Table 1.

The Berlin definition of acute respiratory distress syndrome

Note: Reproduced from ARDS Definition Taskforce et al. [5]

ARDS severity	Mild	Moderate	Severe
Timing	Acute onset within 1 week of a known clinical insult or new/worsening respiratory symptoms
Chest imaginga	Bilateral opacities—not fully explained by effusions, lobar/lung collapse, or nodules
Oxygenationb	PaO2/FiO2 201–300 mmHg with PEEP/CPAP ≥ 5 cm H2Oc	PaO2/FiO2 101–200 mmHg with PEEP/CPAP ≥ 5 cm H2O	PaO2/FiO2 ≤ 100 mmHg with PEEP/CPAP ≥ 5 cm H2O
Origin of oedema	Respiratory failure not fully explained by cardiac failure or fluid overload (objective assessment required if no ARDS risk factor present)

^aChest radiograph or computed tomography scan

^bIf altitude is higher than 1000 m, the correction factor should be calculated as follows: [PaO₂/FiO₂_(barometric pressure/760)]

^cThis may be delivered non-invasively in the mild acute respiratory distress syndrome group