Prone position

Abstract

Prone position can prevent ventilator-induced lung injury in acute respiratory distress syndrome (ARDS) patients receiving conventional mechanical ventilation and, hence, may have the potential to improve survival from this basis. Even though no single randomized controlled trial has proven benefit on patient outcome until recently, two meta-analyses, one on grouped data and the other on individual data, have shown that patients with PaO2/FIO2 ratio less than 100 mmHg at the time of inclusion did benefit from prone position. As a fifth trial completed recently has shown a significant reduction in mortality in patients with severe and confirmed ARDS from using prone position, the purpose of this review is to revisit prone positioning in ARDS in the light of these new findings. In this trial done in patients with severe ARDS severity criteria (PaO2/FIO2 ratio less than 150 mmHg with positive end expiratory pressure of 5 cmH2O or more, FIO2 of 60% or more and tidal volume around 6 ml/kg predicted body weight) confirmed 12-24 h after the onset of ARDS, the day 28 mortality in the supine group (229 patients) was 32.8 versus 16% in the prone group (237 patients) (P < 0.001). Significant reduction in mortality was confirmed at day 90. From the combined results of the two meta-analyses and the last randomized controlled trial, there is a very strong signal to use prone position in patients with severe ARDS, as early as possible and for long sessions.