Objectives: To study the factors associated with short- and long-term survival after asystolic out-of-hospital cardiac arrest, with a reference to medical futility.
Methods: This is a retrospective observational study conducted in Helsinki, Finland during 1 January 1997 to 31 December 2005. All out-of-hospital cardiac arrests were prospectively registered in the cardiac arrest database. Of 3291 arrests, 1455 had asystole as the first registered rhythm. These patients represent the study population.
Results: A short time interval to the initiation of advanced life support (ALS) was associated with a long-term benefit, but a short first responding unit (FRU) response time had only a short-term benefit. Conversion of asystole into a shockable rhythm provided only a short-term benefit. The prognosis was poor if the FRU response time was over 10 min or the ALS response time was over 11 min in bystander-witnessed arrests, and if the duration of resuscitation was over 8 min in emergency medical services (EMS)-witnessed arrests. Bystander-CPR was associated with increased 30-day mortality. The 30-day survival rate after an unwitnessed arrest (n=548) was 0.5%. All survivors in this group were either hypothermic or were victims of near-drowning.
Conclusions: Resuscitation should be withheld in cases of unwitnessed asystole, excluding cases of hypothermia and near-drowning. The prognosis is poor if the FRU response time is over 10 min or the ALS response time is over 10–15 min in bystander-witnessed arrests. The decision of whether or not to attempt resuscitation should not be influenced by the presence of bystander-CPR. Early initiation of ALS should be prioritised in the treatment of out-of-hospital asystole.