右美托咪定降低小儿Ambu AuraOnce喉罩置入所需七氟醚呼气末半数有效浓度

Dexmedetomidine reduces end-tidal sevoflurane median effective concentration value for Ambu AuraOnce laryngeal mask insertion in children

目的 观察右美托咪定（dexmedetomidine,Dex）1μg/kg降低小儿Ambu AuraOnce喉罩（Ambu喉罩）置入所需七氟醚呼气末半数有效浓度（median effective concentration,EC50）作用. 方法 4～10岁全身麻醉下行择期整形外科手术患儿50例,ASA分级Ⅰ级,计算机随机抽样表格法分为Dex组（D组,26例）和对照组（C组,24例）.患儿入室后均采用8％七氟醚和50％氧化亚氮（nitrous oxide,N2O）吸入行麻醉诱导,建立静脉通路后停止N2O吸入,调节七氟醚吸入浓度使七氟醚呼气末EC50达到预定浓度.同时D组开始静脉输注Dex 1 μg/kg,C组注射生理盐水,10 min注射完毕后置入一次性Ambu喉罩.两组首例患儿的七氟醚呼气末EC50均设定为1.8％,采用改良Dixon up-down法确定下一例喉罩置入的七氟醚呼气末EC50,相邻七氟醚的浓度梯度值为0.2％. 结果 小儿置入Ambu喉罩时所需七氟醚呼气末EC50值（95％CI）D组和C组分别为1.44％（1.17％,1.60％）和1.77％（1.52％,2.01％）. 结论 Dex 1 μg/kg可有效降低小儿置入Ambu喉罩所需七氟醚呼气末EC50.

Objective Investigation the effect of dexmedetomidine （Dex） on the end-tidal concentration of sevoflurane at which 50%[median effective concentration （EC50）] of the attempts to insert the Ambu AuraOnce （Ambu） laryngeal mask would be successful.Methods 50 patients of ASA physical status Ⅰ,aged 4-10 years,undergoing plastic surgery with general anesthesia were randomly divided to the group Dex（group D） and the controlled group（group C）.Anesthesia was induced with sevoflurane 8% in a mixture of nitrous oxide （N2O） 50% and oxygen 50%.After intravenous cannula was placed,N2O was discontinued and inhalation concentration of sevoflurane was modified to reach predetermined end-tidal concentration of sevoflurane.In group D,Dex 1 μg/kg was infused for 10 min.In group C,0.9% sodium chloride solution was infused.10 min later,Ambu laryngeal mask was inserted in both groups.For the first patient in group D and in group C,the end-tidal concentration of sevoflurane was designed at 1.8%.Using modified Dixon＇s up-down method,the target end-tidal concentration of sevoflurane for the next patient was determined with increment size of 0.2%.Results The values of sevoflurane required for successful insertions of Ambu laryngeal mask in group D and in group C were 1.44%（1.17%,1.60%） and 1.77%（1.52%,2.01%） respectively.Conclusions Dex 1 μg/kg reduces the value of EC50 of sevoflurane for insertion of Ambu AuraOnce laryngeal mask airway in children.