Emergency vehicle intervals versus collapse-to-CPR and collapse-to-defibrillation intervals: Monitoring emergency medical services system performance in sudden cardiac arrest

Study objective: To compare emergency vehicle response intervals with collapse-to-intervention intervals to determine which of these system data better correlated with survival after prehospital sudden cardiac arrest. Study design: A 22-month case series, collected prospectively, of out-of-hospital cardiac arrests. Times of collapse, dispatch, scene arrival, CPR, and initial defibrillation were determined from dispatch records, recordings of arrest events, interviews with bystanders, and hospital records. Setting: Southwestern city (population, 400,000; area, 390 km²) with a two-tiered basic life support-advanced life support emergency medical services system. Emergency medical technician-firefighters without electrical defibrillation capability comprised the first response tier; firefighter-paramedics were the second tier. Patients: One hundred eighteen cases of witnessed, out-of-hospital cardiac arrest in adults with initial ventricular fibrillation. Main outcome measures: Survival was defined as a patient who was discharged alive from the hospital. Results: Eighteen of 118 patients (15%) survived. Survivors did not differ significantly from nonsurvivors in age, sex, or basic life support or advanced life support response intervals. Survivors had significantly (P < .05) shorter intervals from collapse to CPR (1.7 versus 5.2 minutes) and to defibrillation (7.4 versus 9.5 minutes). Conclusion: Collapse-to-intervention intervals, not emergency vehicle response intervals, should be used to characterize emergency medical services system performance in the treatment of sudden cardiac death.