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Clinical Trial
. 2023 Sep 4;27(1):343.
doi: 10.1186/s13054-023-04623-2.

Advanced respiratory mechanics assessment in mechanically ventilated obese and non-obese patients with or without acute respiratory distress syndrome

François M Beloncle  1   2 , Jean-Christophe Richard  3   4 , Hamid Merdji  5   6 , Christophe Desprez  3 , Bertrand Pavlovsky  3 , Elise Yvin  3 , Lise Piquilloud  7 , Pierre-Yves Olivier  3 , Dara Chean  3 , Antoine Studer  5 , Antonin Courtais  3 , Maëva Campfort  3 , Hassene Rahmani  5 , Arnaud Lesimple  8   4 , Ferhat Meziani  5   6 , Alain Mercat  3
Affiliations
Clinical Trial

Advanced respiratory mechanics assessment in mechanically ventilated obese and non-obese patients with or without acute respiratory distress syndrome

François M Beloncle et al. Crit Care. .

Abstract

Background: Respiratory mechanics is a key element to monitor mechanically ventilated patients and guide ventilator settings. Besides the usual basic assessments, some more complex explorations may allow to better characterize patients' respiratory mechanics and individualize ventilation strategies. These advanced respiratory mechanics assessments including esophageal pressure measurements and complete airway closure detection may be particularly relevant in critically ill obese patients. This study aimed to comprehensively assess respiratory mechanics in obese and non-obese ICU patients with or without ARDS and evaluate the contribution of advanced respiratory mechanics assessments compared to basic assessments in these patients.

Methods: All intubated patients admitted in two ICUs for any cause were prospectively included. Gas exchange and respiratory mechanics including esophageal pressure and end-expiratory lung volume (EELV) measurements and low-flow insufflation to detect complete airway closure were assessed in standardized conditions (tidal volume of 6 mL kg-1 predicted body weight (PBW), positive end-expiratory pressure (PEEP) of 5 cmH2O) within 24 h after intubation.

Results: Among the 149 analyzed patients, 52 (34.9%) were obese and 90 (60.4%) had ARDS (65.4% and 57.8% of obese and non-obese patients, respectively, p = 0.385). A complete airway closure was found in 23.5% of the patients. It was more frequent in obese than in non-obese patients (40.4% vs 14.4%, p < 0.001) and in ARDS than in non-ARDS patients (30% vs. 13.6%, p = 0.029). Respiratory system and lung compliances and EELV/PBW were similarly decreased in obese patients without ARDS and obese or non-obese patients with ARDS. Chest wall compliance was not impacted by obesity or ARDS, but end-expiratory esophageal pressure was higher in obese than in non-obese patients. Chest wall contribution to respiratory system compliance differed widely between patients but was not predictable by their general characteristics.

Conclusions: Most respiratory mechanics features are similar in obese non-ARDS and non-obese ARDS patients, but end-expiratory esophageal pressure is higher in obese patients. A complete airway closure can be found in around 25% of critically ill patients ventilated with a PEEP of 5 cmH2O. Advanced explorations may allow to better characterize individual respiratory mechanics and adjust ventilation strategies in some patients. Trial registration NCT03420417 ClinicalTrials.gov (February 5, 2018).

Keywords: Acute lung injury; Airway closure; Chest wall mechanic; Esophageal pressure; Mechanical ventilation; Pleural pressure.

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Conflict of interest statement

FB reports consulting fees from Löwenstein Medical and Air Liquid Medical Systems and research support from Covidien and Getinge Group, outside this work, and research support from GE Healthcare related to this work. JCR reports part‐time salary for research activities from Air Liquide Medical Systems and grants from Creative Air Liquide, outside this work. PYO reports personal fees from Air Liquid Medical Systems, outside this work. AL is a PhD student in the Med2Lab partially funded by Air Liquide Medical Systems. AM reports personal fees from Faron Pharmaceuticals, Air Liquid Medical Systems, Pfizer, Resmed, and Draeger and grants and personal fees from Fisher and Paykel and Covidien, outside this work. The other authors have no conflict of interest to declare.

Figures

Fig. 1
Fig. 1
Distribution of respiratory system compliance (CRS/PBW, A), lung compliance (CL/PBW, B), and end-expiratory lung volume (EELV/PBW, C) normalized to predicted body weight in patients categorized according to the presence or not of obesity and acute respiratory distress syndrome (ARDS). Boxplots display medians, 10th, 25th, 75th, and 90th percentiles. p-values represent the overall comparisons between the four groups of patients. *, p < 0.05; **, p < 0.01; ***, p < 0.001 (pairwise comparisons with Bonferroni correction)
Fig. 2
Fig. 2
Distribution of chest wall compliance (CCW, A) and end-expiratory esophageal pressure (Peso expi, B) in patients categorized according to the presence or not of obesity and acute respiratory distress syndrome (ARDS). Boxplots display medians, 10th, 25th, 75th, and 90th percentiles. p-values represent the overall comparisons between the four groups of patients. *, p < 0.05 (pairwise comparisons with Bonferroni correction)
Fig. 3
Fig. 3
Esophageal pressure–volume (A) and esophageal pressure–time (B) curves during low-flow insufflation (5L min−1) in obese and non-obese patients. A Black and gray lines represent median values of all obese and non-obese patients included in the study, respectively. B Black and gray lines represent median values and interquartile range of all obese and non-obese patients included in the study, respectively
See this image and copyright information in PMC

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