| Objective:To intervene elderly patients who are undergoing total knee arthroplasty?TKA?with different doses of dexmedetomidine and use flow cytometry to analyze peripheral blood lymphocyte subsets expressions at different point among perioperative period.We will argue the possibilities of dexmedetomidine playing protective role in cellular immunity,the effectiveness of reducing immune suppression and explore the best dose of dexmedetomidine for immune protection.Methods:Select the elderly patients undergoing subarachnoid block for total knee arthroplasty?TKA?,signing an informed consent,in accordance the selected object standards and combined the exclusion criteria,60 patients were randomly,depending on the dose of dexmedetomidine,divided into three groups:the high-dose group?group Dl?,the isodose group?group D2?and the low-dose group?group D3?with 20 cases in each.After subarachnoid block,all three groups were infused with 0.5ug/kg first loading dose of intravenous bolus administration in 10 minutes,then pumped a maintenance infusion of0.70?g/?kg·h?,0.33?g/?kg·h?and 0.17?g/?kg·h?respectively in group D1,group D2 and group D3.Flow cytometry was used to detect levels of various lymphocyte subsets including lymphocytes,CD3+,CD4+,CD8+,CD4+/CD8+,CD69+,CD3+/CD69+and Treg at three different time point including five minute after subarachnoid block,five minute after surgery and twenty-four hours after surgery.The adverse events during surgery and complications after operation were also been recorded.Results:There were no statistically significant differences among three groups in the levels of age,gender,height,weight,DBP,SBP,HR,volume of fluid input,blood loss,and lymphocyte,CD4+,CD8+,CD4+/CD8+,CD3+,CD69+,CD3/CD69 and Treg cell at five minute after spinal anesthesia?p>0.05?.Compared with the time point before operation started,,the amount of lymphocyte and CD8+evidently lower at 5 minutes after operation and the amount of lymphocyte,CD4+,CD8+,CD3+were all apparently lower at 24h after operation.The CD69 and Treg were significantly higher at both two point.5 minutes after operation,the amount of lymphocyte,CD3+and CD4+/CD8+in high-dose group were higher than that in low-dose group?p<0.05?.24h after operation,the amount of lymphocyte,CD4+,CD4+/CD8+,CD3+,CD69+in high-dose group and isodose group were all apparently higher than that in low-dose group?p<0.05?.Treg in high-dose group were significantly lower than low-dose group both at 5 minutes after operation and 24h after operation.In the three groups,8 patients complained of dry during operation,and 6had transient hypertension,8 had a 30%decrease of blood pressure compared with basic value.6 people have a bradycardia,and no arrhythmia occurred during the three groups.After operation,6 were nausea,2 were vomiting,3 were drowsiness,and 1 were hypoxemia.Conclusion:?1?The total number of lymphocytes,T lymphocytes,helper T lymphocytes and cytotoxic T lymphocytes in TKA surgery decreased significantly after surgery,although the time of occurrence had been different.?2?Dexmedetomidine in high-dose group and isodose group have a protective effect on the total number of T lymphocytes,T lymphocytes,helper T lymphocytes and cytotoxic T lymphocytes.?3?Dexmedetomidine in high-dose group and isodose group can constraint the increase of Treg cells after surgery and clearly reduce the immune suppression caused by Treg cells compared with low-dose group.?4?Although The incidences of a transient increase in blood pressure,hypotension and sinus bradycardia are higher in high-dose group than the other two groups,dexmedetomidine has less effect on postoperative complications.?5?Choose a moderate dose of dexmedetomidine?Maintenance dose>0.33?g/?kg·h?and<0.7?g/?kg·h??can both provide a more adequate immune protection in the perioperative period and reduce the incidence of adverse events during operation,it is a nice choice for perioperative applications in TKA. |
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