Association of Scene Time Interval and Field Arrival to Epinephrine Administration Time with Outcomes in Cardiac Arrest

<b>Background/Objectives:</b> The association of scene time interval (STI) and field arrival to epinephrine administration time (FET) with outcomes in out-of-hospital cardiac arrest (OHCA) is unknown. The goal of this investigation is to assess the association of STI and FET with outcomes in OHCA. <b>Methods</b>: All adult OHCA cases with prehospital epinephrine administration in South Korea and Singapore were included. STI was divided into short and long stay based on the median value of each country. FET was categorized into early (<10 min) and late groups. We performed multivariable logistic regression for survival to discharge and good neurological recovery. Cases were grouped into short stay early epinephrine (SS-EE), short stay late epinephrine (SS-LE), long stay early epinephrine (LS-EE), and long stay late epinephrine (LS-LE) (reference). Interaction analysis with STI and FET for outcomes was conducted. <b>Results:</b> A total of 18,867 cases from South Korea and 4184 cases from Singapore were included. Adjusted odds ratio (AOR) for survival to discharge was 2.14 (95% CI: 1.18-2.25) in SS-EE, 1.15 (0.94-1.40) in SS-LE, and 1.82 (1.45-2.28) in LS-EE compared to LS-LE in South Korea with similar results for Singapore. SS-EE and LS-EE were also associated with good neurologic recovery. Interaction analysis showed that early epinephrine injection in short stay and long stay was associated with better outcomes. But short STI was not associated with better outcomes in early and late epinephrine groups. <b>Conclusions:</b> Early epinephrine administration was associated with higher survival to discharge irrespective of the scene time interval.