Table 1.

ARDS Berlin definition

The Berlin definition of acute respiratory distress syndrome
Timing	Within I week of a known clinical insult or new or worsening respiratory symptoms
Chest imaginga	Bilateral opacities-not fully explained by effusions, lobar/lung collapse, or nodules
Origin of edema	Respiratory failure not fully explained by cardiac failure or fluid overload. Need objective assessment (e.g. echocardiography) to exclude hydrostatic oedema if no risk factor present
Oxygenationb
Mild	200 mmHg <PaO2/FiO2 ≤300 mmHg with PEEP or CPAP ≥5 cmH2Oc
Moderate	100 mmHg <PaO2/FiO2 ≤200 mmHg with PEEP ≥5 cmH2O
Severe	PaO2/FiO2 ≤100 mmHg with PEEP ≥5 cmH2O

CPAP: continuous positive airway pressure; FiO₂: fraction of inspired oxygen; PaO₂: partial pressure of arterial oxygen; PEEP: positive end expiratory pressure;

^aChest radiograph or computed tomography scan;

^bIf altitude is higher than 1,000 m, the correction factor should be calculated as follows: [PaO₂/FiO₂− (barometric pressure/760)];

^cThis may be delivered noninvasively in the mild acute respiratory distress syndrome group.