PaO2 / FiO2 ratio responsiveness to prone positioning in intubated patients with severe COVID-19: a retrospective observational study

Akiko Kawakami; Kazuma Yamakawa; Daisuke Nishioka; Koshi Ota; Yusuke Kusaka; Osamu Umegaki; Yuri Ito; Akira Takasu

doi:10.1002/ams2.765

PaO₂ / FiO₂ ratio responsiveness to prone positioning in intubated patients with severe COVID-19: a retrospective observational study

Acute Med Surg. 2022 Jun 4;9(1):e765. doi: 10.1002/ams2.765. eCollection 2022 Jan-Dec.

Authors

Akiko Kawakami¹, Kazuma Yamakawa¹, Daisuke Nishioka², Koshi Ota¹, Yusuke Kusaka³, Osamu Umegaki⁴, Yuri Ito², Akira Takasu¹

Affiliations

¹ Department of Emergency and Critical Care Medicine Osaka Medical and Pharmaceutical University Takatsuki Japan.
² Department of Medical Statistics, Research and Development Center Osaka Medical and Pharmaceutical University Takatsuki Japan.
³ Department of Anesthesiology Osaka Medical and Pharmaceutical University Takatsuki Japan.
⁴ Intensive Care Unit Osaka Medical and Pharmaceutical University Hospital Takatsuki Japan.

Abstract

Aim: Prone positioning of coronavirus disease 2019 (COVID-19) patients could improve oxygenation. However, clinical data on prone positioning of intubated COVID-19 patients are limited. We investigated trends of PaO₂ / FiO₂ ratio values in patients during prone positioning to identify a predictive factor for early detection of patients requiring advanced therapeutic intervention such as extracorporeal membrane oxygenation (ECMO).

Methods: This retrospective, observational cohort study was undertaken between April 2020 and May 2021 in a tertiary referral hospital for COVID-19 in Osaka, Japan. We included intubated adult COVID-19 patients treated with prone positioning within the first 72 h of admission to the intensive care unit and followed them until hospital discharge or death. Primary outcomes were in-hospital mortality and escalation of care to ECMO. We used unsupervised k-means clustering modeling to categorize COVID-19 patients by PaO₂ / FiO₂ ratio responsiveness to prone positioning.

Results: The final study cohort comprised 54 of 155 consecutive severe COVID-19 patients. Three clusters were generated according to trends in PaO₂ / FiO₂ ratios during prone positioning (cluster A, n = 16; cluster B, n = 24; cluster C, n = 14). Baseline characteristics of all clusters were almost similar. Cluster A (no increase in PaO₂ / FiO₂ ratio during prone positioning) had a significantly higher proportion of patients placed on ECMO or who died (6/16, 37.5%). Numbers of patients with ECMO and with in-hospital death were significantly different between the three groups (p = 0.017).

Conclusion: In Japanese patients intubated due to COVID-19, clinicians should consider earlier escalation of treatment, such as facility transfer or ECMO, if the PaO₂ / FiO₂ ratio does not increase during initial prone positioning.

Keywords: Acute respiratory distress syndrome; COVID‐19; ECMO; PaO2 / FiO2 ratio; prone positioning.