Effects of dexmedetomidine on changes of cognitive function in patients undergoing cardiac valve replacement with cardiopulmonary bypass

Objective To explore the effects of dexmedetomidine(DEX) on the changes of patient' s cognitive function after undergoing cardiac valve replacement with cardiopulmonary bypass(CPB).Methods Sixty patients to selectively receive cardiac valve replacement with CPB were randomly divided into two groups:DEX group(n =30) and normal saline group(NS group,n =30).DEX (0.5 μ.g/kg bolus and infusion at a rate of 0.5 μg · kg-1 · h-1) was administered to the patients of DEX group,and the patients of NS group were given with equivalent normal saline at the same time.Aortic clamped time,CPB time,duration of anesthesia and PaO2 at 10 min before CPB were recorded.Heart rate(HR),mean arterial pressure(MAP),jugular venous oxygen saturation(SJvO2) and jugular venous oxygen partial pressure(PJvO2) of anesthesia induction(T0),10 min after induction(T1),CPB re-warmed to 36℃ (T2),and 1 h(T3),6 h(T4),24 h (T5),48 h (T6),72 h (T7) after CPB were performed.MMSE were performed 3 days after surgery,the incidence of POCD was calculated.Results There was no statistical significance in aortic clamped time,duration of CPB,anesthesia time and PaO2 at 10 min before CPB (P ＞ 0.05) between both of groups.Compared to TO,SJvO2 and PJvO2 of NS group from T1 to T2,T4 to T7 and DEX group at T1,T4 to T7 were decreased(P＜0.05,P＜0.01).Compared to NS group,SJvO2 and PJvO2 of DEX group from T2 to T3 were increased(P ＜ 0.01).MMSE evaluation and the incidence of POCD of DEX group were better than those of NS group 3 days af ter surgery(P ＜0.05,P ＜ 0.01).Conclusion Cardiac valve replacement with CPB can lead to cognitive impairment in pa tients,dexmedetomidine can ameliorate cognitive function by decreasing oxygen consumption in brain tissue. Key words: Dexmedetomidine ;  Cardiopulmonary bypass ;  Cognitive dysfunction ;  Postoperative complications