(Background)
For out-of-hospital cardiac arrest (OHCA) cases, we can expect a favorable cerebral function if the time between the first contact to patients and epinephrine administration is shorter. However, there were no previous studies reported the association with the time between 119-call to the first contact (response time), as well as the initial ECG rhythm.  
(Purpose) 
We examined how cerebral function is affected by administering epinephrine as following cardiac arrest protocol, regardless of the initial ECG rhythm and response time.  
(Method)
We analyzed 13,326 OHCA cases from Utstein-style data between 2011 and 2014 in Japan. We stratified into Early Response time (≦8 min) and Late Response time (>8 min,≦16 min). The multivariate logistic regression analysis was performed to see the relationship between epinephrine time and cerebral function in the each of response time group.
(Results)
In the Early Response time group, adjusted odds ratio of the Early Epinephrine time compared to the Late epinephrine time was as follows: VF/VT, 2.37 (1,74-3.25) and PEA/Asystole, 1.96 (1.06-3.56). In the Late Response time group, adjusted odds ratio was: VF/VT, 2.66 (1.76-4.05) and PEA/Asystole, 3.22 (1.59-6.63). 
(Conclusion)
For the epinephrine administration in OHCA cases, early administration of epinephrine will improve the ratio of favorable cerebral function regardless of the initial ECG rhythm and response time. Each local Medical Control Council is needed to consider the timing of early epinephrine administration.

Is Early Epinephrine Administration Still Effective when The Response Time Takes Longer?