Respiratory effects of prone position in COVID-19 acute respiratory distress syndrome differ according to the recruitment-to-inflation ratio: a prospective observational study

Christopher Lai; Rui Shi; Ludwig Jelinski; Florian Lardet; Marta Fasan; Soufia Ayed; Hugo Belotti; Nicolas Biard; Laurent Guérin; Nicolas Fage; Quentin Fossé; Thibaut Gobé; Arthur Pavot; Guillaume Roger; Alex Yhuel; Jean-Louis Teboul; Tai Pham; Xavier Monnet; EVALPRO Study group

doi:10.1186/s13613-024-01375-2

Respiratory effects of prone position in COVID-19 acute respiratory distress syndrome differ according to the recruitment-to-inflation ratio: a prospective observational study

Ann Intensive Care. 2024 Sep 18;14(1):146. doi: 10.1186/s13613-024-01375-2.

Authors

Christopher Lai^{1

2}, Rui Shi^{3

4}, Ludwig Jelinski³, Florian Lardet³, Marta Fasan^{3

5}, Soufia Ayed³, Hugo Belotti³, Nicolas Biard³, Laurent Guérin³, Nicolas Fage³, Quentin Fossé³, Thibaut Gobé³, Arthur Pavot³, Guillaume Roger³, Alex Yhuel³, Jean-Louis Teboul^{3

4}, Tai Pham^{3

6}, Xavier Monnet^{3

4}; EVALPRO Study group

Affiliations

¹ AP-HP, Service de médecine intensive-réanimation, Hôpital de Bicêtre, Hôpitaux Universitaires Paris-Saclay, DMU CORREVE, FHU SEPSIS, Groupe de recherche clinique CARMAS, Université Paris-Saclay, 78 rue du Général Leclerc, 94270, Le Kremlin-Bicêtre, France. christopher.lai@aphp.fr.
² Inserm UMR S_999, Pulmonary Hypertension: Pathophysiology and Novel Therapies, University Paris-Saclay, Hôpital Marie Lannelongue, Le Plessis-Robinson, France. christopher.lai@aphp.fr.
³ AP-HP, Service de médecine intensive-réanimation, Hôpital de Bicêtre, Hôpitaux Universitaires Paris-Saclay, DMU CORREVE, FHU SEPSIS, Groupe de recherche clinique CARMAS, Université Paris-Saclay, 78 rue du Général Leclerc, 94270, Le Kremlin-Bicêtre, France.
⁴ Inserm UMR S_999, Pulmonary Hypertension: Pathophysiology and Novel Therapies, University Paris-Saclay, Hôpital Marie Lannelongue, Le Plessis-Robinson, France.
⁵ Department of Surgery, Dentistry, Gynaecology and Paediatrics, University of Verona, Verona, Veneto, Italy.
⁶ Inserm U1018, Equipe d'Epidémiologie Respiratoire Intégrative, CESP,, Université Paris-Saclay (UVSQ)-Université Paris-Sud, Villejuif, 94807, France.

Abstract

Background: Improvements in oxygenation and lung mechanics with prone position (PP) in patients with acute respiratory distress syndrome (ARDS) are inconstant. The objectives of the study were (i) to identify baseline variables, including the recruitment-to-inflation ratio (R/I), associated with a positive response to PP in terms of oxygenation (improvement of the ratio of arterial oxygen partial pressure over the inspired oxygen fraction (PaO₂/FiO₂) ≥ 20 mmHg) and lung mechanics; (ii) to evaluate whether the response to the previous PP session is associated with the response to the next session.

Methods: In this prospective, observational, single-center study in patients who underwent PP for ARDS due to COVID-19, respiratory variables were assessed just before PP and at the end of the session. Respiratory variables included mechanical ventilation settings and respiratory mechanics variables, including R/I, an estimate of the potential for lung recruitment compared to lung overinflation.

Results: In 50 patients, 201 PP sessions lasting 19 ± 3 h were evaluated. Neuromuscular blockades were used in 116 (58%) sessions. The PaO₂/FiO₂ ratio increased from 109 ± 31 mmHg to 165 ± 65 mmHg, with an increase ≥ 20 mmHg in 142 (71%) sessions. In a mixed effect logistic regression, only pre-PP PaO₂/FiO₂ (OR 1.12 (95% CI [1.01-1.24])/every decrease of 10 mmHg, p = 0.034) in a first model and improvement in oxygenation at the previous PP session (OR 3.69 (95% CI [1.27-10.72]), p = 0.017) in a second model were associated with an improvement in oxygenation with PP. The R/I ratio (n = 156 sessions) was 0.53 (0.30-0.76), separating lower- and higher-recruiters. Whereas PaO₂/FiO₂ improved to the same level in both subgroups, driving pressure and respiratory system compliance improved only in higher-recruiters (from 14 ± 4 to 12 ± 4 cmH₂O, p = 0.027, and from 34 ± 11 to 38 ± 13 mL/cmH₂O, respectively, p = 0.014).

Conclusions: A lower PaO₂/FiO₂ at baseline and a positive O₂-response at the previous PP session are associated with a PP-induced improvement in oxygenation. In higher-recruiters, lung mechanics improved along with oxygenation. Benefits of PP could thus be greater in these patients.

Keywords: Airway opening pressure; Driving pressure; Heart-lung interactions; Lung recruitment.