An analysis of time factors in out-of-hospital cardiac arrest in Osaka Prefecture

Objective: To ascertain important factors in the improvement of out-of-hospital cardiac arrest survival rates through analysis of data for Osaka Prefecture with the focus on time factors. Design: Prospective cohort study according to the Utstein style. Setting: Osaka Prefecture (population 8 830 000) served by a single emergency medical services system. Patients: Consecutive prehospital cardiac arrests occurring between May 1998 and April 1999. Main outcome measures: One-year survival from cardiac arrest, and time factors. Result: Of the 5047 cases of confirmed cardiac arrests, resuscitation was attempted in 4871 subjects. Of the 982 cases of cardiac origin and witnessed by bystanders, 31 (3.2%) were still alive, and of the 576 cases of non-cardiac origin and witnessed by bystanders, ten (1.7%) were still alive at the 1 year follow-up. The median time from receipt of the emergency call until ambulance arrival was 5 min and that from receipt of the call until the start of cardiopulmonary resuscitation (CPR) was 7 min. For the 214 patients for whom defibrillation was attempted, the median time from receipt of the call until the first shock was 15 min. The median time from receipt of the call until departure of the ambulance from the scene was 16 min and that until arrival of the ambulance at a hospital was 22 min. Conclusions: This study using the standardized format according to the Utstein style clearly elucidates the specific delay of the start of defibrillation by paramedics and also indicates the inappropriate rule for this procedure in Japan.