Effects of dexmedetomidine on postoperative cognitive function in aged patients undergoing carotid endarterectomy

Objective To evaluate the effects of dexmedetomidine on postoperative cognitive function in the aged patients undergoing carotid endarterectomy.Methods Forty patients,aged 65-80 yr,of ASA physical status Ⅱ or Ⅲ,scheduled for elective carotid endarterectomy,were randomly divided into 2 groups (n =20 each):control group (group C) and dexmedetomidine group (group DEX).Anesthesia was induced with midazolam,etomidate,fentanyl and rocuronium.The patients were tracheally intubated.In group DEX,a loading dose of dexmedetomidine 0.03 μg· kg-1 ·min-1 was infused intravenously for 10 min starting from the time point before induction,and dexmedetomidine 0.30μg· kg-1 ·min-1 was infused until 30 min before the end of operation starting from the end of intubation.The equal volume of normal saline was given instead of dexmedetomidine in group C.At 1 day before operation (To) and 6 and 24 h after operation (T1.2),venous blood samples were collected for determination of serum brain-derived neurotrophic factor (BDNF) concentrations.The cognitive function of the patients was assessed using Mini-Mental State Examination (MMSE) at To,T2,and 48 h,72 h,7days and 1 month after operation (T3-6).Results Compared with the baseline value at T0,the serum BDNFconcentrations were significantly increased at T1 in the two groups,MMSE scores were decreased at T2,3 in groupC,and MMSE scores were decreased,and the serum BDNF concentrations were increased at T2 in group DEX.Compared with group C,the MMSE scores were significantly increased at T3.4,the serum BDNF concentrations were increased at T2,and no significant change was found in MMSE scores at T5.6 in group DEX.Conclusion Dexmedetomidine is helpful in improving postoperative cognitive function and in promoting the recovery of postoperative cognitive function,and the mechanism may be related to enhanced production of endogenous BDNF in the aged patients undergoing carotid endarterectomy. Key words: Dexmedetomidine ;  Endarterectomy, carotid ;  Cognition disorders ;  Aged