A Utstein-style analysis of prognostic factors related to survival in out-of-hospital cardiac arrests in Akita-City, Japan

To analyze the epidemiology of out-of-hospital cardiac arrests and to eluci date modifiable factors affecting survival, we conducted a prospective coho rt study in a middle-sized urban city served by a single emergency medical service (EMS) system in which emergency medical technicians use an automate d external defibrillator. Data were collected from out-of-hospital cardiac arrests occurring between 1 January, 1994 and 31 December, 1998 by applying the Utstein style. The main outcome measure was survival at 1 year after h ospital discharge. The overall incidence of out-of-hospital cardiac arrest was 71.7/100000 inhabitants/year. Resuscitations were attempted in 762 of. 1118 patients with confirmed cardiac arrest. Of the 762 patients, 37 (4.86% ) survived. The cause of cardiac arrest was presumed to be cardiac in 340 ( 44.6%). Of the 340 cardiac arrests, 180 (52.9%) were witnessed by bystander s. Ventricular fibrillation (VF) was recorded as an initial rhythm in 56 (3 1.1%) of the 180 patients, and cardiopulmonary resuscitation (CPR) was perf ormed by bystanders in 89 (49.4%). The survival rate was 39.2% (22/56) when cardiac arrest was bystander-witnessed and of cardiac origin with VF as an initial rhythm. VF as an initial rhythm, age of the patients and intervals of call-to-first CPR attempt and collapse-to-arrival at patient's side wer e major factors relating to survival in the witnessed cardiac arrests of ca rdiac origin. The age, and gender of the patients, place of collapse and in tervals of collapse-to-first CPR and collapse-to-arrival at patient's side were representative factors affecting the incidence of VF as an initial rhy thm. The survival rate in Akita-City from bystander-witnessed cardiac arres ts of cardiac origin with VF as an initial rhythm was comparable to those i n other regions with advanced EMS systems. However, the incidence of VF as an initial rhythm is extremely low. Reduction of intervals of call (collaps e)-to-first CPR attempt and collapse-to-arrival at patient's side or author ization of use of automated external defibrillator in basic life support ma y increase the incidence of VF as an initial rhythm and improve the surviva l from witnessed cardiac arrests with cardiac origin.