2.5 Heavy group diagnostic criteria
Patients presented with general group diagnostic criteria and any one of the following:
  1. Respiratory rate ≥ 30/min at rest.
  2. Oxygen saturation (SpO2) ≤ 93% on room air.
  3. Arterial oxygen partial pressure (PaO2)/oxygen uptake concentration (FiO2) [PaO2/FiO2] (PF ratio) ≤ 300.