Sufficient data exist to establish the oxygenation benefit of prone positioning for most patients with acute lung injury, although no improvement in mortality was noted in the largest trials to date . Preferential use of prone positioning in all ALI/ARDS patients cannot currently be recommended due to a degree of inconvenience associated with its use and the lack of data showing an influence on overall outcomes. However, since the risks of prone positioning when properly performed are minimal, we recommend its early use in patients failing to respond to high pressure recruitment maneuvers and who require PEEP >12 cmH2O and an FiO2 >0.60.

Duration — The optimal duration of prone positioning is unknown. While many studies have used repeated sessions of prone positioning lasting approximately six to eight hours per day, impressive and persistent improvements in oxygenation have been noted with prone positioning of longer duration (20 horas/dia)