CARES Annual Report 2017 | 21 Chain of Survival The chain of survival refers to a series of actions intended to maximize the chances of survival following cardiac arrest. The five links in the chain of survival are early access to care, early CPR, early defibrillation, rapid delivery of EMS care, and early post-resuscitative care. For every minute of cardiac arrest without CPR or defibrillation, a patient’s chance of survival falls by 7-10% 5 . This means that the community and bystander response are integral to survival from OHCA. Early Access to Care The first step in the chain of survival is recognition of cardiac arrest and activation of the emergency response system by calling 911. The next crucial time period is the interval between call receipt at the dispatch center to arrival on scene, or “response time”. The distribution of First Responder and EMS response times are presented in Figure 10. Response and treatment times are supplemental elements in CARES; however, participants are encouraged to measure response times in order to identify local opportunities for improvement. Records with missing response times (21.3%) as well as those that were witnessed by a 911 Responder (12.3%), have been excluded from response time analyses. In 2017, median response time by First Responders was 6.2 minutes (IQR: 4.8 - 8.6 minutes) and median response time by EMS was 7.3 minutes (IQR: 5.4 - 10.1 minutes). First Responders arrived on scene in ≤ 5 minutes for 31.2% of arrests, while EMS arrived on scene in ≤ 9 minutes for 67.6% of arrests. Figure 10. Distribution of First Responder and EMS response times (time interval from 911 call to arrival on scene).