title: Chest compressions before defibrillation for out-of-hospital cardiac arrest: a meta-analysis of randomized controlled clinical trials.
abstract: BACKGROUND
  Current 2005 guidelines for advanced cardiac life support strongly recommend immediate defibrillation for out-of-hospital cardiac arrest. However, findings from experimental and clinical studies have indicated a potential advantage of pretreatment with chest compression-only cardiopulmonary resuscitation (CPR) prior to defibrillation in improving outcomes. The aim of this meta-analysis is to evaluate the beneficial effect of chest compression-first versus defibrillation-first on survival in patients with out-of-hospital cardiac arrest.
  
  
  METHODS
  Main outcome measures were survival to hospital discharge (primary endpoint), return of spontaneous circulation (ROSC), neurologic outcome and long-term survival. Randomized, controlled clinical trials that were published between January 1, 1950, and June 19, 2010, were identified by a computerized search using SCOPUS, MEDLINE, BIOS, EMBASE, the Cochrane Central Register of Controlled Trials, International Pharmaceutical Abstracts database, and Web of Science and supplemented by conference proceedings. Random effects models were used to calculate pooled odds ratios (ORs). A subgroup analysis was conducted to explore the effects of response interval greater than 5 min on outcomes.
  
  
  RESULTS
  A total of four trials enrolling 1503 subjects were integrated into this analysis. No difference was found between chest compression-first versus defibrillation-first in the rate of return of spontaneous circulation (OR 1.01 [0.82-1.26]; P = 0.979), survival to hospital discharge (OR 1.10 [0.70-1.70]; P = 0.686) or favorable neurologic outcomes (OR 1.02 [0.31-3.38]; P = 0.979). For 1-year survival, however, the OR point estimates favored chest compression first (OR 1.38 [0.95-2.02]; P = 0.092) but the 95% CI crossed 1.0, suggesting insufficient estimate precision. Similarly, for cases with prolonged response times (> 5 min) point estimates pointed toward superiority of chest compression first (OR 1.45 [0.66-3.20]; P = 0.353), but the 95% CI again crossed 1.0.
  
  
  CONCLUSIONS
  Current evidence does not support the notion that chest compression first prior to defibrillation improves the outcome of patients in out-of-hospital cardiac arrest. It appears that both treatments are equivalent. However, subgroup analyses indicate that chest compression first may be beneficial for cardiac arrests with a prolonged response time.
authors.affiliation: University of Michigan Medical Center, Cardiovascular Medicine, Ann Arbor, Michigan, USA. pascalmeier74@gmail.com
authors.forename: Pascal
authors.initials: P
authors.lastname: Meier
authors.forename: Paul
authors.initials: P
authors.lastname: Baker
authors.forename: Daniel
authors.initials: D
authors.lastname: Jost
authors.forename: Ian
authors.initials: I
authors.lastname: Jacobs
authors.forename: Bettina
authors.initials: B
authors.lastname: Henzi
authors.forename: Guido
authors.initials: G
authors.lastname: Knapp
authors.forename: Comilla
authors.initials: C
authors.lastname: Sasson
mesh_terms: D016887:Cardiopulmonary Resuscitation / Q000592:standards*; D004554:Electric Countershock; D004632:Emergency Medical Services / Q000379:methods*; D006336:Heart Massage / Q000592:standards*; D006801:Humans; D016017:Odds Ratio; D058687:Out-of-Hospital Cardiac Arrest / Q000401:mortality* / Q000628:therapy*; D017410:Practice Guidelines as Topic; D016032:Randomized Controlled Trials as Topic; D013534:Survival; D013997:Time Factors; D016896:Treatment Outcome