| General anesthesia has more than one hundred year history. It changes the function of central nervous system reversibly to achieve aponia, loss of consciousness, muscle relaxation, reflex inhibition by anesthetics or other way. This change needs to deteriorate immediately and has dexterous controllability. In all kinds of anesthesia, because of drugs used to general anesthesia safer, shorter action time and awake quicker, and enlargement of profession of anesthesia like anodynia artificial abortion and anodynia gastrointestinal endoscopy, general anesthesia makes a great advancement. General anesthesia accouts 58% in all kinds of anesthesia, and has a great of increase.Surgery trauma is an important reason of stress. How to inhibit stress response is important to anesthesia. Stress is non-specificity emotion response participated by nerves, endocrine, immunization and so on. Peri-analgesia and stress are producted when doctors drag internal organs. It can excite rennin-angiotensinamide-aldosterone system and hypothalamus-byophysis-adrenal cortex axis though nervous system. Anesthesia provides convenience for surgery operation and makes patient safe though inhibit stress, as it can interfere patients'physiological function. How to make patients safer during the peri-operative period is the aim of exploitation of drugs used to general anesthesia.Theory of adrenergic receptor introduced in 1948. Receptor which can combine with adrenalin and norepinephrine was named adrenergic receptor by researchers. It locates in cell envelope of effective apparatus dominated by postganglionic of sympathetic ganglion. Norepinephrine receptor contains a andβ. In 1974, Langer divited a norepinephrine receptor to two subgroups:α1 andα2, on the basis of anatomic site and physiologic functions. In 1988, Bylund et al, taked a2 subgroup to divide into four isomeride receptor,α2A,α2B,α2C andα2D. Clonidine, as a drug of a receptor agonist of norepinephrine, had used for powerful antihypertensive drug in the 70s. Now, a receptor agonist of norepinephrine is not only used to antihypertensive drug, but also used to amb-operation. Dexmedetomidine is one of high elective a2 receptor agonist of norepinephrine. Its electivity ofα2/α1 is 1620:1, while clonidine is 220:1. So dexmedetomidine can be considered to be a complete a2 receptor agonist. The main functions of dexmedetomidine are evident calm, hypnosis, analgesia and inhibition of activity by effecting on nucleus. It makes more and more attention in domain of anesthesia.Sevoflurane is a kind of new inhalation anesthetics. Blood gas distribution coefficient of sevoflurane is 0.62, induction quick, easy control of anesthesia depth. Fentanyl is powerful opioid anesthesia analgesic drug, stands up quickly, little interference to circulation. It used to clinical anesthesia, post-operation analgesia and acute angina pectoris widespread. Sevoflurane combine with fentanyl is common way to general anesthesia. Post-rout lumbar spinal fusion is most common lumbar vertebra surgery operation, lager surgical trauma, great degree of precision, long time consuming. This surgery requests well circulate oxygenation and stabilization of hemodynamics, and requests patients' analepsia quick to check nervous functions. The aim of this study is to determine the alveolar concentration of sevoflurane in body movement response to surgical incision during dexmedetomidine composite sevoflurane and fentanyl anesthesia; investigate the effects of dexmedetomidine on the hemodynamics and blood glucose responses to intubation and extubation; observe the effects of dexmedetomidine on the anesthesia recovery period; observe the analgesic effect of dexmedetomidine on postoperative pain relief.Objective: 1. To determine the alveolar concentration of sevoflurane in body movement response to surgical incision during dexmedetomidine composite sevoflurane and fentanyl anesthesia. 2. Investigate the effects of dexmedetomidine on the hemodynamics and blood glucose responses to intubation and extubation. 3. Observe the effects of dexmedetomidine on the anesthesia recovery period. 