Prone positioning reduces mortality from acute respiratory distress syndrome in the low tidal volume era: a meta-analysis

Abstract

Purpose Prone positioning for ARDS has been performed for decades without definitive evidence of clinical benefit. A recent multicenter trial demonstrated for the first time significantly reduced mortality with prone positioning. This meta-analysis was performed to integrate these findings with existing literature and test whether differences in tidal volume explain conflicting results among randomized trials. Methods Studies were identified using MEDLINE, EMBASE, Cochrane Register of Controlled Trials, LILACS, and citation review. Included were randomized trials evaluating the effect on mortality of prone versus supine positioning during conventional ventilation for ARDS. The primary outcome was risk ratio of death at 60 days meta-analyzed using random effects models. Analysis stratified by high (>8 ml/kg predicted body weight) or low (≤8 ml/kg PBW) mean baseline tidal volume was planned a priori. Results Seven trials were identified including 2,119 patients, of whom 1,088 received prone positioning. Overall, prone positioning was not significantly associated with the risk ratio of death (RR 0.83; 95 % CI 0.68–1.02; p = 0.073; I2 = 64 %). When stratified by high or low tidal volume, prone positioning was associated with a significant decrease in RR of death only among studies with low baseline tidal volume (RR 0.66; 95 % CI 0.50–0.86; p = 0.002; I2 = 25 %). Stratification by tidal volume explained over half the between-study heterogeneity observed in the unstratified analysis. Conclusions Prone positioning is associated with significantly reduced mortality from ARDS in the low tidal volume era. Substantial heterogeneity across studies can be explained by differences in tidal volume.

Surviving Sepsis Campaign: International Guidelines for Management of Sepsis and Septic Shock: 2016

“…Meta-analysis including this study demonstrated reduced mortality in patients treated with prone compared with supine position (RR 0.85; 95% CI 0.71-1.01) as well as improved oxygenation as measured by change in Pao 2 /Fio 2 ratio (median 24.03 higher, 95% CI 13.3-34.7 higher) [375]. Most patients respond to the prone position with improved oxygenation and may also have improved lung compliance [374,[376][377][378][379].…”

“…While prone position may be associated with potentially life-threatening complications including accidental removal of the endotracheal tube, this was not evident in pooled analysis (RR 1.09; 95% CI 0.85-1.39). However, prone position was associated with an increase in pressure sores (RR 1.37; 95% CI 1.05-1.79) [375], and some patients have contraindications to the prone position [374].…”

Recruitment Maneuvers and PEEP Titration

“…Thus, prone positioning might be considered a recruitment maneuver. 46 One randomized controlled trial 47 and several meta-analyses report a survival benefit for prone position, 48,49 particularly in severe ARDS. 43 …”

Should Early Prone Positioning Be a Standard of Care in ARDS With Refractory Hypoxemia?

“…Below the timeline are other important trials and meta-analyses in ARDS. 3,4,7,9,18,21,22 PP ϭ prone positioning, LPV ϭ lungprotective ventilation, NR ϭ not reported, NMB ϭ neuromuscular blockade, RR ϭ relative risk, RCT ϭ randomized controlled trial. *, reported only as a complication as a percentage of subjects who needed increased sedation/muscle relaxants after protocol initiation.…”