Abstract: Objective:To observe the efficacy and safety of dexmedetomidine(Dex) in cardiopulmonary bypass(CPB) surgery.Methods:One hundred and twenty heart disease patients scheduled by CPB surgery were randomly divided into the control group(group C) and observation group(group D)(60 cases each group).The control group was generally anesthetized induction with 0.05 mg/kg of midazolam,0.2 to 0.3 μg/kg of sufentanil,1 to 2 mg/kg of propofol and 0.2 mg/kg of cisatracurium,and sufentanyl was continuously infused at the rate of 0.1 μg·kg^-1·h^-1 until the end of CPB after endotracheal intubation.The 1 μg/kg of Dex in group D was infused for 10 min before anesthesia,The group D was intubated under general anesthesia induction as the group C after 5 min of infusion of Dex,and then continuously infused with Dex at the rate of 0.5 μg·kg^-1·h^-1 until the end of CPB.The heart rate and average arterial pressure in two groups were recorded at each time-point.The levels of venous serum cortisol(COR) and aldosterone(ALD) in two groups were compared.The Dex-related adverse reactions(hypotension,hypertension,bradycardia and cardiac arrest) and incidence rates of adverse reactions(lung infection,cognitive function,stroke,paralysis and death) within 2 weeks after operation were recorded.Results:Compared with group C,the heart rate and average arterial pressure at each time-point in group D were lower(P <0.05 to P <0.01).The levels of COR and ALD in group D were lower than those in group C(P<0.01).The difference of the incidence rate of adverse reaction within 2 weeks after operation between two groups was not statistically significant(P>0.05).Conclusions:The application of Dex in CPB surgery can alleviate the hemodynamic fluctuation during operation,decrease the serum COR and ALD levels,reduce stress reactions and improve the perioperative quality of rehabilitation of patients to some extent,which is worthy of promotion.