新生儿七氟烷最低肺泡有效浓度

Minimum alveolar concentration of sevoflurane in neonates

目的确定新生儿七氟烷的最低肺泡有效浓度（MAC）。方法择期全麻新生儿30例，正常体重，ASA分级I或Ⅱ级。吸入6．00％七氟烷诱导气管插管，机械通气后调整吸入七氟烷浓度以达到呼气末浓度的预定值，维持20rain后开始切皮。根据改良序贯法进行试验，初始七氟烷呼气末浓度为3．00％，切皮时发生体动反应，下一例升高一个浓度梯度，切皮时未发生体动反应，下一例降低一个浓度梯度，相邻浓度梯度为0．25％。采用逻辑回归法计算新生儿七氟烷MAC和95％有效浓度及其95％可信区间。结果新生儿七氟烷MAC和95％有效浓度及其95％可信区间分别为2．82％（2．66％～2．98％）和3．39％（2．89％～3．89％）。结论国内新生儿七氟烷MAC为2．82％，低于目前国外参考值。

Objective To determine the minimum alveolar concentration （MAC） of sevoflurane in Chi- nese neonates. Methods Thirty ASA Ⅰ or Ⅱ neonates, aged ≤ 28 days, with normal body weight, scheduled for elective surgery under general anesthesia, were enrolled in the study. Anesthesia was induced with inhalation of 6.00% sevoflurane in oxygen. The infants were tracheal intubated and mechanically ventilated. The inhaled con- centration of sevoflurane was adjusted to achieve the preset end-tidal concentration and maintained at this level for 20 min. Skin incision was then performed. The concentration of sevoflurane was determined by modified Dixon＇s up-and-down method. The initial end-tidal concentration of sevofluren was 3.00%. Each time the concentration increased/decreased by 0.25 % in the next infant according to the infant＇s response. Successful skin incision was defined as no body movement during skin incision. The MAC, ED95 and 95 % confidence interval of sevoflurane were calculated using logistic regression analysis. Results The MAC and ED95 （95 % confidence interval ） of sevoflurane required for successful skin incision were 2.82% （2.66%-2.98%） and 3.39% （2.89%-3.89%）, respectively, in neonates. Conclusion The MAC of sevoflurane is 2.82 % in Chinese neonates and lower than the present reference values previously described in foreign reports.