The effect of prone positioning in acute respiratory distress syndrome or acute lung injury: a meta-analysis. Areas of uncertainty and recommendations for research.
OBJECTIVE
To compare the effects of ventilation in prone and in supine position in patients with acute lung injury/acute respiratory distress syndrome (ALI/ARDS).


METHODS
Meta-analysis of randomised controlled trials.


METHODS
BioMedCentral, PubMed, CINAHL, and Embase (to November 2007), with additional information from authors.


RESULTS
From selected randomised controlled trials comparing positioning in ALI/ARDS we extracted data concerning study design, disease severity, clinical outcomes, and adverse events. Five trials including 1,372 patients met the inclusion criteria for mortality analysis; one trial was added to assess the effects on acquisition of ventilator-associated pneumonia (VAP). The included trials were significantly underpowered and enrolled patients with varying severity. Prone positioning duration and mechanical ventilation strategy were not standardised across studies. Using a fixed-effects model, we did not find a significant effect of prone positioning (proning) on mortality (odds ratio 0.97, 95% confidence interval 0.77-1.22). The PaO(2)/FiO(2) ratio increased significantly more with proning (weighted means difference 25 mmHg, p < 0.00001). Proning was associated with a non-significant 23% reduction in the odds of VAP (p=0.09), and with no increase in major adverse airway complications: OR 1.01, 95% CI 0.71-1.43. Length of intensive care unit stay was marginally and not significantly increased by proning.


CONCLUSIONS
Prone position is not associated with a significant reduction in mortality from ALI/ARDS despite a significant increase in PaO(2)/FiO(2), is safe, and tends to decrease VAP. Published studies exhibit substantial clinical heterogeneity, suggesting that an adequately sized study optimising the duration of proning and ventilation strategy is warranted to enable definitive conclusions to be drawn.
Abroug
Fekri
F
Service de Réanimation Polyvalente, CHU F. Bourguiba, 5000 Monastir, Tunisia. f.abroug@rns.tn
Ouanes-Besbes
Lamia
L
Elatrous
Souheil
S
Brochard
Laurent
L
D055371:Acute Lung Injury / Q000401:mortality / Q000503:physiopathology*; D003627:Data Interpretation, Statistical; D006801:Humans; D007362:Intensive Care Units; D016684:Prone Position / Q000502:physiology*; D016032:Randomized Controlled Trials as Topic; D012121:Respiration, Artificial / Q000379:methods; D012128:Respiratory Distress Syndrome / Q000401:mortality / Q000503:physiopathology*