Influence Of Dexmedetomidine And Sub-anesthetic Dose Of Ketamine On Postoperative Delirium In Elderly Orthopedic Patients Under Total Intravenous Anesthesia

Objective：To investigate the incidence of postoperative deliriumafter using dexmedetomidine and sub-anesthetic dose of ketamine and toclarify their influence in the incidence of postoperative delirium in elderlyorthopedic patients under total intravenous anesthesia．Methods：One hundred and twenty elderly patients aged more than60years underwent elective orthopetic surgery， ASAⅠ-III， wererandomly divided into4groups（n=30）：normal saline（control group），ketamine group，dexmedetomidine group，ketamine+dexmedetomidinegroup．The patients in ketamine group received an intravenous injection ofketamine at a dosage of0.5mg kg-1．In dexmedetomidine group thepatients received dexmedetomidine at a dosage of1μg kg-1byintravenous injection before induction of anesthesia followed by acontinuous infusion at0.5μg·kg-1·h-1till30min before the end ofoperation．In ketamine+dexmedetomidine group，the patients receivedboth0.5mg kg-1ketamine and1.0μg kg-1dexmedetomidine over10minby intravenous injection followed by a continuous infusion ofdexmedetomidine at0.5μg·kg-1·h-1till30min before the end ofoperation．The patients in control group were administered with the sameamount of normal saline． The blood samples were taken before anesthesia，at the end ofoperation and24h after operation．The level of serum interleukin-6（IL-6） was detected using enzyme-linked immunosorbent assay（ELISA）．The Confusion Assessment Method（CAM）was applied toevaluate postoperative delirium1h，1d and3d after operation．Results：There were no statistical significance in age，gender，weight，operation time，anesthesia time，anesthesia dosage，bleeding，urine volume and infusion of the patients between four groups（P>0.05）．13patients in the study developed delirium：8patients in ketaminegroup（26.7%），2patients in dexmedetomidine group（6.7%），3patientsin control group （10%）， No delirium was found in ketamine+dexmedetomidine group．Compared with control group，the incidence rate of delirium inketamine group was increased significantly（P<0.05）．Compared withketamine group, the incidence rate of delirium in ketamine+dexmedetomidine group was decreased significantly (P<0.05)．There was no significant difference in serum IL-6levels of patientsbetween four groups (P>0.05)．Conclusion：when they are applied together，dexmedetomidinecould alleviate the side effects of ketamine and could decrease theincidence rate of delirium which mechanism is not responsible withinflammation．...