LO70: Do automatic external defibrillators improve rates of return of spontaneous circulation, survival to hospital discharge and favourable neurological survival in Canada?

Abstract

Introduction: Survival for victims of out-of-hospital cardiac arrest (OHCA) is typically 8-12%. Recent evidence has shown that public access automatic external defibrillators (AED) may improve survival. The objectives of this study were to determine whether AEDs improve rates of return of spontaneous circulation (ROSC), overall survival, and favourable neurological survival (FNS) in Canada. Methods: The BC Resuscitation Outcomes Consortium prospectively collected detailed prehospital and hospital data on consecutive non-traumatic OHCAs from 2011-2015 within BC’s four metropolitan areas. We included all EMS-treated adult patients. Data were collected in accordance with recognized Utstein criteria. We described frequencies with counts, means and medians where appropriate, and the Z-test was used to compare population proportions. Results: We examined 7577 OHCAs from 2011-2015. AEDs were deployed on 223 patients in this period (mean age 60.4 yrs [95% CI 45.7-75.1] and 83.9% male; non-AED OHCAs mean age 66.2 yrs [48.4-83.8] and 67.3% male). Seventy seven percent of AED deployments occurred in public locations, 69.1% were witnessed by bystanders and CPR was initiated in 98.7% of these cases. Fifteen percent of non-AED OHCAs occurred in public locations, 38.3% were bystander witnessed, and 45.4% received bystander CPR. AEDs delivered shocks to 61.4% of patients, and EMS crews found an initial shockable rhythm upon scene arrival in 60.5% of AED deployments (22.9% for non-AED cases). AED OHCA patients had higher rates of ROSC at any time (67.2% vs 47.6%; difference of 19.6% [12.9-26.2 p<0.01]), and ROSC at ED arrival (61% vs 35.4%; difference of 25.6% [19.2-32.0 p<0.01]). AED OHCA patients had higher rates of survival to hospital discharge (23.8% vs 8.5%; difference 15.3% [11.5-19.1 p<0.01]). Detailed neurologic outcome data was not available for all patients, yet for those which it was available AED OHCA patients had improved outcomes (modified Rankin score<2) compared to non-AED OHCA patients (9.0% vs 5.4%; difference 3.6% [0.6-6.6 p<0.02]. Conclusion: Automatic external defibrillators markedly improve rates of ROSC at any time, sustained ROSC at ED arrival, survival to hospital discharge, and FNS in Canada. Continued support for public access AED programs is essential to improve patient outcomes.