b'EARLY DEFIBRILLATION With more than 15% of OHCAs occurring in public locations, the role of public access AEDs and community training have a large role to play in early defibrillation. However, the application of AEDs applied by bystanders remains relatively low, occurring after only 12.6% of public arrests.In 2024, 29.2% (n=40,031) of CARES patients were defibrillated in the field. Among these patients, 5.8% were initially defibrillated by a bystander, while 23.6% and 70.6% were first defibrillated by a first responder or EMS personnel, respectively.Reducing delays to defibrillation leads to improved outcomes for patients in a shockable rhythm. Unadjusted outcomes for this subset of patients vary based on who performed the first defibrillation (Figure 15). The proportion of OHCA patients surviving to hospital discharge when first defibrillated by a bystander with an AED was 47%, compared to 28% of patients first shocked by a first responder and 27% by responding EMS personnel.Survival OutcomesPATIENT OUTCOMESBased on local EMS agency protocols, 43.0% of patients were pronounced on scene after resuscitative efforts were terminated in the pre-hospital setting (Figure 16). The success of resuscitation efforts in the field is often measured by a patients return of spontaneous circulation (ROSC). In 2024, sustained ROSC (defined as 20 consecutive minutes of ROSC, or its presence at transfer of care to a receiving hospital) was achieved by 25.4% of CARES patients.The rate of survival to hospital admission was 25.7% (ED outcome missing for 287 cases; 0.2%), and the rate of survival to hospital discharge was 10.5% (hospital outcome missing for 334 cases; 0.2%). Among patients discharged alive, the majority had a neurologically favorable outcome, indicated by a Cerebral Performance Category (CPC) score of 1 or 2 (Table 3).Figure 16. Unadjusted pre-hospital and in-hospital OHCA patient outcomes.41'