Abstract 220: Association Between Initial Defibrillator Pad Position And Outcomes For Out-of-hospital Cardiac Arrest Patients Presenting With Shockable Rhythms

Abstract

Background: Ventricular fibrillation (VF) or ventricular tachycardia (VT) are the most treatable causes of out-of-hospital cardiac arrest (OHCA). Yet, it remains unknown if defibrillator pad position, placement in the anterior-posterior (AP) or anterior-lateral (AL) positions, impacts patient outcomes in VF/VT OHCA. Aim: Evaluate the association between initial defibrillator pad placement (AP vs. AL) and OHCA outcomes for patients presenting with VF/VT. Methods: This was a prospective observational study of non-traumatic OHCA patients with initial VF/VT on EMS rhythm analysis treated by a single EMS agency in the Portland Cardiac Arrest Epidemiologic Registry (PDX Epistry) from July 1st, 2019 through October 15th, 2022. Our primary outcome was return of spontaneous circulation (ROSC) at any time and secondary outcomes were ROSC at emergency department (ED) arrival, survival to admission, survival to discharge, and functional survival (cerebral perfusion category score of ≤2). We performed t-tests, chi-squared tests, and multivariable logistic regressions adjusting for age, sex, witness status, bystander interventions, arrest location, 911 call to EMS arrival time, and year of arrest. Results: A total of 243 OHCA patients met inclusion criteria and 232 (95.5%) had initial pad positioning documented (133 AP and 99 AL). Patients with AP placement had higher rates of ROSC at any time (72.2% vs. 47.5%, p<0.001), survival to admission (56.4% vs. 41.4%, p=0.024), survival to discharge (36.1% vs. 24.2%, p=0.050), and functional survival (36.1% vs. 21.2%, p=0.012) compared to AL, with no difference for ROSC at ED arrival (52.6% vs. 40.4%, p=0.065). AP versus AL placement showed higher adjusted odds (aOR [95% CI]) for ROSC at any time (2.76 [1.55-4.93]) and functional survival (2.06 [1.05-4.05]), but not ROSC at ED arrival (1.50, [0.85-2.64]), survival to admission (1.69 [0.96-2.96]) or survival to discharge (1.68 [0.86-3.27]). Among patients with ROSC at ED arrival, patients with AP placement, had shorter times from 911 call to sustained ROSC (21.0 vs. 28.4 min, p=0.013). Conclusions: Initial AP pad placement, compared to AL, was associated with higher ROSC, a reduction in time to sustained ROSC, and higher functional survival for patients with VF/VT OHCA.