Background: The factors that influence survival of out-of-hospital cardiac arrest in Japan have not been fully investigated.
Methods and results: The official emergency service record was used to investigate 1,600 patients for whom cardiopulmonary resuscitation was attempted by the city's emergency personnel. Only 45 (2.8%) patients survived for 1 month. The survival rate was 9.8% in the patients under 20 years of age, with a marked decreasing trend to 0.8% in the patients aged 80 years or older. The rate peaked at 4.8% on Sunday and bottomed out at 0.5% on Thursday, forming a distinct sine curve. The survival rate was 9.9% when an ambulance arrived at the scene within 4 min, with a steep drop to 2.5% when 4-7 min elapsed. However, the rate was not significantly different by the interval to hospital. Although bystander resuscitation did not significantly affect the survival, paramedics on board significantly improved the rate (3.5% vs 1.6%). Multivariate analysis confirmed that age, day of the week, place, interval to ambulance's arrival, and personnel on board were independently associated with the probability of survival.
Conclusions: Quick arrival of a paramedic team would improve the survival after out-of-hospital cardiac arrest. General education of lifesaving techniques would be another key factor.