小剂量右美托咪啶复合芬太尼时七氟烷最低肺泡有效浓度的测定

Measurement of the minimum alveolar concentration of sevoflurane during combined anesthesia with sevoflurane,small-dose dexmedetomidine and fentanyl

目的测定复合右美托咪啶和芬太尼时七氟烷抑制切皮体动反应的呼气末肺泡50%有效浓度(effective concentra-tions in 50%,EC50)和95%有效浓度(EC95)。方法选择ASA Ⅰ或Ⅱ级,年龄18～60岁腰椎后路融合手术病人,输注右美托咪啶0.5 mg/kg后8%七氟烷和芬太尼3 mg/kg诱导,病人意识消失后七氟烷浓度降至5%,同时给琥珀胆碱1～2 mg/kg肌松人后的行呼气末管七内氟插烷管浓。度七为氟1.烷5%和。右七美氟托烷咪最啶低0肺.2泡mg有(/效kg.浓h)度维(M持A麻C醉)按,七改氟良烷序呼贯气法末增浓加度或稳减定少100.2m%in。后用开概始率手单术位。回第归1法个病计算七氟烷抑制切皮反应的EC50、EC95及相应的95%可性区间(CI)。结果七氟烷抑制切皮体动反应的EC50为0.94%,95%CI为0.76%～1.07%;EC95为1.23%,95%CI为1.09%～2.05%。结论复合小剂量右美托咪啶和芬太尼时,七氟烷抑制切皮体动反应EC50为0.94%和EC95为1.23%。

Objective To determine the minimum alveolar concentration（EC50 and EC95） of sevoflurane in body movement response to surgical incision during combined anesthesia with dexmedetomidine,sevoflurane and fentanyl.Methods Twenty-six ASA class Ⅰ or Ⅱ patients（aged 18-60 years） underwent selective surgery for lumbar disc herniation under general anesthesia with the combination of with dexmedetomidine,sevoflurane and fentanyl.All the patients received infusion with 0.5 mg/kg dexmedetomidine for 10 min before anesthesia induction with intravenous injection of 3 μg/kg fentanyl 8% sevoflurane inhalation.Upon loss of consciousness,sevoflurane concentration was reduced to 5% with intravenous injection of 1-2 mg/kg succinylcholine,and intubation was started after muscles relaxation.Anesthesia was maintained by sevoflurane and dexmedetomidine（0.2 μg·kg-1·h-1）.Before the surgery,a steady state end-tidal sevoflurane concentration was maintained for at least 10 min.The first patient of the series was tested with 1.5% sevoflurane,and the concentration was adjusted according to modified Dixon＇s up-and-down method（with a step size of 0.2%）.Probit analysis was used for calculating EC50,EC95 and the 95% confidence interval（CI）.Results The EC50 of sevoflurane was 0.94%（95%CI of 0.76%-1.07%） and EC95 was 1.23%（95%CI 1.09%-2.05%）.Conclusion The EC50 and EC95 of sevoflurane are 0.94% and 1.23%,respectively,for suppressing body movement in response to surgical incision during combined anesthesia with sevoflurane,dexmedetomidine and fentanyl.