title: [Effect of 45 degree angle semirecumbent position on ventilator-associated pneumonia in mechanical ventilated patients: a  meta-analysis].
abstract: OBJECTIVE
  To systemically analyze the effect of 45 degree angle semirecumbent position on the incidence of ventilator-associated pneumonia (VAP) and other outcomes in mechanical ventilated patients, and to evaluate whether 45 degree angle semirecumbent position is superior to 25 degree angle-30 degree angle head of bed (HOB).
  
  
  METHODS
  The randomized controlled trials (RCTs) comparing the effect of different HOB on the outcomes of mechanical ventilated patients were searched (from 1st January 1990 to 20th July 2012) from five databases including the Cochrane Central Register of Controlled Trials, MEDLINE, Embase, China Knowledge Resource Integrated Database (CNKI), and Wanfang Database. Meta analysis was conducted using RevMan 5.0 software.
  
  
  RESULTS
  Data extracted from five RCTs with a total of 427 patients were analyzed. The risks of developing clinically diagnosed VAP were significantly lower among the patients in semirecumbent 45 degree angle position compared to the patients in lower position [15.96% (34/213) vs. 26.64% (57/214), relative risk (RR)=0.57, 95% confidence interval (95%CI) 0.39 to 0.83, P=0.003], while no significant differences were detected between the two groups regarding the mortality rate [27.04% (53/196) vs. 28.22% (57/202), RR=0.93, 95%CI 0.68 to 1.27, P=0.66], the length of intensive care unit (ICU) stay [weighted mean difference (WMD)=-0.45, 95%CI -1.08 to 0.18, P=0.16] and the percentage of antibiotics treatment [71.11% (32/45) vs. 60.87% (28/46), RR=1.14, 95%CI 0.85 to 1.53, P=0.37]. Two of the five trials (91 patients) were included in the sub-analysis between 45 degree angle group (45 patients) and 25 degree angle-30 degree angle group (46 patients). The results showed that comparing with 25 degree angle-30 degree angle, 45 degree angle semirecumbent position had no significance in improving patients' clinical outcomes.
  
  
  CONCLUSIONS
  This study proved that the clinically preferred semirecumbent 45 degree angle position did have effect in reducing the incidence of VAP, nevertheless, whether it's superior to 25 degree angle-30 degree angle needs to be confirmed by larger-scale, higher-quality RCTs.
authors.affiliation: Department of Critical Care Medicine, Peking University, Beijing, China.
authors.forename: Yu-xin
authors.initials: YX
authors.lastname: Leng
authors.forename: Ya-han
authors.initials: YH
authors.lastname: Song
authors.forename: Zhi-yuan
authors.initials: ZY
authors.lastname: Yao
authors.forename: Xi
authors.initials: X
authors.lastname: Zhu
mesh_terms: D006801:Humans; D007362:Intensive Care Units; D056888:Patient Positioning / Q000706:statistics & numerical data*; D053717:Pneumonia, Ventilator-Associated; D011187:Posture; D016032:Randomized Controlled Trials as Topic