Chest-compression-only versus standard cardiopulmonary resuscitation: a meta-analysis

Background Evidence suggests that dispatcher-assisted chest compression-only bystander CPR may be superior to standard CPR (chest compressions and rescue ventilation) in out-of-hospital cardiac arrest, yet recent clinical trials did not observe improved outcomes. The goal of the study was to determine the association between chest compression-only CPR and survival after out-of-hospital cardiac arrest. Methods Studies published until August 2010 were systematically searched and identified in MEDLINE and EMBASE databases. For the primary meta-analysis only clinical trials were included that prospectively randomized dispatcher instructions to chest compression-only versus standard bystander CPR in out-of-hospital adult cardiac arrest patients; for the secondary meta-analysis observational cohort studies were included that distinguished between standard CPR and chest compression-only CPR. All studies were required to contain survival data. Data on study characteristics, methods and outcomes (return of spontaneous circulation, survival to discharge, 30-day survival, and favourable neurologic outcome) were extracted. A fixed-effects model was used for both meta-analyses for lack of heterogeneity among the studies (I2 0%). Findings All three published randomized clinical trials were included in the meta-analysis. The pooled analyses shows that dispatcher-assisted chest compression-only bystander CPR for adult out-of-hospital cardiac arrest was associated with a 22% improved chance of survival (risk ratio [RR] 1.22 [95% confidence interval {CI}, 1.01 – 1.47]; I2, 0%) compared to standard CPR. The absolute increase in survival was 2.4%; the number needed to treat was 41. The secondary meta-analysis included seven observational studies of bystander-CPR (not dispatcher-assisted) and showed no difference between the two CPR techniques (RR, 0.96 [95% CI, 0.83 – 1.11]; I2, 0%). Interpretation Dispatcher-assisted chest compression-only bystander CPR is associated with improved survival in adult patients after out-of-hospital cardiac arrest compared to standard CPR.