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Crit Care Med. 2008 Feb;36(2):603-9. doi: 10.1097/01.CCM.0000299739.98236.05.

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

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Division of Critical Care, Department of Medicine, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada.



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.

[Indexed for MEDLINE]

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