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

• Published in: Annals of intensive care Vol. 14; no. 1; pp. 146 - 10
• Main Authors: Lai, Christopher, Shi, Rui, Jelinski, Ludwig, Lardet, Florian, Fasan, Marta, Ayed, Soufia, Belotti, Hugo, Biard, Nicolas, Guérin, Laurent, Fage, Nicolas, Fossé, Quentin, Gobé, Thibaut, Pavot, Arthur, Roger, Guillaume, Yhuel, Alex, Teboul, Jean-Louis, Pham, Tai, Monnet, Xavier
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 18-09-2024; Springer Nature B.V; SpringerOpen
• Subjects: Airway opening pressure; Anesthesiology; COVID-19; Critical Care Medicine; Driving pressure; Emergency Medicine; Heart-lung interactions; Intensive; Lung recruitment; Mechanics; Medicine; Medicine & Public Health; Respiratory distress syndrome; Heart-lung interactions; Airway opening pressure; Driving pressure; Lung recruitment
• ISSN: 2110-5820; 2110-5820
• DOI: 10.1186/s13613-024-01375-2

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 (PaO
2
/FiO
2
) ≥ 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 PaO
2
/FiO
2
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 PaO
2
/FiO
2
(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 PaO
2
/FiO
2
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 cmH
2
O,
p
 = 0.027, and from 34 ± 11 to 38 ± 13 mL/cmH
2
O, respectively,
p
 = 0.014).
Conclusions
A lower PaO
2
/FiO
2
at baseline and a positive O
2
-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.