Effects of dexmedetomidine on postoperative cognitive dysfunction in elderly patients undergoing general anesthesia

Objective To evaluate the effects of dexmedetomidine on postoperative cognitive dysfunction (POCD) in the elderly patients undergoing general anesthesia.Methods Ninety ASA physical status Ⅱ or Ⅲ patients,aged 65-76 yr,weighing 49-78 kg,scheduled for elective surgery under general anesthesia,were randomly assigned into 3 groups (n =30 each):control group (group C) and different doses of dexmedetomidine groups (D1 and D2 groups).Anesthesia was induced with midazolam,cisatracurium besilate,sufentanil and propofol.Dexmedetomidine 0.5 μg/kg was then intravenously infused over 15 min,followed by infusion at a rate of 0.50 μg· kg-1 · h-1 (group D1) or 0.75 μg· kg-1 · h-1 (group D2) until the end of surgery.Group C received the equal volume of normal saline.At 1 day before surgery and 1,3 and 7 days after surgery,venous blood samples were obtained for determination of serum concentrations of C-reactive protein (CRP) and neuron-specific enolase (NSE).The cognitive function was evaluated by Mini-Mental State Examination (MMSE) at the time points mentioned above.The development of POCD was recorded.Results Compared with group C,the MMSE scores were significantly increased and serum concentrations of CPR and NSE were decreased in groups D1 and D2,and no significant differences were found in the indexes mentioned above between D1 and D2 groups.The incidence of POCD was 30％,7％ and 7％ in C,D1 and D2 groups,respectively.The incidence of POCD was significantly higher in group C than in D1 and D2 groups,and there was no significant difference between D1 and D2 groups.Conclusion Dexmedetomidine is helpful in preventing the development of POCD in the elderly patients undergoing general anesthesia. Key words: Dexmedetomidine ;  Cognition disorders;  Aged