| Background and ObjectiveDexmedetomidine belongs to one of the imidazoles derivatives, dextral isomerof medetomidine, is a new type of high selective alpha2adrenergic agonists. It hassedative, analgesic, anti-anxiety, hypnosis, and the sympathetic nerve inhibition roles.The latest research shows that dexmedetomidine also has certain anti-inflammatoryand anti-stress effect. It can maintain hemodynamic stability, a certain protectiveeffect on brain, kidney and other organs function, but has no effects on respiration. In1999, dexmedetomidine was approved by the Food and Drug Administration (FDA)to promote sedation in intensive care units (ICUs) for the mechanical ventilationpatients, since then the unique pharmacological properties of dexmedetomidine; it hasbeen widely used in clinical practice in the many countries.Recently, several studies of domestic and abroad have shown that,dexmedetomidine can inhibit stress reaction, maintain hemodynamic stability, reducethe stimulation during extubation and reduce postoperative agitation. It also canpreserve intracranial homeostasis, fast transit from sleep to awake, and facilitatesneurological evaluation even in the operating room, by reducing cerebral blood flow （which improves the relationship between oxygen supply and demand）。These arethe beneficial effects for neurosurgery patients so, dexmedetomidine, has also beenwidely used in neurosurgery.In recent years, some studies on sedated dog with dexmedetomidine, haveshown that: a significantly rise blood sugar, inhibit the release of insulin, increase theplasma concentration of lactic acid, reduce plasma cortisol concentration. Theseeffects of dexmedetomidine are unfavorable for neurosurgery patients:Hyperglycemia can cause changes in plasma osmotic pressure, further affect themorphology and function of tissues and cells, damage body tissues and organs byinhibited the immune, increased proinflammatory cytokine, damaged the function ofmitochondrial and increase the production of oxygen free radicals. Perioperativehyperglycemia can cause deterioration of most types of brain ischemia, and damageto vascular endothelial cells has been confirmed. Lactic acid as metabolic product ofglycolysis, has long been regarded as the markers of ischemia, hypoxia or damage incentral nervous system. Cortisol is one kind of steroid hormones, is one of trademarkproducts of the stress response, and has the important role of regulate the body’sinternal environment.For the neurosurgery, because of its fineness degree of operation a deep depthof anesthesia is often required in these operations. The depth of anesthesia too deep ortoo shallow will be unfavorable for patients. With the combined application of newmuscle relaxant, sedative and analgesic agents, the depth of general anesthesia andconscious level are often covered up or difficult to identify. So, controlling andestimating relatively appropriate depth of anesthesia has become a clinical problemwhich necessary to be solved. NT index (Narcotrend Index) is a new great potentialmonitoring method depth of anesthesia. Due to the electrode position there is nospecial requirement, and real-time monitor, all of these determine and can be used inneurosurgical patients.At present, the research about the impaction on the NT index ofdexmedetomidine has been found very few; and the study of its effect on bloodglucose, insulin, cortisol and lactic acid were also deficient nationally andinternationally. This study focuses on the impaction of different dose of dexmedetomdine on the NT index、insulin、cortisol and lactic acid, to provide clinicalfoundation for the rational administration.Material and MethodSelect60patients undergoing for elective neuroma resection under generalanesthesia, aged from30to60years, the class of ASAⅠ～Ⅱ, weight from50to80kg, using the random number table method, randomly divided them into three groups:group C (control group), the group D1(group Dex0.3μg/kg/h), group D2(groupDex0.5μg/kg/h),20cases in each group.Anesthesia induction: In the group D1,10minutes prior to anesthesia induction,we gave dexmeetomidine0.3μg/kg through continuous intravenous infusion bymicro-pump, then at the speed of0.3μg/kg/h. In the group D2,10minutes beforeanesthesia induction, we gave dexmeetomidine0.5μg/kg through continuousintravenous infusion by micro-pump, then at the speed of0.5μg/kg/h. Weadministered equal strength of physiological saline in group C. Unlock