Abstract 132: Neurological Favorable Outcome Associated With Number of Prehospital Defibrillation Attempts in Out-of-Hospital Cardiac Arrest Without Return of Spontaneous Circulation on Scene

Abstract

Background: The early and timely defibrillation in shockable rhythm of out-of-hospital cardiac arrest (OHCA) by prehospital EMS providers is crucial for successful resuscitation. In emergency medical service (EMS) system, where advanced cardiac life support could not be fully provided before hospital transport, optimal range of prehospital defibrillation attempts is debatable. We evaluated association between number of prehospital defibrillation attempts and survival outcomes in OHCA patients who were unresponsive to field resuscitation and defibrillations. Methods: This is a retrospective observational study using nationwide OHCA registry of Korea from 2013 to 2016. Adult EMS treated OHCA with presumed cardiac origin with shockable initial ECG rhythm were enrolled. Final analysis was performed in patients who did not achieve return of spontaneous circulation (ROSC) on scene before hospital transport. We categorized number of prehospital defibrillation attempt into 3 groups: ≤3 attempts, 4-5 attempts and ≥6 attempts. Primary outcome was favorable neurological outcome at hospital discharge. Multivariable logistic regression modeling was used to evaluate association between neurological outcome and defibrillation attempts. Result: Total 6,679 patients were enrolled for final analyzed. Among total ≤3 defibrillations were attempted in 5015 patients (75.1%), 1050 patients (15.7%) for 4-5 attempts, 614 patient. (9.2%) for ≥6 attempts. Although survival to discharge rate was highest in group with ≤3 defibrillation attempts (8.1% vs. 7.0% vs. 2.9%, p<0.01), survival rate with favorable neurological outcome was highest in group with 4-5 defibrillation attempts (3.0% vs. 4.5% vs. 2.1%, p=0.02). As 4-5 attempts group reference, adjusted odds ratio for favorable neurological outcome of ≤3 attempts was 0.66 (95% CI 0.46 - 0.94) and of ≥6 attempts was 0.47 (95% CI 0.25 - 0.89). Conclusion: For patients with shockable initial cardiac rhythm who were unresponsive to filed defibrillation and resuscitation, moderate amount of defibrillation attempt was associated with favorable neurological outcome compared to fewer defibrillation attempts and prolonged number of defibrillation attempts on scene.