Effects of dexmedetomidine on postoperative cognitive function and monocytes Toll-like receptor 2 and Tolllike receptor 4 expression in elderly patients

Abstract

Objective To investigate the effects of dexmedetomidine on postoperative cognitive function and monocytes Toll-like receptor 2 (TLR2)and TLR 4 expression in elderly patients.Methods Forty-five ASA Ⅰ or Ⅱ elderly patients aged ≥65 yr weighing 53-72 kg were randomly divided into 3 groups: control group (group Ⅰ ) and different doses of dexmedetomidine groups(groups Ⅱ and Ⅲ ).Dexmedetomidine 1.0 μg/kg was injected iv over 15 min after anesthesia induction,and then was infused at a rate of 0.5 μg·kg-1 ·h-1 (group Ⅱ ) or 1.0 μg· kg-1 ·h-1 (group Ⅲ ) untile the end of operation.Group Ⅰ received equal volume of normal saline.Blood samples were taken before anesthesia induction,at 1.5 h after the beginning of operation,at the end of operation and at 24 h after operation(T,-T5 ) for determination of monocytes TLR2 and TLR4 expression by flow cytometrybased method.Postoperative cognitive function was evaluated at 1 d before and 7 d after operation with Mini-mental state examination and Wechsler memory scale and Wechsler adult intelligence scale,and the postoperative cognitive dysfunction was recorded.Results The incidence of postoperative cognitive dysfunction and monocytes TLR2 and TLR4 expression were significantly lower in groups Ⅱ and Ⅲ than in group Ⅰ,and in group Ⅲ than in group Ⅱ (P ＜ 0.05).Conclusion Dexmedetomidine can prevent postoperative cognitive dysfunction in elderly patients,and the mechanism may be related to down-regulation of monocytes TLR2 and TLR4 expression. Key words: Dexmedetomidine; Cognition disorders; Toll-like receptor 2; Toll-like receptor 4; Aged