The Efficacy and Safety of Prone Positional Ventilation in Acute Respiratory Distress Syndrome

Updated Study-Level Meta-analysis of 11 Randomized Controlled Trials

Joo Myung Lee, MD, MPH; Won Bae, MD; Yeon Joo Lee, MD; Young-Jae Cho, MD, MPH

Disclosures

Crit Care Med. 2014;42(5):1252-1262. 

In This Article

Abstract and Introduction

Abstract

Objective: The survival benefit of prone positioning during mechanical ventilation for acute respiratory distress syndrome has been a matter of debate. Recent multicenter randomized controlled trials have shown a significant reduction of 28-day and 90-day mortality associated with prone positioning during mechanical ventilation for severe acute respiratory distress syndrome. We performed an up-to-date meta-analysis on this topic and elucidated the effect of prone positioning on overall mortality and associated complications.

Data Sources: PubMed, EMBASE, BioMed Central, Cochrane Central Register of Controlled Trials, ClinicalTrials.gov, and conference proceedings through May 2013.

Study Selection: Randomized controlled trial comparing overall mortality of prone-versus-supine positioning in patients with acute respiratory distress syndrome.

Data Extraction: Data were extracted for populations, interventions, outcomes, and risk of bias. The prespecified primary endpoint was overall mortality, using the longest available follow-up in each study. The odds ratio with 95% CI was the effect measure.

Data Synthesis: This analysis included 11 randomized controlled trial, 2,246 total adult patients, and 1,142 patients ventilated in the prone position. Prone positioning during ventilation significantly reduced overall mortality in the random-effect model (odds ratio, 0.77; 95% CI, 0.59–0.99; p = 0.039; I 2 = 33.7%), and the effects were marked in the subgroup in which the duration of prone positioning was more than 10 hr/session, compared with the subgroup with a short-term duration of prone positioning (odds ratio, 0.62; 9% CI, 0.48–0.79; p = 0.039; p interaction = 0.015). Prone positioning was significantly associated with pressure ulcers (odds ratio, 1.49; 95% CI, 1.18–1.89; p = 0.001; I 2 = 0.0%) and major airway problems (odds ratio, 1.55; 95% CI, 1.10–2.17; p = 0.012; I 2 = 32.7%).

Conclusions: Ventilation in the prone position significantly reduced overall mortality in patients with severe acute respiratory distress syndrome. Sufficient duration of prone positioning was significantly associated with a reduction in overall mortality. Prone ventilation was also significantly associated with pressure ulcers and major airway problems.

Introduction

Prone positioning during mechanical ventilation for acute respiratory distress syndrome (ARDS) has a robust scientific background. Previous randomized controlled trials (RCTs) have demonstrated that prone positioning results in a significant improvement of oxygenation in patients with acute hypoxemic respiratory failure, as measured by the ratio of PaO2 to the FIO2.[1–3] Despite these physiologic benefits, several RCTs reported no improvement of patient survival with prone positioning.[1,2,4,5] However, post hoc analysis of the first RCT carried out by Gattinoni et al,[1] which compared prone and supine ventilation in patient with acute respiratory failure, demonstrated that prone positioning reduced mortality by 10 days in the subgroup of patients with the highest disease severity (Simplified Acute Physiology Score [SAPS II] ≥ 50). Furthermore, selected meta-analyses, which included the severest subgroup of patients (by SAPS II score or PaO2/FIO2 < 100 mm Hg), revealed similar findings.[6–8] A recently published multicenter trial by Guérin et al[9] showed significant mortality reduction associated with prone positioning for patients with severe ARDS, as defined by PaO 2/FIO 2 less than or equal to 150 mm Hg with positive end-expiratory pressure (PEEP) more than or equal to 5 cm H2O.

We performed a systematic review and comprehensive meta-analysis of RCTs to compare the efficacy (reduction of overall mortality) and safety (adverse events) of prone versus supine positioning during mechanical ventilation for ARDS. We also evaluated a chronological trend of pooled estimates of prone positioning by cumulative meta-analysis and the effect of strength of the intervention (i.e., actual duration of prone positioning) to the pooled estimates by meta-regression.

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