b'EtiologyIn alignment with the latest ILCOR guidelines, CARES requires that all EMS-treated, non-traumatic cardiac arrests be entered into the registry. The etiology of arrest is determined by field providers and documented in the patient care record. Following the Utstein guidelines, an arrest is presumed to be of cardiac etiology unless it is clearly documented otherwise.In 2023, 82.4% of adult (18 years of age) OHCAs were presumed to be of a cardiac cause. Other causes of adult OHCA included: respiratory/asphyxia (8.8%), drug overdose (7.0%), exsanguination/hemorrhage (0.7%), drowning/submersion (0.5%), and other medical (0.6%) (Figure 3).The etiology of arrest for pediatric patients (18 years of age) differed substantially from that of adults. In 2023, 42.6% of pediatric arrests were presumed to be of a cardiac etiology. Other causes of pediatric OHCA included: respiratory/asphyxia (38.8%), drowning/submersion (7.9%), drug overdose (6.1%), SIDS/SUID (3.0%), and other medical (1.6%) (Figure 4).0.7% 0.5% 0.6% 7.9% 1.6%7.0% 3.0%8.8% 6.1%42.6%82.4% 38.8%Presumed Cardiac Etiology Respiratory/Asphyxia Presumed Cardiac Etiology Respiratory/AsphyxiaDrug Overdose Exsanguination/Hemorrhage Drug Overdose SIDSDrowning/Submersion Other Drowning/Submersion OtherFigure 3. Etiology of arrest for adults. Figure 4. Etiology of arrest for pediatric patients.Figure 5 further illustrates the relationship between arrest etiology and patient age. Presumed cardiac cause was the most predominant etiology across all age groups, with the proportion of arrests attributable to this cause increasing with patient age. However, pediatric patients were much more likely than adults to experience an arrest due to respiratory cause. Drug overdose accounted for 35.6% of arrests in the 19-34 age group and 20.1% of arrests in the 35-49 age group, highlighting the continued impact of the opioid epidemic in the United States.100%90%84%80%68%60%49%43% 39%40% 36%20%20% 12% 11%6% 9% 9% 6% 8%4% 3% 1% 1% 1%0% 18 19-34 35-49 50-6465Age Group (years)Presumed Cardiac Respiratory/Asphyxia Drug Overdose OtherFigure 5. Etiology of arrest by age group.30 31'