4. Observe the analgesic effect of dexmedetomidine on postoperative pain relief.Methods:This research contain two parts:(1) Determine EC50 (effective concentrations in 50%) and EC95 (effective concentrations in 95%) of sevoflurane in body movement response to surgical incision during Dexmedetomidine(DEX) composite sevoflurane and fentanyl anesthesia. Choose ASA I or II patients, aged 18-60 years old, underwent selective surgery for the treatment of lumbar discherniation under general anesthesia metioned above, were enrolled in this study. All patients received dexmedetomidine 0.5μg/kg infusion for 10min before the induction of anesthesia, and breathed 2～4L/min oxygen through a face mask at the same time, and then were induced by 8% sevoflurane and 3μg/kg fentanyl i.v.. At the loss of awareness, the sevoflurane was reduced to 5% relaxed. Anesthesia maintenance was performed by sevoflurane and dexmedetomidine 0.2μg·kg-1·-h-1. Before surgery operation, a steady state end-tidal sevoflurane concentration was maintained for at least lOmin. The first patient was tested at 1.5% sevoflurane. The concentration of sevoflurane was determined using the modified Dixon's up-and-down method (0.2% as a step size). Probit analysis was used for calculating EC50, EC95 and 95% confidence interval(CI). (2) To observe the effects of DEX on the hemodynamics and blood glucose responses to intubation and extubation; on the anesthesia recovery period and on postoperative pain relief. Sixty-five ASAⅠorⅡpatients, undergoing selective surgery for the treatment of lumbar discherniation under general anesthesia, were enrolled in this study. Patients were randomly assigned into five groups:The patients in group D0 are received intravenous injection of dexmedetomidine 0.0μg·kg-1·h-1 until to the end of the operation, group D1 0.2μg·kg-1·h-1, group D2 0.4μg·kg-1·h-1, group D3 0.6μg·kg-1·h-1, group D4 0.4μg·kg-1·h-1. Record changes of heart rate(HR) and mean arterial blood pressure(MAP) at the time of before administration(T1),after Dex or saline infusion(T2), after intubation(T3), intubation(T4),3min after intubation(T5), before extubation(T6), extubation(T7) and 3min after extubation(T8). Test preoperative fasting blood glucose (G1) and blood glucose concentration at the time of before intubation (G2), 10min after intubation (G3), before extubation (G4), and lOmin after extubation (G5). The time from termination of surgery to extubation and the time from termination of surgery to eye opening were recored. Record the score of Ramsay on patient at the time of termination of surgery to extubation and termination of surgery to eye opening. Postoperative analgesia efficacy was assessed by visual analog scales (VAS) at 1,2,4,8,12 and 24 h. Overall satisfaction to analgesic therapy were valuated and adverse effects were recorded during postoperative 24 h.Results (1) Determine EC50 (effective concentrations in 50%) and EC95 (effective concentrations in 95%) of sevoflurane in body movement response to surgical incision during Dexmedetomidine (DEX) composite sevoflurane and fentanyl anesthesia. The EC50 of sevoflurane was 0.94% (95%CI was 0.76%-1.07%) and EC95 of sevoflurane was 1.23%(95%CI was 1.09%-2.05%). (2) To observe the effects of DEX on the hemodynamics and blood glucose responses to intubation and extubatio; on the anesthesia recovery period and on postoperative pain relief.①Contrast to group D0, groups D1, D2, D3 and D4 HR and MAP are lower at T3, T5 and T7. Groups D2, D3 and D4 HR and MAP are lower at T8 than DO. Contrast to D0, groups D2, D3 and D4 G3 and G5 are lower.②Contrast to DO, spontaneously breathing recovery periods of groups D1, D2, D3 and D4 are shorter (P≤0.05). The time from termination of surgery to extubation of groups D2 and D3 are shorter than group D0 (P<0.05). The time from termination of surgery to eye opening of groups D2, D3, D4 are shorter than group D0 (P<0.05). Scores of Ramsay at 3 min after extubation of groups D1, D2, D3, D4 are lower than group DO (P<0.05). Scores of Ramsay at 3 min after eye opening of groups D1, D2, D3 are lower than group DO (P<0.05).③VAS score at postoperative 1,2,4,8,12 and 24h VAS score at postoperative 1,2,4,8 and 12h group Dl and group DO have no differences (P>0.05);VAS score at postoperative 1,2,4,8,12 and 24h group D2 and group D3 have no differences (P>0.05);VAS score at postoperative 24h group D3 and group D4 have no differences (P=0.207); VAS score at postoperative 1,2 and 4h groups D2, D3 and D4 are lower than groups DO and D1(P<0.05);VAS score at postoperative 8 and 12h, groups D2, D3 and D4 are lower than group DO (P<0.05), groups D3 and D4 are lower than group D1(P≤0.05); VAS score at postoperative24h groups D1, D2,D3 and D4 are lower than groups DO (P<0.05), groups D2,D3 and D4 are lower than groups D1 (P≤0.05).Compare to control group, incidence of nausea and vomit are lower in therapic groups (P≤0.05), but incidence of dry mouth are higher.Conclusions①The EC50 and EC95 of sevoflurane for preventing movement in response to surgical incision during sevoflurane composite dexmedetomidine and fentanyl anesthesia was 0.94% and 1.23%.②Dexmedetomidine attenuates the hemodynamic and blood glucose responses to intubation and extubation.③Dexmedetomidine can produce analgesic efficacy, improve overall satisfaction to analgesic therapy in dose-effect relationship. |
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