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

Objective To observe the influence of the sub-anesthetic doses of ketamineand dexmedetomidine on early postoperative cognitive dysfunction（POCD）underwent orthopedic surgery in elderly patients，and to clarify its relatedmechanism． Methods120patients aged60years underwent electiveorthopedic surgery were randomly divided into ketamine group，dexmedetomidine group，ketamine＋dexmedetomidine group and the controlgroup，30cases in each group． All patients received total intravenousanesthesia．Before anesthesia，the patients in ketamine group received0.5mg kg-1ketamine intravenous injection．The patients in dexmedetomidinegroup received infusion of dexmedetomidine1μg kg^-1at first，followed by the0.5μg kg^-1 h^-1infusion until30minutes before the end of operation．Thepatients in ketamine＋dexmedetomidine group received intravenous infusion ofketamine and dextromethorphan．The patients in control group intravenousinfusion of saline．The Mini Mental State Examination （MMSE） was used toassess cognitive function1d before operation and1，7d after operation．Theincidence of POCD was recorded．Blood samples were taken before anesthesiainduction，at the end of operation and24h after the operation for determination of IL-6．Results Compared with control group，the time from consciousnessto extubation of the patients in dexmedetomidine group was singnificantlprolonged（P <0.05）．The incidence of POCD were26.7%and13.3%incontrol group at1，7d after operation，ketamine group，6.7%and0in ketaminegroup，20.0%and10.0%in dexmedetomidine group，13.3%and3.3%inketamine＋dexmedetomidine group．Comparing with the control group，theincidence of POCD in ketamine group at1，7d after operation were significantdecreased （P <0.05），the incidence of POCD in dexmedetomidine group andketamine＋dexmedetomidine group at1，7d after operation had nosignificant differences （P>0.05）．The serum IL-6levels had no significantdifference between various groups （P<0.05）．Conclusion The application ofsub-anesthetic dose of ketamine can reduce the incidence of early POCD inorthopedic surgery．Dexmedetomidine alone or combined with ketamine cannot reduce the incidence of early POCD in orthopedic surgery．The occurrenceof POCD has nothing to do with inflammatory reaction．...