Purpose:
International resuscitation guidelines recommend prehospital adrenaline for out-of-hospital cardiac arrest (OHCA), but evidence for a beneficial effect on survival remains equivocal. Studies also show significant variability in adrenaline administration between and within Emergency Medical Services (EMS) systems worldwide, but there is a paucity of published UK data. This study therefore describes the epidemiology and outcomes for OHCA patients receiving prehospital adrenaline by EMS in the UK.
Materials and Methods:
Retrospective observational study. Data on adult OHCA patients receiving adrenaline from eight English and the Welsh ambulance service regions analysed from two sources: secondary analysis of 2010-2013 data from the PARAMEDIC mechanical chest compression device RCT, and 2013-2015 data from the OHCA Outcomes (OHCAO) project, a UK registry. Chi-square tests were used to test differences in proportions of adrenaline administration between EMS regions. Descriptive statistics were used to report patient demographic and clinical characteristics, bystander response, EMS response time and outcomes.
Results:
EMS treated 47,737 OHCA patients with 36,998 (77.5%) administered adrenaline. Administration varied between EMS regions ranging from 62.2-86.3% (overall difference p<0.001) for all patients, 59.9-85.3% (overall difference p<0.001) for shockable and 66.0-91.0% (overall difference p<0.001) for non-shockable rhythm patients. Mean age of patients administered adrenaline was 71.0 (SD = 16.4) years and 63.0% were male. The bystander CPR rate (non-EMS witnessed cases) was 54.2%. Cardiac was the main cause of OHCA (88.6%), whilst the initial rhythm was non-shockable in 78.1% of patients. Mean EMS response time was 7.8 (SD = 7.1) minutes. The ROSC at hospital transfer rate was 22.8% and survival to discharge was 2.9% for patients administered adrenaline.
Conclusions:
A high proportion of OHCA patients received prehospital adrenaline from EMS between 2010-2015 in England and Wales, with significant variability in administration found between EMS regions. Patients administered adrenaline had an overall low survival to discharge rate.

7 - Prehospital adrenaline administration for out-of-hospital cardiac arrest: The picture in England and Wales.