Introduction: The epinephrine administration in the pre-hospital setting has been evaluated for its time relation compared with those who were not administered. However, the relation between the effect of bystander cardiopulmonary resuscitation (BCPR) and epinephrine administration time is not discussed.
Purpose:The purpose of this study was to demonstrate whether the effect of epinephrine administration is enhanced by the presence of bystander CPR.
Material: This nationwide population-based observational study using Utstein data from 2011 to 2014 was conducted in Japan. We extracted 19,917 patients with bystander-witnessed out-of-hospital cardiac arrest (OHCA) presumed cardiac origin who administered epinephrine. Database were divided into two groups depending on if patients received BCPR or not.The corelation between each group of epinephrine administration time and prognosis at 1 month survival was evaluated. The study outcome: CPC(Cerebral Performance Category) 1-2. Statistical analysis : The adjusted odds ratio(AOR), crude odds ratio (COR) and 95% confidence interval (CI) were estimated.
Results:There was statistically no difference between BCPR and non-BCPR effect on epinephrine administration(AOR; 1.16, 95%CI; 0.93 to 1.44). However, in the  late-epinephrine administration, the effect of BCPR to CPC 1-2 was higher(AOR; 1.85, 95%CI; 1.05 to 3.26).
Conclusion:It was found that the combination effect of bystander CPR and epinephrine administration improved the favorable neurologic outcome. However, the implementation rate of BCPR is still not satisfied in Japan. Increasing the number of layperson BLS, the effect of EMS advanced life support can be enhanced.

5 - A factor improving the effect of pre-hospital epinephrine administration.