Prone positioning has been in existence since 1974; however, the equipment and technique has now been refined and has proven to decrease mortality in severe ARDS. Prone positioning decreases the amount of alveolar collapse and decreases V/Q mismatching in patients with severe ARDS.
The first large study to show significant mortality benefit was a study of nearly 450 patients with severe ARDS which demonstrated over 50% decreased 30-day and 90-day mortality compared with standard lung-protective ventilation.
A second meta-analysis confirmed that prone ventilation was superior to conventional lung-protective ventilation in severe ARDS.  The meta-analysis showed the following:
- Reduced mortality (RR 0.74)
- NNT to save one life was 11
- Mortality was only decreased if the duration of prone positioning was at least 16 hours/day
Intubated patient with severe ARDS