Abstract 254: High Shock Efficacy and Algorithm Performance for a 150J Biphasic Waveform AED Used by Lay and BLS Responders During Out-of-hospital Cardiac Arrest

Abstract

Introduction: Effective AED defibrillation of out of hospital cardiac arrest (OHCA) depends on the safe and effective identification of shockable rhythms, and on delivery of effective defibrillation energy. This report summarizes rhythm detection performance and shock efficacy during OHCA uses of Philips HeartStart Home and OnSite AEDs using non-escalating 150 J therapy. Methods: A convenience sample of 185 OHCA AED patient uses were reviewed by clinical experts. All analysis periods that resulted in AED rhythm advisories (Shock Advised or No Shock Advised) were annotated. Shockable rhythm categories include VF and polymorphic VT/flutter. Non-Shockable rhythm categories include normal sinus rhythm, other rhythms (e.g., atrial fibrillation/flutter, bradycardia, SVT, idioventricular, bundle branch block), and asystole. Intermediate rhythms (benefits of defibrillation are limited or uncertain) were not included. Post-shock rhythm was categorized as shockable, non-shockable, or undeterminable (rhythms corrupted by CPR artifact or pads removal within 5-s of shock delivery). Shock success was defined as conversion to a non-shockable rhythm within 5-s post-shock. Results: A total of 487 analysis periods resulted in AED rhythm advisories, with 175 annotated as Shockable and 312 Non-shockable. Sensitivity and specificity (n/N, Exact 95% CI) were 97.7% (171/175, 94.3%, 99.4%) and 100% (312/312, 98.8%, 100.0%) respectively. A total of 165 shocks were delivered to 100 patients with 5 undeterminable post-shock rhythms. The remaining 160 shocks were delivered to 156 Shockable rhythm episodes. All shock efficacy was 96.9% (155/160, 92.9%, 99.0%): 150 episodes converted to non-shockable rhythms after one shock (96.2% (150/156, 91.8%, 98.6%)); 154 after two shocks (98.7% (154/156, 95.4%, 99.8%)); and 155 after three shocks, the first two of which were undeterminable (99.4% (155/156, 96.5%, 100.0%)). The remaining episode had a failed first shock, followed by an undeterminable second shock, which was the last shock of the use. Conclusion: For these 150J fixed-energy AEDs, OHCA defibrillation is safe (100% specificity), and effective (97.7% sensitivity; 96.2% single shock effectiveness; 98.7% after two shocks; 99.4% after three shocks).