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, scen e arrival, CPR, and initial defibrillation were determined from dispat ch records, recordings of arrest events, interviews with bystanders, a nd hospital records. Setting: Southwestern city (population, 400,000; area, 390 km2) with a two-tiered basic life support-advanced life supp ort emergency medical services system. Emergency medical technician-fi refighters without electrical defibrillation capability comprised the first response tier; firefighter-paramedics. were the second tier. Pat ients: One hundred eighteen cases of witnessed, out-of-hospital cardia c 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. S urvivors did not differ significantly from nonsurvivors in age, sex, o r basic life support or advanced life support response intervals. Surv ivors had significantly (P<.05) shorter intervals from collapse to CPR (1.7 versus 5.2 minutes) and to defibrillation (7.4 versus 9.5 minute s). Conclusion: Collapse-to-intervention intervals, not emergency vehi cle response intervals, should be used to characterize emergency medic al services system performance in the treatment of sudden cardiac deat h.