Bystander interventions for out-of-hospital cardiac arrests: substantiated critical components of the chain of survival

Early bystander cardiopulmonary resuscitation (CPR) and defibrillation are both vital components in the chain of survival following out-of-hospital cardiac arrest (OHCA) (1,2). Fortunately, bystander CPR rates in industrialized countries have recently increased from 30% to 50% (3-8). A Swedish analysis reported that CPR performed prior to emergency medical services (EMS) arrival was associated with a 30-day survival rate following OHCA more than twice as high as that associated with no CPR before EMS arrival (5). Further, bystander interventions (bystander CPR and defibrillation) were also associated with an increased likelihood of 1-month neurologically intact survival following OHCA according to an analysis of a Japanese nationwide registry (7). As neurological assessments fluctuate for at least 90 days following cardiac arrest, the American Heart Association (AHA) has recommended that longer-term end points (i.e., 90 days) coupled with neurocognitive and quality-of-life assessments should be considered (9). The AHA further suggests that researchers utilize either Cerebral Performance Categories or modified Rankin Scale for global outcomes of neurological assessment in patients following cardiac arrest (9). However, little is known regarding the impact of bystander intervention on long-term (i.e., >90 days following OHCA) neurologically intact survival (3,10).