Effects of alveolar recruitment maneuvers on clinical outcomes in patients with acute respiratory distress syndrome: a systematic review and meta-analysis

Purpose To assess the effects of alveolar recruitment maneuvers (ARMs) on clinical outcomes in patients with acute respiratory distress syndrome (ARDS). Methods We conducted a search of the MEDLINE, EMBASE, LILACS, CINAHL, CENTRAL, Scopus, and Web of Science (from inception to July 2014) databases for all (i.e. no language restriction) randomized controlled trials (RCTs) evaluating the effects of ARMs versus no ARMs in adults with ARDS. Four teams of two reviewers independently assessed the eligibility of the studies identified during the search and appraised the risk of bias and extracted data from those which were assessed as meeting the inclusion criteria. Data were pooled using the random-effects model. Trial sequential analysis (TSA) was used to establish monitoring boundaries to limit global type I error due to repetitive testing for our primary outcome (in-hospital mortality). The GRADE system was used to rate the quality of evidence. Results Our database search identified ten RCTs (1,594 patients, 612 events) which satisfied the inclusion criteria. The meta-analysis assessing the effect of ARMs on in-hospital mortality showed a risk ratio (RR) of 0.84 [95 % confidence interval (CI) 0.74–0.95; I 2 = 0 %], although the quality of evidence was considered to be low due to the risk of bias in the included trials and the indirectness of the evidence—that is, ARMs were usually conducted together with other ventilatory interventions which may affect the outcome of interest. There were no differences in the rates of barotrauma (RR 1.11; 95 % CI 0.78–1.57; I 2 = 0 %) or need for rescue therapies (RR 0.76, 95 % CI 0.41–1.40; I 2 = 56 %). Most trials found no difference between groups in terms of duration of mechanical ventilation and length of stay in the intensive care unit and hospital. The TSA showed that the available evidence for the effect of ARMs on in-hospital mortality is precise in the case of a type I error of 5 %, but it is not precise with a type I error of 1 %. Conclusions Although ARMs may decrease the mortality of patients with ARDS without increasing the risk for major adverse events, current evidence is not definitive. Large-scale ongoing trials addressing this question may provide data better applicable to clinical practice.