Photo Credit: wmf

The following is a summary of “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 the September 2024 issue of Critical Care by Lai et al.

The significance of prone position (PP) in improving oxygenation and lung mechanics in patients with acute respiratory distress syndrome (ARDS) must be more consistent.

Researchers conducted a retrospective study to identify baseline variables, with recruitment-to-inflation ratio (R/I), linked with a positive response to the 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 and to evaluate whether the response to the previous PP session is related to to the next session. 

They examined patients with COVID-19-induced ARDS who underwent a PP. Respiratory variables were estimated before and after each PP session, which included mechanical ventilation settings and respiratory mechanics variables, such as the (R/I), an estimate of the potential for lung recruitment compared to lung overinflation.

The results showed 201 PP sessions evaluated in 50 patients, averaging 19 ± 3 hours each. Neuromuscular blockades were employed in 116 (58%) sessions. The PaO₂/FiO₂ ratio improved from 109 ± 31 mmHg to 165 ± 65 mmHg, with a rise of ≥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] for every 10 mmHg decrease, P=0.034) and improvement in oxygenation from the prior PP session (OR 3.69 [95% CI 1.27–10.72], P=0.017) were linked to enhanced oxygenation with PP. The recruitment index (R/I ratio, n=156 sessions) was 0.53 (0.30–0.76), distinguishing lower- from higher recruiters, while the PaO₂/FiO₂ ratio improved similarly in both subgroups, driving pressure and respiratory system compliance enhanced only in higher-recruiters (from 14 ± 4 to 12 ± 4 cmH2₂O, P=0.027, and from 34 ± 11 to 38 ± 13 mL/cmH₂O, P=0.014).

They concluded that a lower PaO₂/FiO₂ at baseline and a positive O₂ response at the previous PP session were linked with a PP-induced improvement in oxygenation, suggesting the benefits of the PP be more significant. 

Source: annalsofintensivecare.springeropen.com/articles/10.1186/s13613-024-01375-2