Objective:Epinephrine is the primary drug administered during cardiopulmonary resuscitation (CPR) to reverse cardiac arrest.The evidence for the use of adrenaline in out-of-hospital cardiac arrest (OHCA) and in-hospital resuscitation is inconclusive.We conducted a systematic review on the clinical efficacy of adrenaline in adult OHCA patients to evaluate whether epinephrine provides any overall benefit for patients.Data Sources:The EMBASE and PubMed databases were searched with the key words epinephrine, cardiac arrest, and variations of these terms.Study Selection:Data from clinical randomized trials,meta-analyses,guidelines,and recent reviews were selected for review.Results:Sudden cardiac arrest causes 544,000 deaths in China each year,with survival occurring in ＜1％ of cases (compared with 12％ in the United States).The American Heart Association recommends the use of epinephrine in patients with cardiac arrest,as part of advanced cardiac life support.There is a clear evidence of an association between epinephrine and increased ret of spontaneous circulation (ROSC).However,there are conflicting results regarding long-term survival and functional recovery,particularly neurological outcome,after CPR.There is currently insufficient evidence to support or reject epinephrine administration during resuscitation.We believe that epinephrine may have a role in resuscitation,as administration of epinephrine during CPR increases the probability of restoring cardiac activity with pulses,which is an essential intermediate step toward long-term survival.Conclusions:The administration of adrenaline was associated with improved short-term survival (ROSC).However,it appears that the use of adrenaline is associated with no benefit on survival to hospital discharge or survival with favorable neurological outcome after OHCA,and it may have a harmful effect.Larger placebo-controlled,double-blind,randomized control trials are required to definitively establish the effect of epinephrine.