Item | Mild | Moderate | Severe |
---|---|---|---|
Onset time | Respiratory symptoms developed/aggravated within 1 week after clinically known damage | ||
Hypoxemia | PaO2/FiO2 201–300 mmHg, PEEP or CPAP ≥5 cmH2O | PaO2/FiO2 101–200 mmHg, PEEP≥5 cmH2O | PaO2/FiO2 ≤ 100 mmHg, PEEP≥10 cmH2O |
Causes of pulmonary edema | Respiratory failure cannot be completely explained by heart failure or fluid overload. Objective assessment (such as echocardiography) is needed to eliminate the possibility of hydrostatic pulmonary edema if other risk factor is absent. | ||
Abnormality in imaging | Decreased transparence of two lungs cannot be completely explained by pleural effusion, atelectasis or nodules. |