The definition of Acute Respiratory Distress Syndrome2
| 1 | Acute onset of impaired oxygenation within one week of insult |
| 2 | Severe hypoxaemia defined as a ratio of PaO2:FIO2 of ≤40 kPa (300 mm Hg) |
| 3 | Bilateral opacities on the chest radiograph |
| 4 | Respiratory failure not fully explained by heart failure or fluid overload |