Effects of Dexmedetomidine on Postoperative Cognitive Function in Elderly Patient

Objective To investigate the effects of dexmedetomidine on postoperative cognitive function and possible mechanism in elderly patients.Methods Forty-six ASA I or II elderly patients were randomly divided into 2 groups:control group(group I)and dexmedetomidine group(group II).Dexmedetomidine was injected i.v.over 10-15 min before ane-sthesia induction,and then was infused at a lower rate(group II) until the end of operation.Group I received equal volume of normal saline.The plasma cortisol concentrations were detected at 3 time points:before anesthesia,at 1h after the beginning of operation and at the end of operation.Postoperative cognitive function was evaluated at 1 day before operation,1d,3d and 7d after operation with Mini-mental state examination,and the postoperative cognitive dysfunction was recorded.Results The incidence of postoperative cognitive dysfunction was significantly lower in group II than in group I.The plasma cortisol concentration in group II after intubation was inhibited stronger than in group I(P 0.05).Conclusion Dexmedetomidine can prevent postoperative cognitive dysfunction in elderly patients by perioperative treatment,and the possible mechanism is related to reduction of cortisol level.