Table 1 Berlin definition

Timing

Within 1 week of a known clinical insult or new or worsening respiratory symptoms

Chest imaging

Bilateral opacities—not fully explained by effusions, lobar/lung collapse, or nodules

Origin of edema

Respiratory failure not fully explained by cardiac dysfunction or fluid overload

Oxygenation

Mild

200 mmHg < PaO₂/FiO₂ ≤ 300 mmHg with PEEP/CPAP ≥ 5cmH₂O

Moderate

100 mmHg < PaO₂/FiO₂ ≤ 200 mmHg with PEEP ≥ 5cmH₂O

Severe

PaO₂/FiO₂ ≤ 100 mmHg with PEEP ≥ 5cmH₂O