Evaluating the Newly Proposed ARDS Definition in Hospitalized Patients With COVID-19 Treated With High-Flow Nasal Oxygen

Background: The new Global definition of ARDS recently introduced a subgroup known as non-intubated ARDS. This study aimed to assess the risk of progression from noninvasive oxygen support to intubation and ARDS severity based on the S_pO2 /F_IO2 among non-intubated subjects with ARDS.

Methods: This retrospective study included subjects with COVID-19 admitted to 7 hospitals (5 in the United States and 2 in Argentina) from January 2020-January 2023. Subjects meeting the new non-intubated ARDS definition (high-flow nasal cannula [HFNC] with an S_pO2 /F_IO2 ≤ 315 [with S_pO2 ≤ 97%] or a P_aO2 /F_IO2 ≤ 300 mm Hg while receiving ≥30 L/min O₂ via HFNC) were included. The study evaluated the proportion of subjects who progressed to intubation, severity levels using the S_pO2 /F_IO2 cutoff proposed in the new ARDS definition, and mortality.

Results: Nine hundred sixty-five non-intubated subjects with ARDS were included, of whom 27% (n = 262) progressed to meet the Berlin criteria within a median of 3 d (interquartile range 2-6). The overall mortality was 23% (95% CI 20-26) (n = 225), and among subjects who progressed to the Berlin criteria, it was 37% (95% CI 31-43) (n = 98). Additionally, the worst S_pO2 /F_IO2 within 1 d of ARDS diagnosis was correlated with mortality, with mortality rates of 26% (95% CI 23-30) (n = 177) for subjects with S_pO2 /F_IO2 ≤ 148, 17% (95% CI 12-23) (n = 38) for those with S_pO2 /F_IO2 between 149-234, and 16% (95% CI 8-28) (n = 10) for subjects maintaining an S_pO2 /F_IO2 higher than 235 (P < .001).

Conclusions: The non-intubated ARDS criteria encompassed a broader spectrum of subjects with lower in-hospital mortality compared to the Berlin criteria. The S_pO2 /F_IO2 and ARDS severity cutoff proposed in the new Global ARDS definition were valuable predictors of in-hospital mortality in these subjects.