Can we define patients with no and those with some chance of survival when found in asystole out of hospital?

We describe the epidemiology, prognosis, and circumstances at resuscitation among a consecutive population of patients with out-of-hospital cardiac arrest (OHCA) with asystole as the arrhythmia first recorded by the Emergency Medical Service (EMS), and identify factors associated with survival. We included all patients in the municipality of Göteborg, regardless of age and etiology, who experienced an OHCA between 1981 and 1997. There were a total of 4,662 cardiac arrests attended by the EMS during the study period. Of these, 1,635 (35%) were judged as having asystole as the first-recorded arrhythmia: 156 of these patients (10%) were admitted alive to hospital, and 32 (2%) were discharged alive. Survivors were younger (median age 58 vs 68 years) and had a witnessed cardiac arrest more often than nonsurvivors (78% vs 50%). Survivors also had shorter intervals from collapse to arrival of ambulance (3.5 vs 6 minutes) and the mobile coronary care unit (MCCU) (5 vs 10 min), and they received atropine less often on scene. There were also a greater proportion of survivors with noncardiac etiologies of cardiac arrest (48% vs 27%). Survivors to discharge also displayed higher degrees of consciousness on arrival to the emergency department in comparison to nonsurvivors. Multivariate analysis among all patients with asystole indicated age (p = 0.01) and witnessed arrest (p = 0.03) as independent predictors of an increased chance of survival. Multivariate analysis among witnessed arrests indicated short time to arrival of the MCCU (p < 0.001) and no treatment with atropine (p = 0.05) as independent predictors of survival. Fifty-five percent of patients discharged alive had none or small neurologic deficits (cerebral performance categories 1 or 2). No patients > 70 years old with unwitnessed arrests (n = 211) survived to discharge.