Management of EMS on-scene time during advanced life support in out-of-hospital cardiac arrest: a retrospective observational trial

Objective: Most western emergency medical services provide advanced life support in out-of-hospital cardiac arrest aiming for a return of spontaneous circulation at the scene. Little attention is given to prehospital time management in the case of out-of-hospital cardiac arrest with regard to early coronary angiography or to the start of extracorporeal cardiopulmonary resuscitation treatment within 60 minutes after out-of-hospital cardiac arrest onset. We investigated the emergency medical services on-scene time, defined as emergency medical services arrival at the scene until departure to the hospital, and its association with 30-day survival with favourable neurological outcome after out-of-hospital cardiac arrest.

Methods: All patients of over 18 years of age with non-traumatic, non-emergency medical services witnessed out-of-hospital cardiac arrest between July 2013 and August 2015 from the Vienna Cardiac Arrest Registry were included in this retrospective observational study.

Results: Out of 2149 out-of-hospital cardiac arrest patients, a total of 1687 (79%) patients were eligible for analyses. These patients were stratified into groups according to the on-scene time (<35 minutes, 35-45 minutes, 45-60 minutes, >60 minutes). Within short on-scene time groups, out-of-hospital cardiac arrest occurred more often in public and bystander cardiopulmonary resuscitation was more common (both P<0.001). Patients who did not achieve return of spontaneous circulation at the scene showed higher rates of 30-day survival with favourable neurological outcome with an on-scene time of less than 35 minutes (adjusted odds ratio 5.00, 95% confidence interval 1.39-17.96).

Conclusion: An emergency medical services on-scene time of less than 35 minutes was associated with higher rates of survival and favourable outcomes. It seems to be reasonable to develop time optimised advance life support protocols to minimise the on-scene time in view of further treatments such as early coronary angiography as part of post-resuscitation care or extracorporeal cardiopulmonary resuscitation in refractory out-of-hospital cardiac arrest.