Table 1. ARDS Berlin Definition.

Timing	Acute onset: within one week of a known clinical insult or new/worsening respiratory symptoms
Chest imaging	Bilateral opacities visible (on chest radiograph or computed tomography scan), not fully explained by effusions, nodules, masses, or lobar/lung collapse
Origin of edema	Respiratory failure associated to known risk factors and not fully explained by cardiac failure or fluid overload. Need objective assessment (e.g., echocardiography) to exclude hydrostatic edema if no risk factor present
Oxygenation
Mild	200 mmHg < PaO2/FiO2 <300 mmHg with PEEP >5 cmH2O
Moderate	100 mmHg < PaO2/FiO2 <200 mmHg with PEEP >5 cmH2O
Severe	PaO2/FiO2 <100 mmHg with PEEP >5 cmH2O