A Study Of The Neuroprotection Of Dexmedetomidine In Patients Undergoing Roofing Of Temporal Muscle In The Treatment Of Moyamoya Disease

Objective: To study the effects and the neuroprotection mechanism of dexmedetomidine in hemodynamics, intracranial metabolism of oxygen on patients undergoing roofing of temporal muscle in the treatment of Moyamoya disease.Methods: Sixty patients(weight 51~86kg, height 158~186cm, and ASA status II ~ III) were selected. They were randomly assigned into two groups: dexmedetomidine group(group D, n=30,average age: 56.00±5.05) and saline group(group S,n=30, average age: 57.70±4.29). The patients were given atropine 0.5 mg im before operation. Dexmedetomidine(0.6μg?kg-1) and same dose of 0.9% saline were administrated 10 minutes before anesthesia induction. In group D, dexmedetomidine were infused persistently by the rate of 0.4μg?kg-1?h-1 while in group S saline were administrated by the same rate. Anesthesia induction began with intravenous administration of midazolam(0.05mg?kg-1). Propofol(3.00μg?L-1) and remifentanil(4.00ng?L-1) target controlled infusion(TCI) were administrated by Orchestra anesthesia working station. Tracheal intubation was followed by cisatracurium besilate intravenous injection. The patient’s index of hemodynamics(heart rate and mean artery pressure) was recorded at different time points including before administration of dexmedetomidine or saline(T0), before endotracheal intubation(T1), 10 minutes after intubation(T2), skin incision(T3), opening the dura mater(T4), roofing the temporal muscle(T5) and occluding the dura mater(T6), before extubation(T7), 10 minutes after extubation(T8). Total dosage of propofol and remifentanil, postoperational recovery status, adverse events including coughing, dysphoria after extubation, postoperational shivering, recovery time of awaking and time of extubation were also recorded respectively. 3ml blood sample were taken respectively from radial artery and internal jugular vein at before administration of dexmedetomidine or saline(T0), before endotracheal intubation(T1), 10 min after endotracheal intubation(T2), skin incision(T3), opening the dura mater(T4), roofing the temporal muscle(T5) and occluding the dura mater(T6) for blood gas analysis(ABL90 blood gas analyzer) to determine the arterio-venous oxygen content difference(Da-jv O2) and cerebral oxygen extraction rate(CERO2). Ca O2 and Cjv O2 were also recorded, then Da-jv O2 and CERO2 were calculated by Fick formula. 3ml blood sample were taken from peripheral veins before introduction, at the moment of finishing the operation and 24 h after operation, kept with non-anticoagulation tubes. Centrifuged the supernatant(3500r/min for 10 minutes) after the serum separating out completely and stored in the refrigerator(-70°C) for test. Malondialdehyde(MDA) concentration was measured by thiobarbituric acid colorimetry method, serum glutamine level was measured by enzyme linked immunosorbent assay(ELISA).Result: 1. There were no significant differences in the general datas between the two groups.2. Indexes of hemodynamics. Compared with T0, MAP decreased at T1 in group D(P<0.5); compared with T1, HR and MAP increased significantly at T2 in group S(P<0.5). Compared with T7, HR and MAP increased significantly at T8 in group S(P<0.5).Comparing the MAP and HR between groups, MAP and HR in group D decreased at T1, T2, T7, T8 compared with group S(P<0.5); HR and MAP showed no significant differences between group D and group S at T4, T5, T6(P<0.5).3. Indexes of cerebral oxygen metabolism. Da-VO2 and CERO2 at T0 showed no significant differences in both group D and group S(P<0.05);Compared with T0, Da-VO2 and CERO2 decreased at T1~T6 in group D(P<0.05), Da-VO2 and CERO2 increased at T2, T3 in group S(P<0.05). Compared with group S, Da-VO2 and CERO2 decreased at T1~T6 in group D(P<0.05).4. Indexes of neuroprotection. Glutamine level of peripheral blood increased in both group D and group S when the operation was finished(P<0.05) while glutamine level of patients in group S was higher than glutamine level of patients in group D(P<0.05). Compared with preoperative peripheral glutamine and MDA level, level of these two indexes of patients in group D at 24 h after operation showed no significant diference(P>0.05)while in group S, it was still higher than that preoperatively(P>0.05).Conclusion: Dexmedetomidine administration combined with propofol and remifentanil TCI perioperatively in patients undergoing elective roofing of temporal muscleinthe treatment of Moyamoya disease(BIS 45~60 during the operation): Compared with group S, patients in group D maintained more stable hemodynamic status during the operation, fewer total consumption of the anesthetic drugs and lower risks of adverse reaction during the anesthesia resuscitation.(1) Compared with group S, patients in group D gained lower cerebral metabolic rate so that the oxygen supply and demand of the brain could be more balanced.(2) The level of glutamine in peripheral blood of patients in group D was significantly decreased than patients in group S. Level of MDA of patients in group D recovered normally at the first day after the operation which was significantly lower than than in group S.