Abstract 106: Increasing CPR during Out-of-hospital Ventricular Fibrillation Arrest: Survival Implications of Guideline Changes
Background: The most recent resuscitation guidelines have sought to improve the interface between defibrillation and CPR. However, the survival implications of these changes are unknown. A year prior to issuance of the most recent guidelines, the EMS of the study community implemented protocol changes that provided a single shock without rhythm reanalysis, stacked shocks, or post-defibrillation pulse checks, while extending the period of CPR from 1 to 2 minutes. We hypothesized survival would be better in patients treated with the new protocol.
Methods: The study took place in a community with a two-tiered EMS response and an established system of cardiac arrest surveillance, training, and review. Per the Utstein template, the investigation was a cohort study of persons suffering bystander-witnessed, out-of-hospital ventricular fibrillation arrest due to heart disease that compared a prospectively-defined intervention group (January 1, 2005–January 31, 2006) with a historical control group that was treated with the prior guideline approach of rhythm reanalysis, stacked shocks, and post-defibrillation pulse checks (January 1, 2002–December 31, 2004). In fall of 2004, EMTs were trained regarding the new protocol and AEDs were reprogrammed. The primary outcome was survival to hospital discharge. Logistic regression was used to assess the association between survival and study period while accounting for potential confounders.
Results: The proportion of all treated arrests meeting inclusion criteria was similar for intervention and control periods (15.4% 134/869 versus 16.6% 374/2255). Survival to hospital discharge was greater during the intervention compared to control period (46% 61/134 versus 33% 122/374, p=0.008). Adjustment for covariates did not alter the association. Better hospital survival during the intervention period corresponded to a greater proportion with return of circulation at the end of EMS care (74% 99/134 versus 60% 223/374) as well as a decrease in the interval from initial shock to start of CPR (7 seconds versus 28 seconds) based on electronic AED record review.
Conclusion: These results suggest the new guideline approach will alter the interface between defibrillation and CPR and in turn may improve outcome.