Out-of-hospital cardiac arrests of non-cardiac origin. Epidemiology and outcome.

AIMS: The aim of the study was to determine the epidemiology of out-of-hospital cardiac arrests of non-cardiac origin and survival following resuscitation, using the Utstein method of data collection. METHODS AND
RESULTS: The study was of prospective cohort design and was conducted in a middle-sized urban city (population 525000) served by a single emergency medical services system. Consecutive out-of-hospital cardiac arrests of non-cardiac origin occurring between 1 January 1994 and 31 December 1995 were included. Survival from cardiac arrest to hospital discharge, and factors associated with survival were considered as main outcome measures. Of the 809 patients, 276 (34.1%) had a cardiac arrest of non-cardiac origin. The mean (SD) age of the patients was 49.8 (20.9) years. Resuscitation was attempted in 204 cases, 82 of whom (40.2%) were hospitalized alive and 23 (11.3%) were discharged. Thirteen (56.5%) of the survivors were discharged neurologically intact or with mild disability (overall performance category I or II). The survivors, during the study period, who suffered an out-of-hospital cardiac arrest of non-cardiac origin comprised 19.2% of all out-of-hospital cardiac arrest survivors. Trauma (62), non-traumatic bleeding (36), intoxication (31), near drowning (22) and pulmonary embolism (18) were the most common aetiologies, comprising 61.2% of cases. The non-cardiac aetiology was suspected pre-hospital in 176 (63.8%) cases; in the remaining cases, the aetiology was revealed only after in-hospital investigations or autopsy. In a logistic regression model, time interval to first responding unit, collapse outside the home, and aetiologies of near-drowning, airway obstruction, intoxication and convulsions were associated with survival.
CONCLUSIONS: These results indicate that sudden out-of-hospital cardiac arrest more often has a non-cardiac cause than previously believed. Although survival is not as likely as from cardiac arrest of cardiac origin, since non-cardiac-cause survivors comprise one fifth of all out-of-hospital cardiac arrest survivors, resuscitation efforts are worthwhile.