Validation of Global Definition of Acute Respiratory Distress Syndrome in COVID-19 Patients: A Retrospective Study

A recent acute respiratory distress syndrome (ARDS) definition included patients receiving high-flow nasal oxygen (HFNO) when fulfilling the oxygenation and radiological criteria of ARDS Berlin definition. However, outcome of patients treated may be better than those who fulfilled the corresponding class of Berlin definition. This study was aimed to compare the survival between patients fulfilling Berlin definition and patients managed by HFNO initially.

Patients fulfilling the World Health Organization case definition of severe or critical COVID-19 infection requiring HFNO (at least 30 L/minute of flow), noninvasive ventilation (NIV) (at least a positive end-expiratory pressure (PEEP) of 5 cm H₂O), or invasive mechanical ventilation (at least a PEEP of 5 cm H₂O) were included in this study provided they fulfilled oxygenation and radiological criteria of ARDS as per Berlin definition.

All-cause hospital mortality rate in patients who fulfilled Berlin definition (n = 193) was 47.6% (mild ARDS), 64.9% (moderate ARDS), and 67.9% (severe ARDS) (p = 0.23). Multivariable survival analysis reported that hazard of death was higher in patients who fulfilled Berlin definition as opposed to those who were initially managed by HFNO (adjusted hazard ratio (95% confidence interval) 1.68 (1.15-2.45), p = 0.007) after adjustment for age, Charlson comorbidity index, and baseline PaO₂/FiO₂ ratio. Multiple pairwise comparison reported that hazard of death was lower in patients with moderate ARDS requiring HFNO as compared with the moderate ARDS patients as per Berlin definition (p = 0.024). However, no difference was observed in patients of mild (p = 0.39) and severe ARDS (p = 0.24).

We have found a statistically significant higher survival in ARDS patients managed by HFNO in the first 24 hours after intensive care unit (ICU) admission when compared with the patients receiving NIV or invasive mechanical ventilation. So, we conclude that outcome of patients fulfilling the global definition of ARDS is largely different from those who fulfilled Berlin definition. Hence, prospective multicentric validation is required before its bedside use.

Maitra S, Baidya DK, Ray BR, Kayina CA, Haritha D, Nair PR, et al. Validation of Global Definition of Acute Respiratory Distress Syndrome in COVID-19 Patients: A Retrospective Study. Indian J Crit Care Med 2025;29(7):556-561.