Abstract 2224: Survival after EMS witnessed cardiac arrest. Observations from the Resuscitation Outcomes Consortium (ROC) Epistry â “ Cardiac Arrest
Introduction: Out-of-hospital cardiac arrest (OHCA) is common and lethal. It has been suggested that patients with OHCA witnessed by emergency medical services (EMS) providers is a predictor of survival since prodromal symptoms reached a threshold sufficient to call for help.
Hypothesis: Survival is uniformly distributed between EMS-witnessed, bystander-witnessed, and unwitnessed OHCA.
Methods: Design-Population-based cohort study. Setting-10 US and Canadian sites participating in the ROC, a prehospital clinical trials network. Inclusion-Individuals with non-traumatic OHCA from 12/01/05 to 11/30/06 treated by EMS providers with defibrillation or chest compressions. These were grouped into EMS-witnessed (EMSW), bystander witnessed (BW), and unwitnessed (UW). BW and UW were further stratified for bystander CPR. Multiple logistic regression evaluated the odds ratio (OR) for survival to discharge after adjusting for age, sex, location, and ROC site.
Results: Of 9886 OHCA, 921 (9.4%) were EMSW, 4053 (41.0%) BW, and 4912 (49.6%) UW. EMSW had more female subjects than BW and UW (43.6%, 32.8%, 36.13%, p<0.001). The most common initial rhythm in the EMSW group was PEA which was higher than in the BW and UW groups (41.7%, 21.0%, 14.2%, p<0.001). The adjusted OR (95% CI) for survival is presented in the table⇓.
Conclusions: Survival was higher after EMS-witnessed OHCA. Limitations include lack of knowledge of the cause of the initial call for EMS, as well as differences in the timing of initial rhythm assessment between groups. The immediate application of advanced prehospital care after the onset of OHCA may improve survival.