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.