Table 1.

Berlin criteria for ARDS

Characteristics	ARDS Berlin definition
Timing	Within 7 days of a known clinical insult or new or worsening respiratory symptoms
Oxygenation	Mild: PaO2/FiO2 >200 mmHg, but ≤300 mmHg;
	Moderate: PaO2 /FiO2 >100 mmHg, but ≤200 mmHg;
	Severe: PaO2 /FiO2 ≤100 mmHg
PEEP requirement	Minimum 5 cm H2O PEEP required by invasive mechanical ventilation
Chest imaging	Bilateral opacities not fully explained by effusions, lobar/lung collapse or nodules by chest radiograph or CT
Origin of edema	Respiratory failure not fully explained by cardiac failure or fluid overload (need objective assessment, such as echocardiography, to exclude hydrostatic edema if no risk factor present)

PEEP: positive end-expiratory pressure; PaO ₂ : arterial oxygen tension; FiO ₂ : inspiratory oxygen fraction; CT: computed to-mography.