There have been multiple conflicting RCTs but the weight of evidence now suggests prone ventilation is beneficial in selected severe ARDS patients. Gattinoni et al 2001 was the original study showing improvement in oxygenation of most patients with ALI /ARDS by proning. The PROSEVA trial by Guerin et al 2013 showed a marked mortality benefit (NNT = 6) for prone ventilation in severe ARDS (28-day mortality 16% prone versus 32.8% supine).
