured using the classical mechanical f/Vt index (Rapid Shallow Breathing Index, RSBI), as well as the transdiaphragmatic pressure.

We then performed a comparison of real-time H/L and RSBI in a group of seven healthy volunteers, before and during midazolam sedation infusion 0.1 mg.kg-1, with a parallel CPAP administration (2.5, 5.0, and 10 cm H2O) intended to compensate for airways resistance due to midazolam. Procedure was ended by delivering the antagonistic flumazenil 0.2 to 0.5 mg.kg-1. Progressive fatigue due to midazolam, the relief due to CPAP, as well as the answer to the anatgonist flumazenil, were shown earlier by the H/L index than by the RSBI change.

Our new H/L monitoring device may greatly improve clinical follow-up of anesthetized patients as well as help to determine the optimal period for ventilatory weaning in ICU (Clinical Trials NCT00133939).

Keywords: Diaphragmatic fatigue, electromyography, respiratory assistance, wavelets denoising, ventilatory weaning.