Bilateral opacities not fully explained by effusion, collapse or nodules, within a week of an insult (Berlin definition); CT shows a gradient from normal non-dependent lung to dependent consolidation, and imaging tracks barotrauma and line position.
Orient first
- The Berlin definition needs timing, bilateral opacities, a non-cardiac cause of oedema and hypoxaemia (verify the definition your ICU uses).
- Exudative, proliferative and fibrotic phases: fibrosis and traction bronchiectasis appear after one to two weeks.
- Cardiogenic oedema is the main alternative: cardiomegaly, septal lines and effusions favour it.
Acquire the study
- Portable supine AP chest radiograph daily in ICU; CT chest when complications or an alternative cause are suspected.
The manoeuvre
- AP supine radiograph: bilateral airspace opacities — extent by quadrant.
- Heart size and vascular pedicle width in cm versus cardiogenic oedema.
- Barotrauma: pneumothorax (anterior on a supine film — deep sulcus sign), pneumomediastinum.
- Tubes and lines: endotracheal tube tip in cm above the carina.
What confirms it
- Bilateral opacities within a week of a known insult, not explained by cardiac failure, with the clinical oxygenation criteria.
What licenses you to exclude it
- Clear lungs on the radiograph exclude established ARDS.
The classic misread
- Calling it ARDS when the heart is large and there are septal lines and effusions.
- Missing an anterior pneumothorax on a supine film.