Table 2.

Berlin Definition of ARDS. Adapted from Ranieri et al. [44].

Criteria	Explanation
Timing	Within 1 week of a known clinical insult or new or worsening respiratory symptoms
Chest imaging a	Bilateral opacities—not fully explained by effusions, lobar/ lung collapse, or nodules
Origin of oedema	Respiratory failure not fully explained by cardiac failure of fluid overload Need objective assessment (e.g., echocardiography) to exclude hydrostatic oedema if no risk factor present
Oxygenation b	Mild	Moderate	Severe
	200 mmHg < PaO2/FiO2 ≤ 300 mmHg with PEEP or CPAP ≥ 5 cm H2O c	100 mmHg < PaO2/FiO2 ≤ 200 mmHg with PEEP ≥ 5 cm H2O	PaO2/FiO2 ≤ 100 mmHg with PEEP ≥ 5 cm H2O

^a Chest radiography or computed tomography scan; ^b If altitude is higher than 1.000 m, the correction factor should be calculated as follows: [PaO₂/FiO₂ × barometric pressure/760]; ^c This may be delivered noninvasively in the mild acute respiratory distress syndrome group.