title: Effects of alveolar recruitment maneuvers on clinical outcomes in patients with acute respiratory distress syndrome: a systematic review and meta-analysis.
abstract: OBJECTIVE
  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.
authors.affiliation: Research Institute of the Hospital do Coração (Heart Hospital)-IEP/HCor, Rua Abílio Soares 250, No. 12 andar, 04005-000, São Paulo, SP, Brazil, esuzumura@yahoo.com.br.
authors.forename: Erica Aranha
authors.initials: EA
authors.lastname: Suzumura
authors.forename: Mabel
authors.initials: M
authors.lastname: Figueiró
authors.forename: Karina
authors.initials: K
authors.lastname: Normilio-Silva
authors.forename: Lígia
authors.initials: L
authors.lastname: Laranjeira
authors.forename: Claudia
authors.initials: C
authors.lastname: Oliveira
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: Buehler
authors.forename: Diogo
authors.initials: D
authors.lastname: Bugano
authors.forename: Marcelo Britto
authors.initials: MB
authors.lastname: Passos Amato
authors.forename: Carlos Roberto
authors.initials: CR
authors.lastname: Ribeiro Carvalho
authors.forename: Otavio
authors.initials: O
authors.lastname: Berwanger
authors.forename: Alexandre Biasi
authors.initials: AB
authors.lastname: Cavalcanti
mesh_terms: D017052:Hospital Mortality; D006801:Humans; D011650:Pulmonary Alveoli; D012128:Respiratory Distress Syndrome / Q000628:therapy*; D012138:Respiratory Therapy; D016896:Treatment Outcome
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