Fig. 1.

Change of severity classifications when P/FP ratio is used instead of P/F ratio for severities. Severe refers to a ratio of ≤ 100, moderate refers to a ratio of 101–200, mild refers to a ratio of 201–300, non-ARDS refers to a ratio of > 300 mmHg or mmHg/cmH₂O. Green ovals represent patients who were reclassified to a more severe category. Blue ovals represent patients who were reclassified to a milder category. Red ovals represent patients whose categories remained unchanged. Definition of abbreviations: ARDS  acute respiratory distress syndrome; P/F  ratio of the partial pressure of arterial oxygen (PaO₂) to the fraction of inspired oxygen (FiO₂); P/FP = (PaO₂ * 10)/(FiO₂ * positive end-expiratory pressure)