title: When should chest compressions be paused to analyze the cardiac rhythm? A systematic review and meta-analysis.
abstract: OBJECTIVE
  Most guidelines recommend pausing chest compressions at 2 min intervals to analyze the cardiac rhythm. We conducted a systematic review and meta-analysis to define the optimal interval at which to pause chest compressions in adults for cardiac rhythm analysis in any setting.
  
  
  METHODS
  We searched PubMed, Embase, and Cochrane databases through January 2, 2015, including human studies addressing any two different intervals of rhythm analysis. GRADE (Grades of Recommendation, Assessment, Development, and Evaluation) methodology evaluated confidence in estimates of effect for evidence pertaining to functional outcome, survival, and return of spontaneous circulation.
  
  
  RESULTS
  Of 1,136 identified papers, nine were included (three RCTs and six observational studies). Quality of evidence for each outcome was very low or low (usually downgraded risk of bias and indirectness). RCTs comparing specific intervals (3 min vs. immediate rhythm analysis; 1 vs. 2 min; 3 vs. 1 min) demonstrated no difference between either arm. Meta-analyses of observational studies demonstrated benefit for a bundled 'minimally interrupted chest compression' protocol dictating 200-compression intervals compared with historical controls treated with 1- or 3 min intervals per the 2000 guidelines (OR 1.85, 95% CI 1.27,2.68 for ROSC; OR 2.84, 95% CI 2.12,3.79 for survival to discharge; OR 2.94, 95% CI 1.60, 5.37 for good functional outcome).
  
  
  CONCLUSIONS
  There is a paucity of quality evidence to support pausing chest compressions at any singular interval to assess the cardiac rhythm in adults in cardiac arrest in any setting. Very low-quality evidence suggests improved clinical outcomes in patients receiving 200-compression intervals compared with 1- or 3 min intervals.
authors.affiliation: Department of Emergency Medicine, Michigan State University College of Human Medicine, 15 Michigan Street NE, Suite 420 Secchia Center, Grand Rapids, MI, 49503, United States. Electronic address: reyno406@msu.edu.
authors.forename: Joshua C
authors.initials: JC
authors.lastname: Reynolds
authors.affiliation: Department of Emergency Medicine, Municipal Institute for Emergency Medicine Novi Sad, AP Vojvodina, Serbia.
authors.forename: Violetta
authors.initials: V
authors.lastname: Raffay
authors.affiliation: University of Calgary, Calgary, Alberta, Canada.
authors.forename: Eddy
authors.initials: E
authors.lastname: Lang
authors.affiliation: Royal Melbourne Hospital Clinical School, University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Peter T
authors.initials: PT
authors.lastname: Morley
authors.affiliation: NZRN, New Zealand Resuscitation Council, Wellington, New Zealand.
authors.forename: Kevin
authors.initials: K
authors.lastname: Nation
mesh_terms: D016887:Cardiopulmonary Resuscitation / Q000379:methods*; D006339:Heart Rate; D006801:Humans; D013997:Time Factors
keywords: Basic life support; Cardiac arrest; Cardiac rhythm; Cardiopulmonary resuscitation; Chest compressions; Meta-analysis; Systematic review