propofol TCIinfusion pump after the loading dosage are pumped, carried out in accordance withthe method of sequential plasma target controlled infusion. After all patients’ NTindex dropped to35%in three groups, intravenous fentanyl4ug/kg, cis-atracurium0.2mg/kg, manual ventilation till the muscle were relaxed completely, then trachealintubation by direct laryngoscopy. Anesthesia maintenance: propofol TCI andremifentanyl0.2μg/(kg·min) by continuous intravenous infusion, monitor andmaintain the NT index during30-40%, and discontinuously administer cis-atracurium0.07mg/kg to maintain muscle relaxantion, routine analgesia after operation wereprovided to every patients.Observe and record of patients’ systolic blood pressure (SBP), diastolic bloodpressure (DBP), mean arterial pressure (MBP), heart rate (HR), pulse oxygensaturation (SPO2), Narcotrend Index (NT index), and end-tidal CO2pressures (PETCO2)at seven time points, which respectively are in the operating room just（T0）、beforeendotracheal intubation (T1), immediately after endotracheal intubation (T2),3minutes after endotracheal intubation (T3),1hour after surgery (T4),2hours after surgery (T5), at the end of surgery(T6). We determined the arterial blood gas at theseven time points mentioned above in each group, to detect the content of bloodglucose and lactic acid, and we also extract central venous blood3ml, injected intoanticoagulant tubes, centrifuging for15minutes under the conditions of4℃and3000r/min, then return the supernatant into EP tube, and finally preserved them inthe–80℃cryogenic refrigerator for the future use. We analyzed the concentration ofplasma insulin (Ins), cortisol (Cor) by using enzyme-linked immunosorbent (ELISA).We use the software of SPSS17.0for statistical analysis, and express thequantitative data by mean±standard deviation(x±s), analyze the qualitative databy t-test or corrected t-test、chi-square test, use the single factor analysis of varianceand repeated measurements for the comparison of Multiple sets of quantitative data.Significant level: α=0.05.Results1. The comparison of general information of the three groups.There was no statistical significance by comparing patients’ age, weight, genderand duration of operation among the three groups(p＞0.05).2. The comparison of NT index at different time point of the three groups.Compared with group C, the NT index of group D1、D2at the time point T2(immediately after endotracheal intubation)are significantly lower, and the differencewere statistically significiant(p＜0.05).3. The comparison of target concentration of propofol in three groups.Compared with group C, patient’s target concentration of propofol in group D1and group D2when the NT index dropped to35%was low, and the difference wasstatistically significant (p <0.05). patient’s target concentration of propofol in groupD2was lower than group D1, and the difference was statistically significant (p <0.05).4. The comparison of intraoperative vital signs of the three groups.Compared with time-point T0, MAP、SBP、DBP and HR in the three groups werelower at time-point T1、T4、T5, and the difference was statistically significant(p＜0.05), in group C, MAP、SBP and DBP were more higher, and the difference wasstatistically significant(p＜0.05). But the difference of SPO2in the three groups atany time-point has no statistical significance by comparing with T0(p＞0.05). Thedifference of basic MAP、SBP、DBP、HR、SPO2among the three groups is notstatistically significant(p＞0.05). Compared with group C, the MAP、SBP、DBP andHR of group D1、D2at the time-point T2and T3were lower, and the difference wasstatistically significiant(p＜0.05).5. The comparison of blood glucose、insulin、cortisol and lactic acid of the threegroups.In group C、D1、D2，the difference of blood glucose、insulin、cortisol and lacticacid has no statistical significance respectively at any time point between and withingroups(p＞0.05)．Conclution1. Dexmedetomidine can reduce the induced target plasma concentration of propofol,and is related to the dose of dexmedetomidine．2. Dexmedetomidine can inhibit stress response in a certain degree, maintainhemodynamic stability and NT index of patients during operation．3. Dexmedetomidine does not decrease the amount of insulin release, and does notincrease the concentration of intraoperative blood glucose, and influence theconcentration of cortisol and lactic acid slightly．... |
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