The goal of the Prone-Supine II Study was to evaluate possible outcome benefits of prone positioning in patients with ARDS and moderate or severe hypoxemia. From February 2004 through June 2008, a total of 342 adults with ARDS receiving mechanical ventilation at 23 centers in Italy and 2 in Spain were enrolled and prospectively stratified into subgroups with moderate (n = 192) and severe (n = 150) hypoxemia. Participants were randomly selected to supine positioning (n = 174) or prone positioning (20 hours per day; n = 168) during ventilation.
The main endpoint of the study was 28-day all-cause mortality, and secondary endpoints were 6-month mortality and mortality at intensive care unit discharge, organ dysfunction, and complication rate associated with prone positioning.
For the overall entire study population, prone and supine positioning were associated with similar mortality rates at 28 days and at 6 months. However, the prone group had a significantly higher complication rate. Positioning was not associated with any apparent differences in median Sequential Organ Failure Assessment (SOFA) scores, ventilator-free days, or intensive care unit length of stay.
According to the authors, Â “data from this study indicate that prone positioning does not provide significant survival benefit in patients with ARDS or in subgroups of patients with moderate and severe hypoxemia. However, its potential role in patients with the most severe hypoxemia, for whom the possible benefit could outweigh the risk of complications, must be further investigated, considering the strong pathophysiological background, the post hoc result of our previous study, the most recent meta-analysis, and the favorable trend observed prospectively in this study.”