骶管阻滞对小儿喉罩拔除七氟烷最低肺泡有效浓度的影响

Caudal block reduces the minimum alveolar concentration of sevoflurane for laryngeal mask airway removal in children

Sevoflurane目的：评价单次骶管阻滞对患儿拔除喉罩七氟烷最低肺泡有效浓度（MACLMA）的影响。方法选择2012年1～12月在四川省简阳市中医医院择期行单侧腹股沟斜疝手术患儿50例为研究对象，年龄2～5岁，美国麻醉医师协会分级为Ⅰ级，按照计算机生成的随机种子表将其随机分为七氟烷全身麻醉＋骶管阻滞组（研究组）和七氟烷全身麻醉组（对照组），两组均为25例。研究组行单次骶管阻滞（0.25%罗哌卡因1 ml/kg）；对照组未行骶管阻滞。两组患儿均采用七氟烷吸入诱导并维持，喉罩维持自主呼吸的麻醉方法。根据Dixon序贯法确定MACLMA。Probit概率单位法确定50%和95%患儿拔除喉罩七氟烷肺泡有效浓度（EC50和EC95）。结果两组患儿年龄、体质量等一般临床资料比较，差异无统计学意义（P＞0.05）。研究组患儿拔除喉罩的七氟烷EC50值为1.21%（95%CI 1.14%～1.31%），EC95值为1.56%（95%CI 1.39%～2.14%）；对照组患儿拔除喉罩的七氟烷EC50值为1.78%（95%CI 1.63%～1.87%），EC95值为2.21%（95%CI 1.96%～2.87%）。研究组患儿喉罩拔除七氟烷EC50和EC95均低于对照组，差异有统计学意义（P＜0.001）。单次骶管阻滞后，患儿拔除喉罩的七氟烷EC50和EC95值分别下降了32.1%和29.4%。结论骶管阻滞可降低小儿喉罩拔除七氟烷最低肺泡有效浓度。

Objective The present study was designed to evaluate the minimum alveolar concentration of sevoflurane for Laryngeal mask airway removal （MACLMA） with and without caudal block in children. Methods A total of 50 subjects between 2 and 5 years old, American Society of Anesthesiologists physical statusⅠ, who were undergoing unilateral oblique inguinal hernia repair from January 2012 to December 2012 in Jianyang Integrated Traditional Chinese Medicine Hospital. Subjects were allocated to receive or not to receive caudal block according to random list generated by a computer. General anaesthesia was induction and maintain with sevoflurane via laryngeal mask airway. The MACLMA of sevoflurane for a smooth LMA removal with and without caudal block were evaluated by the Dixon up-and-down method. A LMA removal accomplished without coughing, teeth clenching, gross purposeful movement, breath holding or laryngospasm, during or within 1 min after removal was considered to be successful. The study protocol was approved by the Ethical Review Board of Investigation in Human Beings of Jianyang Integrated Traditional Chinese Medicine Hospital. Informed consent was obtained from the parents of each participating patient. Results The age, body mass, duration of anesthesia and surgery of two groups had no significant difference（P〉0.05）. The EC50 and EC95 of sevoflurane to achieve successful LMA removal in children with caudal block were 1.21%and 1.56%, respectively. The EC50 and EC95 of sevoflurane to achieve successful LMA removal in children without caudal block were 1.78%and 2.21%, respectively. The EC50 and EC95 values of sevoflurane for LMA removal significantly different between the two groups （P＆lt;0.001）. The EC50 and EC95 values of sevoflurane for LMA removal were reduced by 32.1% and 29.4%, respectively. Conclusion Caudal block significantly reduced the sevoflurane concentration for a smooth LMA removal in children.