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Paradoxical Positioning: Does “Head Up” Always Improve Mechanics and Lung Protection?*
Head-elevated body positioning, a default clinical practice, predictably increases end-expiratory transpulmonary pressure and aerated lung volume. In acute respiratory distress syndrome (ARDS), however, the net effect of such vertical inclination on tidal mechanics depends upon whether lung recruitm...
Autores principales: | , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Lippincott Williams & Wilkins
2022
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9555829/ https://www.ncbi.nlm.nih.gov/pubmed/35866650 http://dx.doi.org/10.1097/CCM.0000000000005631 |
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author | Selickman, John Crooke, Philip S. Tawfik, Pierre Dries, David J. Gattinoni, Luciano Marini, John J. |
author_facet | Selickman, John Crooke, Philip S. Tawfik, Pierre Dries, David J. Gattinoni, Luciano Marini, John J. |
author_sort | Selickman, John |
collection | PubMed |
description | Head-elevated body positioning, a default clinical practice, predictably increases end-expiratory transpulmonary pressure and aerated lung volume. In acute respiratory distress syndrome (ARDS), however, the net effect of such vertical inclination on tidal mechanics depends upon whether lung recruitment or overdistension predominates. We hypothesized that in moderate to severe ARDS, bed inclination toward vertical unloads the chest wall but adversely affects overall respiratory system compliance (Crs). DESIGN: Prospective physiologic study. SETTING: Two medical ICUs in the United States. PATIENTS: Seventeen patients with ARDS, predominantly moderate to severe. INTERVENTION: Patients were ventilated passively by volume control. We measured airway pressures at baseline (noninclined) and following bed inclination toward vertical by an additional 15°. At baseline and following inclination, we manually loaded the chest wall to determine if Crs increased or paradoxically declined, suggestive of end-tidal overdistension. MEASUREMENTS AND MAIN RESULTS: Inclination resulted in a higher plateau pressure (supineΔ: 2.8 ± 3.3 cm H(2)O [p = 0.01]; proneΔ: 3.3 ± 2.5 cm H(2)O [p = 0.004]), higher driving pressure (supineΔ: 2.9 ± 3.3 cm H(2)O [p = 0.01]; proneΔ: 3.3 ± 2.8 cm H(2)O [p = 0.007]), and lower Crs (supine Δ: 3.4 ± 3.7 mL/cm H(2)O [p = 0.01]; proneΔ: 3.1 ± 3.2 mL/cm H(2)O [p = 0.02]). Following inclination, manual loading of the chest wall restored Crs and driving pressure to baseline (preinclination) values. CONCLUSIONS: In advanced ARDS, bed inclination toward vertical adversely affects Crs and therefore affects the numerical values for plateau and driving tidal pressures commonly targeted in lung protective strategies. These changes are fully reversed with manual loading of the chest wall, suggestive of end-tidal overdistension in the upright position. Body inclination should be considered a modifiable determinant of transpulmonary pressure and lung protection, directionally similar to tidal volume and positive end-expiratory pressure. |
format | Online Article Text |
id | pubmed-9555829 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2022 |
publisher | Lippincott Williams & Wilkins |
record_format | MEDLINE/PubMed |
spelling | pubmed-95558292022-10-19 Paradoxical Positioning: Does “Head Up” Always Improve Mechanics and Lung Protection?* Selickman, John Crooke, Philip S. Tawfik, Pierre Dries, David J. Gattinoni, Luciano Marini, John J. Crit Care Med Clinical Investigations Head-elevated body positioning, a default clinical practice, predictably increases end-expiratory transpulmonary pressure and aerated lung volume. In acute respiratory distress syndrome (ARDS), however, the net effect of such vertical inclination on tidal mechanics depends upon whether lung recruitment or overdistension predominates. We hypothesized that in moderate to severe ARDS, bed inclination toward vertical unloads the chest wall but adversely affects overall respiratory system compliance (Crs). DESIGN: Prospective physiologic study. SETTING: Two medical ICUs in the United States. PATIENTS: Seventeen patients with ARDS, predominantly moderate to severe. INTERVENTION: Patients were ventilated passively by volume control. We measured airway pressures at baseline (noninclined) and following bed inclination toward vertical by an additional 15°. At baseline and following inclination, we manually loaded the chest wall to determine if Crs increased or paradoxically declined, suggestive of end-tidal overdistension. MEASUREMENTS AND MAIN RESULTS: Inclination resulted in a higher plateau pressure (supineΔ: 2.8 ± 3.3 cm H(2)O [p = 0.01]; proneΔ: 3.3 ± 2.5 cm H(2)O [p = 0.004]), higher driving pressure (supineΔ: 2.9 ± 3.3 cm H(2)O [p = 0.01]; proneΔ: 3.3 ± 2.8 cm H(2)O [p = 0.007]), and lower Crs (supine Δ: 3.4 ± 3.7 mL/cm H(2)O [p = 0.01]; proneΔ: 3.1 ± 3.2 mL/cm H(2)O [p = 0.02]). Following inclination, manual loading of the chest wall restored Crs and driving pressure to baseline (preinclination) values. CONCLUSIONS: In advanced ARDS, bed inclination toward vertical adversely affects Crs and therefore affects the numerical values for plateau and driving tidal pressures commonly targeted in lung protective strategies. These changes are fully reversed with manual loading of the chest wall, suggestive of end-tidal overdistension in the upright position. Body inclination should be considered a modifiable determinant of transpulmonary pressure and lung protection, directionally similar to tidal volume and positive end-expiratory pressure. Lippincott Williams & Wilkins 2022-11 2022-10-13 /pmc/articles/PMC9555829/ /pubmed/35866650 http://dx.doi.org/10.1097/CCM.0000000000005631 Text en Copyright © 2022 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the Society of Critical Care Medicine and Wolters Kluwer Health, Inc. https://creativecommons.org/licenses/by-nc-nd/4.0/This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND) (https://creativecommons.org/licenses/by-nc-nd/4.0/) , where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal. |
spellingShingle | Clinical Investigations Selickman, John Crooke, Philip S. Tawfik, Pierre Dries, David J. Gattinoni, Luciano Marini, John J. Paradoxical Positioning: Does “Head Up” Always Improve Mechanics and Lung Protection?* |
title | Paradoxical Positioning: Does “Head Up” Always Improve Mechanics and Lung Protection?* |
title_full | Paradoxical Positioning: Does “Head Up” Always Improve Mechanics and Lung Protection?* |
title_fullStr | Paradoxical Positioning: Does “Head Up” Always Improve Mechanics and Lung Protection?* |
title_full_unstemmed | Paradoxical Positioning: Does “Head Up” Always Improve Mechanics and Lung Protection?* |
title_short | Paradoxical Positioning: Does “Head Up” Always Improve Mechanics and Lung Protection?* |
title_sort | paradoxical positioning: does “head up” always improve mechanics and lung protection?* |
topic | Clinical Investigations |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9555829/ https://www.ncbi.nlm.nih.gov/pubmed/35866650 http://dx.doi.org/10.1097/CCM.0000000000005631 |
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