Automatic external defibrillation and its effects on neurologic outcome in cardiac arrest patients in an urban, two-tiered EMS system.

OBJECTIVE: To describe the use of the Automatic External Defibrillation (AED) device in an urban, two-tiered Emergency Medical Service (EMS) response setting with regard to its potential effects on cardiac arrest patient survival and neurologic outcome. METHODS: A retrospective and descriptive design was utilized to study all cardiac arrest patients that had resuscitations attempted in the prehospital environment over a 30-month period. The study took place in a two-tiered EMS system serving an urban population of 368,383 persons. The first tier of EMS response is provided by the City Fire Department, which is equipped with a standard AED device. All first-tier personnel are trained to the level of Emergency Medical Technician-Basic. The second tier of EMS response is provided by personnel from one of two ambulance services. All second-tier personnel are trained to the level of Emergency Medical Technician-Paramedic. RESULTS: 271 cardiac arrest patients were identified for inclusion. One-hundred nine of these patients (40.2%) had an initial rhythm of either ventricular fibrillation or pulseless ventricular tachycardia and were shocked using the AED upon the arrival of first-tier personnel. Forty-two patients (38.5%) in this group had a return of spontaneous circulation in the field and 22 (20.2%) survived to hospital discharge. Of the survivors, 17 (77.3%) had moderate to good neurologic function at discharge based on the Glasgow-Pittsburgh Cerebral Performance Categories. Faster response times by the first-tier personnel appeared to correlate with better neurologic outcomes. CONCLUSION: First responder-based AED usage on patients in ventricular fibrillation or pulseless ventricular tachycardia can be applied successfully in an urban setting utilizing a two-tiered EMS response. In this study, a 20.2% survival to hospital discharge rate was obtained. Seventy-seven percent of these survivors had a moderate to good neurologic outcome based on the Glasgow-Pittsburgh Cerebral Performance Categories.