When should chest compressions be paused to analyze the cardiac rhythm? A systematic review and meta-analysis.

OBJECTIVES: 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). CONCLUSION: 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.