Stage 4 ARDS Outbreak or worsening of respiratory symptoms within 1 week after first clinical manifestation.
Imaging: bilateral radiopacity not related to effusion, atelectasis or consolidations.
Origin of edema: respiratory failure not related to heart failure or fluid overload.
Oxygenation:
- mild ARDS: 200 mmHg < PaO2 / FiO2 ≤ 300 mmHg
- moderated ARDS: 100 mmHg < PaO2/FiO2 ≤ 200 mmHg
- severe ARDS: PaO2/FiO2 ≤ 100 mmHg
- When PaO2 is not available, SpO2/FiO2 ≤ 315 suggests ARDS