Biphasic Defibrillation Does not Improve Outcomes Compared to Monophasic Defibrillation in Out-of-Hospital Cardiac Arrest

Study Objective. To compare the outcomes of out-of hospital cardiac arrest (OHCA) victims treated with monophasic truncated exponential (MTE) versus biphasic truncated exponential (BTE) defibrillation in an urban EMS system. Methods. We conducted a retrospective review of electronic prehospital andhospital records for victims of OHCA between August 2000 andJuly 2004, including two years before andafter implementation of biphasic defibrillators by the Fresno County EMS agency. Main outcome measures included: return of spontaneous circulation (ROSC), number of defibrillations required for ROSC, survival to hospital discharge, anddischarge to home versus an extended care facility. Results. There were 485 cases of cardiac arrest included. Baseline characteristics between the monophasic andbiphasic groups were similar. ROSC was achieved in 77 (30.6%, 95% CI 25.2–36.5%) of 252 patients in the monophasic group, andin 70 (30.0% 95% CI 24.5–36.2%) of 233 in the biphasic group (p =. 92). Survival to hospital discharge was 12.3% (95% CI 8.8–17%) for monophasic and10.3% (95% CI 7.0–14.9%) for biphasic (p =. 57). Discharge to home was accomplished in 20 (7.9%, 95% CI 5.1–12.0%) of the monophasic, andin 15 (6.4%, 95% CI 3.9–10.4%) of the biphasic group (p =. 60). More defibrillations were required to achieve ROSC (3.5 vs. 2.6, p =. 015) in the monophasic group. Conclusions. We found no difference in ROSC or survival to hospital discharge between MTE andBTE defibrillation in the treatment of OHCA, although fewer defibrillations were required to achieve ROSC in those treated with biphasic defibrillation.