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Regional expiratory time constants in severe respiratory failure estimated by electrical impedance tomography: a feasibility study
BACKGROUND: Electrical impedance tomography (EIT) has been used to guide mechanical ventilation in ICU patients with lung collapse. Its use in patients with obstructive pulmonary diseases has been rare since obstructions could not be monitored on a regional level at the bedside. The current study th...
Autores principales: | , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
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BioMed Central
2018
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6148957/ https://www.ncbi.nlm.nih.gov/pubmed/30236123 http://dx.doi.org/10.1186/s13054-018-2137-3 |
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author | Karagiannidis, Christian Waldmann, Andreas D. Róka, Péter L. Schreiber, Tina Strassmann, Stephan Windisch, Wolfram Böhm, Stephan H. |
author_facet | Karagiannidis, Christian Waldmann, Andreas D. Róka, Péter L. Schreiber, Tina Strassmann, Stephan Windisch, Wolfram Böhm, Stephan H. |
author_sort | Karagiannidis, Christian |
collection | PubMed |
description | BACKGROUND: Electrical impedance tomography (EIT) has been used to guide mechanical ventilation in ICU patients with lung collapse. Its use in patients with obstructive pulmonary diseases has been rare since obstructions could not be monitored on a regional level at the bedside. The current study therefore determines breath-by-breath regional expiratory time constants in intubated patients with chronic obstructive pulmonary disease (COPD) and acute respiratory distress syndrome (ARDS). METHODS: Expiratory time constants calculated from the global impedance EIT signal were compared to the pneumatic volume signals measured with an electronic pneumotachograph. EIT-derived expiratory time constants were additionally determined on a regional and pixelwise level. However, regional EIT signals on a single pixel level could in principle not be compared with similar pneumatic changes since these measurements cannot be obtained in patients. For this study, EIT measurements were conducted in 14 intubated patients (mean Simplified Acute Physiology Score II (SAPS II) 35 ± 10, mean time on invasive mechanical ventilation 36 ± 26 days) under four different positive end-expiratory pressure (PEEP) levels ranging from 10 to 17 cmH(2)O. Only patients with moderate-severe ARDS or COPD exacerbation were included into the study, preferentally within the first days following intubation. RESULTS: Spearman’s correlation coefficient for comparison between EIT-derived time constants and those from flow/volume curves was between 0.78 for tau (τ) calculated from the global impedance signal up to 0.83 for the mean of all pixelwise calculated regional impedance changes over the entire PEEP range. Furthermore, Bland-Altman analysis revealed a corresponding bias of 0.02 and 0.14 s within the limits of agreement ranging from − 0.50 to 0.65 s for the aforementioned calculation methods. In addition, exemplarily in patients with moderate-severe ARDS or COPD exacerbation, different PEEP levels were shown to have an influence on the distribution pattern of regional time constants. CONCLUSIONS: EIT-based determination of breath-by-breath regional expiratory time constants is technically feasible, reliable and valid in invasively ventilated patients with severe respiratory failure and provides a promising tool to individually adjust mechanical ventilation in response to the patterns of regional airflow obstruction. TRIAL REGISTRATION: German Trial Register DRKS 00011650, registered 01/31/17. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s13054-018-2137-3) contains supplementary material, which is available to authorized users. |
format | Online Article Text |
id | pubmed-6148957 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2018 |
publisher | BioMed Central |
record_format | MEDLINE/PubMed |
spelling | pubmed-61489572018-09-24 Regional expiratory time constants in severe respiratory failure estimated by electrical impedance tomography: a feasibility study Karagiannidis, Christian Waldmann, Andreas D. Róka, Péter L. Schreiber, Tina Strassmann, Stephan Windisch, Wolfram Böhm, Stephan H. Crit Care Research BACKGROUND: Electrical impedance tomography (EIT) has been used to guide mechanical ventilation in ICU patients with lung collapse. Its use in patients with obstructive pulmonary diseases has been rare since obstructions could not be monitored on a regional level at the bedside. The current study therefore determines breath-by-breath regional expiratory time constants in intubated patients with chronic obstructive pulmonary disease (COPD) and acute respiratory distress syndrome (ARDS). METHODS: Expiratory time constants calculated from the global impedance EIT signal were compared to the pneumatic volume signals measured with an electronic pneumotachograph. EIT-derived expiratory time constants were additionally determined on a regional and pixelwise level. However, regional EIT signals on a single pixel level could in principle not be compared with similar pneumatic changes since these measurements cannot be obtained in patients. For this study, EIT measurements were conducted in 14 intubated patients (mean Simplified Acute Physiology Score II (SAPS II) 35 ± 10, mean time on invasive mechanical ventilation 36 ± 26 days) under four different positive end-expiratory pressure (PEEP) levels ranging from 10 to 17 cmH(2)O. Only patients with moderate-severe ARDS or COPD exacerbation were included into the study, preferentally within the first days following intubation. RESULTS: Spearman’s correlation coefficient for comparison between EIT-derived time constants and those from flow/volume curves was between 0.78 for tau (τ) calculated from the global impedance signal up to 0.83 for the mean of all pixelwise calculated regional impedance changes over the entire PEEP range. Furthermore, Bland-Altman analysis revealed a corresponding bias of 0.02 and 0.14 s within the limits of agreement ranging from − 0.50 to 0.65 s for the aforementioned calculation methods. In addition, exemplarily in patients with moderate-severe ARDS or COPD exacerbation, different PEEP levels were shown to have an influence on the distribution pattern of regional time constants. CONCLUSIONS: EIT-based determination of breath-by-breath regional expiratory time constants is technically feasible, reliable and valid in invasively ventilated patients with severe respiratory failure and provides a promising tool to individually adjust mechanical ventilation in response to the patterns of regional airflow obstruction. TRIAL REGISTRATION: German Trial Register DRKS 00011650, registered 01/31/17. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s13054-018-2137-3) contains supplementary material, which is available to authorized users. BioMed Central 2018-09-21 /pmc/articles/PMC6148957/ /pubmed/30236123 http://dx.doi.org/10.1186/s13054-018-2137-3 Text en © The Author(s). 2018 Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. |
spellingShingle | Research Karagiannidis, Christian Waldmann, Andreas D. Róka, Péter L. Schreiber, Tina Strassmann, Stephan Windisch, Wolfram Böhm, Stephan H. Regional expiratory time constants in severe respiratory failure estimated by electrical impedance tomography: a feasibility study |
title | Regional expiratory time constants in severe respiratory failure estimated by electrical impedance tomography: a feasibility study |
title_full | Regional expiratory time constants in severe respiratory failure estimated by electrical impedance tomography: a feasibility study |
title_fullStr | Regional expiratory time constants in severe respiratory failure estimated by electrical impedance tomography: a feasibility study |
title_full_unstemmed | Regional expiratory time constants in severe respiratory failure estimated by electrical impedance tomography: a feasibility study |
title_short | Regional expiratory time constants in severe respiratory failure estimated by electrical impedance tomography: a feasibility study |
title_sort | regional expiratory time constants in severe respiratory failure estimated by electrical impedance tomography: a feasibility study |
topic | Research |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6148957/ https://www.ncbi.nlm.nih.gov/pubmed/30236123 http://dx.doi.org/10.1186/s13054-018-2137-3 |
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