Effect of prone positioning in patients with acute respiratory distress syndrome: a meta-analysis

To review the effectiveness of prone position as compared with supine position, with respect to mortality, improvement in oxygenation, number of days on mechanical ventilation, and ventilator-associated pneumonia.

PubMed, EMBASE, Cochrane database, and a manual review of article bibliographies.

Randomized controlled trials comparing > or = 6 hrs of prone position with supine position in adult patients with adult respiratory distress syndrome.

Two reviewers independently performed assessment of abstracts and study quality. Data were combined in a meta-analysis using random-effect models.

Five studies were identified. We did not find any significant differences in intensive care unit mortality (three studies, 466 patients; odds ratio, 0.79; 95% confidence interval [CI], 0.45-1.39), 28- to 30-day mortality (three studies, 1,231 patients; odds ratio, 0.95; 95% CI, 0.71-1.28), and 90-day mortality (four studies, 1,271 patients; odds ratio, 0.99; 95% CI, 0.77-1.27). However, prone position showed significant reduction in mortality in patients with higher illness severity (two studies, 113 patients; odds ratio, 0.29; 95% CI, 0.12-0.70). Prone positioning also showed significant and persistent improvement in the PaO2/FiO2 ratio in early (12 hrs to 2 days) (four studies, 866 patients; weighted mean difference, 51.5; 95% CI, 6.95-96.05), intermediate (4 days) (three studies, 754 patients; weighted mean difference, 43.87; 95% CI, 13.86-73.88), and late (10 days) period (four studies, 833 patients; weighted mean difference, 24.89; 95% CI, 15.3-34.48). There were no significant differences in number of days on mechanical ventilation (two studies, 831 patients; weighted mean difference, -0.42 days; 95% CI, -1.56 to 0.72) or incidence of ventilator-associated pneumonia (three studies, 967 patients; weighted mean difference, 0.78%; 95% CI, 0.40-1.51).

Based on the results of this meta-analysis, prone position improves oxygenation in patients with adult respiratory distress syndrome, and in patients with higher illness severity, it also may reduce mortality.