PARAMEDIC 2 trial
By Prof Tom Quinn
The Prehospital Assessment of the Role of Adrenaline; Measuring the Effectiveness of Drug administration In Cardiac arrest (PARAMEDIC 2) trial was a multi-centre double-blind placebo-controlled trial conducted in 5 UK ambulance services (population 24 million) from 2014-2017. Patients who met trial inclusion criteria were individually randomised to adrenaline (n=4015) or placebo (n=3999). The primary outcome was survival to 30 days, secondary outcomes included rate of survival to discharge with favourable neurological outcome indicated by modified Rankin scale of 3 or less. 130 patients (3.2%) in the adrenaline group and 94 (2.4%) patients in the placebo group were alive at 30 days. No significant difference in survival with favourable neurological outcome was observed, but more survivors in the adrenaline group had severe neurological impairment.
Adrenaline (epinephrine) has been used to treat cardiac arrest for over half a century, but has not been formally tested in a completed randomised trial to evaluate whether it is helpful or harmful. Concerns have been raised in recent years, based largely on registry data, that adrenaline may increase return of spontaneous circulation (ROSC) but not survival with favourable neurocognitive outcomes. This is the largest randomised trial to date addressing the effectiveness of adrenaline in out of hospital cardiac arrest. The main trial findings were increased survival at 30 days (number needed to treat 112) but did not improve survival with a favourable neurological outcome in the adrenaline group, suggest that while adrenaline may be good for the heart, it does not help the brain.