The prognostic significance of coma-rating, duration of anoxia and cardiopulmonary resuscitation in out-of-hospital cardiac arrest

Early determination of outcome after successful prehospital cardiopulmonary resuscitation (CPR) is a common problem with great ethical, economic, social, and legal consequences. We prospectively investigated 112 adult patients who had been resuscitated after out-of-hospital cardiac arrest (CA). The aim of our study was to determine whether coma rating by the mobile intensive care unit (MICU) is a useful tool for outcome prediction. For neurological assessment the Innsbruck Coma Scale (ICS) was used initially and after return of spontaneous circulation (ROSC) or 20-30 min after the start of CPR, before any sedating drugs were given. The duration of anoxia and CPR were determined with the automatically recorded emergency call protocol of the dispatch centre and the protocol of the MICU. For estimation of cerebral outcome at the time of discharge from hospital we used the Glasgow-Pittsburgh Cerebral Performance Categories (CPC). Restoration of spontaneous circulation was achieved in 42 patients (37%), and 15 (13%) were discharged from hospital. The first coma rating performed immediately at the time of arrival on scene had no significant prognostic value for prediction of neurological outcome (P = 0.204) and survival (P = 0.103). The second coma rating (performed after ROSC or 20-30 min after the start of CPR), however, demonstrated a significant correlation with neurological outcome (P = 0.0000) and survival (P = 0.0000), a correlation which was comparable to both duration of anoxia and duration of CPR. In patients with out-of-hospital cardiac arrest prognostic information could be obtained with the ICS as early as 20-30 min after the start of cardiopulmonary resuscitation.