The Effects Of Dexmedetomidine On Postoperative Mechanical Pain Threshold And Cellular Immunity In Patients Undergoing Awake Craniotomy

ObjectiveIt is essential to search the suitable anesthesia which is use for awake craniotomy. In the preliminary reseach, we had found that Dexmedetomidine combined with propofol and reminfentanil for awake craniotomy were good for the recovery quality, haemodynamics, the location of electroencephalogram and so on. However, it has not been clear that the effect of this anesthesia on the factors influencing its postoperative outcome, such ashyperalgesia, the immune cells. So, this study observe the influence of Dexmedetomidine combined with propofol and reminfentanil on indicators such as quality of resuscitation, postoperative mechanical pain threshold, cellular immune function undering awake craniotomy, in order to identify whether Dexmedetomidine to meet the requirements of awake craniotomy also can improve the postoperative outcome, which can provide the good referential evidence for awake craniotomy.Methods60 patients ASA Ⅰ-Ⅱ undergoing awake craniotomy for the removal of brain tumor were included in this study. They were randomized into three groups accroding to the use of the sedative drugs during the lucid interval: Dexmedetomidine group (D group), the patients received Dexmedetomidine 0.2 μg·kg-1 more than 10min for the load, and given 0.2-0.4μg·kg-1·h-1 continuous infusion of dexmedetomidine until the end of surgery. General awake anesthesia group (R group), the patients in R group received propofol and remifentanil by target-controlled infusion, when remifentanil given 0.3-0.6 ng·ml-1 during the lucid interval. Control group(C group), the patients received normal saline infusion replaced Dexmedetomidine. Anesthesia was induced with remifentanil and propofol which were both given by TCI system simultaneously and Narcotrend. Mechanical pain thresholds on the contralateral forearm and operiative incisional area were measured by von Frey filament. Mechanical pain thresholds were recorded before surgery, and at 24h, 48h,72 hours postoperation, additional the hemodynamic and blood gas analysis in the operation and VAS scoreblood, the postoperative adverse reactions within 72h were recorded. Venous blood samples were collected at the following times:before induction of anesthesia(TO), immediately after termination of operation(T1),24h(T2) and 48h(T3)after the end of operation. The blood samples were collected for determination of the expression of CD3+、CD4+、 CD8+on T-lymphocyte and CD16+/56+/45 on natural killer cells by flow cytometry and calculation of proportion of CD4+and CD8+.Results1. The OAA/S were 5 in awaken period of all groups. There was no statistical significance on the hemodynamics, blood gas analysis, the quality of awaken and the incidence of adverse reactions of the three groups (P>0.05)2. Compared Mechanical pain thresholds on forearm with the preoperative, it is significantly decreased on mechanical pain thresholds in three group (P <0.05). Mechanical pain thresholds in group D are higher at 24h,48h,72h postoperatively compared with the group R and the group C (P<0.05). There was no significant difference between R group and C group(P>0.05) at 24h, 48h,72h postoperatively. The change in pain threshold on the peri-incisional area was similar among the groups.3. All of the percentage of CD3+、CD4+、CD8+ on T-lymphocyte immediate, 24 and 72h post-operation were lower than before surgery among the there group(P<0.05). There were no significant differences in three groups of patients with CD8+(P>0.05). The the percentage of T cell subpopulations and NK cells at immediate,24h,48h post-operation were lower in R and C group than that D group(P<0.05). NK cells of all group are higher at immediabte post-operantion. There was no significant difference between R group and C group(P>0.05) at 24h,48h,72h postoperatively.Conclusion1. Dexmedetomidine can be successfully applied to awake craniotomy, which have a lot of advantages with stable hemodynamics, less respiratory depression, without prejudice to the postoperative complications, the good quality of recovery from anesthesia.2. The application of Dexmedetomidine in awake craniotomy can reduce the impact on the postoperative mechanical pain threshold, which can prevent postoperative hyperalgesia.3. The application of Dexmedetomidine in awake craniotomy can improve immunologic function of T lymphocytes, which can relieve the inhibition of cellular immunity function of their bodies.