Effect Of Dexmedetomidine On Postoperative Cognitive Dysfunction And Expression Of HMGB1 And RAGE In Peripheral Blood In Elderly Patients

?Objective? To explore the effects of Dexmedetomidine(DEX)on change of postoperative cognitive function in elderly patients with total knee arthroplasty under combined spinal epidural anesthesia(CSEA),and the expression of High Mobility Group Protein B1(HMGB1)and the Receptor of Advanced receptor Glycation Endproducts(RAGE)in peripheral blood.?Methods? 80 cases of total knee replacement in Qingdao municipal hospital from April to November in 2016 were collected,the age range 65-75 years old,ASA grade from II to III,were randomly divided into 2 groups: control group(group C,n=40)and dexmedetomidine group(group D,n=40).After completion of combined spinal epidural anesthesia and femoral nerve puncture catheter by ultra-sound,group D received intravenous infusion of dexmedetomidine at a loading dose of 0.5 ug/kg,with a pump time of 15 min,and then pump at the rate of 0.5ug/kg?h to the end of operation.Group C was given equal volume of physiological saline.Peripheral venous blood was gathered before anesthesia(T0),1 d(T1)and 3 d(T2)after surgery.The concentration of HMGB1 in plasma was determined by ELISA method,and the expression level of RAGEm RNA and HMGB1 m RNA in peripheral blood mononuclear cells(PBMC)was determined by RT-PCR.The heart rate(HR)and mean arterial pressure(MAP)were recorded in two groups of patients at T0,Intravenous injection pump 10 min(T(1)),20 min(T(2)),and end of the surgery(T(3)).The patients were tested by neuropsychological tests at l d before operation,7 d after operation and 1 months after operation.The Z scoring method recommended by ISPOCD was used to determine whether the patient had POCD.?Results?(1)In group C and group D,the incidence of postoperative 7 d POCD was32.5% and 12.5% respectively,the incidence of POCD in group C was higher than that in group D(P<0.05),and there was no significant difference between two groups after 1month(P>0.05).(2)Compared with group C,plasma concentration of HMGB1 in group D at T1 and T2(628.67±183.43 vs 880.03±216.33 pg/ml,506.37±160.67 vs 700.14±185.43 pg/ml)was reduced(P<0.05);(3)the expression level of HMGB1 m RNA at T1 and T2 in group D(0.0035±0.0009,0.00074±0.00024)was significantly lower compared with group C(0.0314±0.0096,0.00423±0.00075)(P<0.05);meanwhile,the expression level of RAGEm RNA at T1 and T2 in group D(0.00093±0.00014,0.00009±0.000009)was depressed than that in group C(0.00746±0.00419,0.00041±0.0001373)(P<0.05).(4)Two groups of patients at T0,T(1),T(2)and T(3)the mean arterial pressure(MAP)change was not statistically significant(P>0.05);while,group D at T(1)and T(2),the heart rate(HR)was lower than that in group C with statistical significance(P<0.05).?Conclusion? Dexmedetomidine can decrease the recent incidence of POCD in elderly patients.The mechanism may be related to the inhibition of the expression of HMGB1 and RAGE in peripheral blood and the reduction of inflammatory response.