Table 1 Berlin Definition of acute respiratory distress syndrome

Timing

Within 1 week of a known clinical insult or new/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 or fluid overload; need objective assessment (for example, echocardiography) to exclude hydrostatic oedema if no risk factor present

Oxygenation^b

   Mild

200 <PaO₂/FiO₂ ≤ 300, with PEEP or CPAP ≥ 5 cmH₂O^c

   Moderate

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

   Severe

PaO₂/FiO2 ≤ 100, with PEEP ≥ 5 cmH₂O