Abstract 43: Patient Characteristics and Outcomes of Witnessed Out-of-Hospital Cardiac Arrest in Osaka: A 7-Year Emergency Medical Services Perspective in a Large Population
Objectives: To evaluate the temporal trend of baseline characteristics, resuscitation care characteristics, and outcomes of out-of-hospital cardiac arrests (OHCA) from a large population-based cohort study.
Methods: We enrolled all OHCAs of presumed cardiac etiology in adults (>17 years old) that were witnessed by bystanders and were treated by emergency medical service (EMS) in Osaka Prefecture (population, 8.8 million), Japan from 1999 through 2005. Data were prospectively collected by EMS personnel and physicians in charge using an Utstein-style database. Time course was divided into 7 successive one-year periods. We evaluated changes in demographic and cardiopulmonary resuscitation (CPR)-related factors, and outcomes. Multivariate logistic regression analysis was performed to evaluate the relationship between prognostic factors and outcomes.
Results: Mean age gradually increased over time. The proportion of cases with bystander CPR and with ventricular fibrillation (VF) increased. The time interval from emergency call to the first defibrillation by EMS personnel shortened from 14 to 8 min, while the time to the initiation of CPR by EMS remained 6 –7 min. Neurologically favorable outcome 1-month after arrest improved from 1.5% to 4.7% in the entire cohort (Table⇓) and from 5.5% to 16.9% in witnessed VF cases during the observation period. Excluding very-long-duration cardiac arrests (>15 minutes), bystander-initiated cardiac-only resuscitation yielded a higher rate of favorable neurological outcome than no bystander CPR (3.6% versus 2.8%; OR, 1.51; 95% CI, 1.00 –2.26), and conventional CPR showed similar effectiveness (3.6%; OR, 1.39; 95% CI, 0.96 –2.02).
Conclusion: This study showed the continuous improvement of the chain of survival and outcomes of patients with witnessed OHCA in a large population. Further efforts to increase bystander-initiated cardiac-only resuscitation would improve the outcomes more.