Comparison of Rapid Inhalation Induction with Sevoflurane, Isoflurane and Halothane in Children<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

邓晓明　主任医师　Xiaoming Deng
肖文静　Wenjing Xiao
唐耿志　Genzhi Tanget

中国医学科学院　中国协和医院大学　整行外科医院麻醉科，北京 100041

Department of Anesthediology, Plastic Surgery Hospital. The Chinese Academy of Medical Sciences, Beijing Union Medical University, Beijing 100041，China.

Abstract

　　Objective：To observe the effect of rapid inhalation induction with sevoflurane, isoflurane and halothane with nitrous oxide（N₂O）. Methods Fifty eight unpremedicated children（ASA I）, 4～11 years of age, were divided randomly into three groups. Group S（n=20） received 5% sevoflurane with 60% N₂O; Group I（n=18） received 3.5% isoflurane with 60% N₂O; Group H（n=20） received 2% halothane with 60% N₂O. Elapsed time intervals from face mask application to loss of the eyelash reflex and loss of movement to pinpuncture were measured respectively. The irritant effect on the airway, blood pressure, heart rate, and SpO₂ during induction were recorded. Results Induction of anesthesia was satisfactory in group S and in group H. The mean time to loss of the eyelash reflex in group S（63.4±16.2 s） was significantly shorter than that in group I（75.8±22.6 s） and group H （79.7±15.7 s）（P＜0.01）.The mean time to loss of movement to pinpuncture in group I （231.6±77.7 s） was significantly longer than that in group S（189.4±28.7s）and group H （190.5±35.2 s）（P＜0.01）. The incidence of complication during induction in group S and in group H was significantly lower than that in group I. The change of blood pressure was similar in both three groups. Conclusion 5%sevoflurane with 60% N₂O and 2%haothane with 60% N₂O can provide satisfactory rapid inhalation induction. The induction time in group S is shorter than that in group H. The incidence of complication in group I is significantly greater than that in other two groups.
　　Key words：Sevoflurane; Isoflurane; Halothane; Rapid inhalation induction

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　　吸入诱导法常用于小儿麻醉，异氟醚和氟烷是临床常用的麻醉诱导药物。异氟醚对呼吸道有一定的刺激性^[1,2]；氟烷对循环功能有明显抑制作用^[3]。因此，需另找小儿吸入麻醉诱导药物。七氟醚是新型吸入麻醉药，具有血气分配系数低、吸收和恢复较快、具有芳香味等特点，有人推荐可取代异氟醚和氟烷用于小儿吸入诱导麻醉^[4]。本文对58例小儿采用七氟醚、异氟醚或氟烷，在面罩加压深吸气方法下，施行快速吸入诱导麻醉，观察比较三药的诱导平稳程度以及对呼吸道的刺激性，供临床参考。
一、资料与方法
　　选择58例ASAⅠ级、4～11岁、行择期整形外科手术小儿，随机分为三组。七氟醚组（S组,n=20）吸入5%输出浓度七氟醚和60%氧化亚氮（N₂O）；异氟醚组（I组,n=18）吸入3.5%输出浓度异氟醚和60% N₂O；氟烷组（H组,n=20）吸入2%输出浓度氟烷和60% N2O。三种药物的吸入浓度分别为2.0MAC^[5～7]。全部患儿均免用术前药，常规禁饮禁食10 h。术前与患儿充分交谈，讲明吸入诱导的具体方法，以取得小儿配合。采用Drager SA2麻醉机循环回路和Vapor19.3七氟醚、异氟醚和氟烷挥发器，提供七氟醚、异氟醚和氟烷的恒定吸入浓度；调节N₂O-O₂流量为5L/min（3:2）。用Artema mm204-7气体浓度监测仪校正N₂O浓度。体重＜30 kg者使用1 L储气囊；体重＞30 kg者用3 L储气囊。麻醉诱导前将麻醉混合气体先充满麻醉回路约3 min,其间作多次排空储气囊。
　　患儿入室后，常规监测无创血压和 SpO₂。用面罩加压深吸气法吸入麻醉混合气体，待睫毛反射消失后施行辅助通气。针刺测试疼痛反应，消失后建立静脉通路，静注琥珀胆碱1 mg/kg，经口气管插管，连接麻醉呼吸机。吸入安氟醚或七氟醚结合N₂O和静注非去极化肌肉松弛药维持麻醉。全部操作由同一医生实施，并由固定助手每10 s测试一次睫毛反射，睫毛反射消失后，每10s针刺一次足心，记录睫毛反射和疼痛反应消失的时间。并观察记录麻醉诱导期的躲闪、咳嗽、呕吐、喉痉挛、分泌物增加以及躯体动作等反应，同时记录吸入诱导前、睫毛反射消失时以及疼痛反应消失时的收缩压、舒张压、平均动脉压、心率及SpO₂。采用方差分析、卡方检验及t检验统计处理,P＜0.05认为有显著性差异。
二、结　果
　　三组小儿的年龄、体重和性别比均无统计学差异。吸入诱导时均无呕吐。诱导期躲闪、咳嗽、喉痉挛、分泌物增加、以及躯体扭动情况以I组明显（见表1）。睫毛反射消失时间以S组最短；针刺疼痛反应消失时间以I组最长（见表2）。三组小儿吸入诱导期的血压均有一定程度下降，以氟烷诱导时最为明显（表3）。异氟醚诱导在发生喉痉挛时伴有HR明显增快和SpO₂一过性下降，有3例SpO₂最低达90%。三组均未发生需要紧急处理的严重并发症（如严重心动过缓，支气管痉挛等）。
三、讨　论
　　采用面罩加压深吸气法吸入相同 MAC的七氟醚、异氟醚或氟烷时，以七氟醚和氟烷的诱导效果较为满意，其中七氟醚的诱导速度最快。小儿对七氟醚和氟烷的接受程度较好。氟烷组小儿只有一例在扣面罩后出现躲闪反应，而异氟醚组18例小儿中有7例在扣面罩后出现躲闪反应，一例用手推开面罩拒绝吸入。部分小儿在吸入诱导时伴有兴奋现象，其程度和发生率与药物种类和诱导时间有关。笔者认为异氟醚蒸气的刺激性较强，吸入之初小儿合作程度相对较差，诱导时间相应延长，兴奋期也较明显。七氟醚或氟烷在吸入诱导时也均出现不同程度的骚动。
  吸入麻醉药对呼吸道的刺激性是影响诱导平稳程度的主要原因之一。早年对异氟醚的呼吸道刺激性报道不一^[1,8]，多数认为有一定的刺激性^[1,2,9]，刺激较重时可出现SpO₂ 明显下降,甚至发生低氧血症^[2,9]。建议在临床应用时采用逐步增加异氟醚浓度吸入^[8]、湿化吸入气体以及同时吸入二氧化碳等方法，以求减轻刺激^[10-11]。本文也证实加压深吸高浓度异氟醚诱导时，对小儿呼吸道的刺激性较明显，部分小儿出现咳嗽、分泌物异常增加以及喉痉挛等反应，伴有SpO₂一过性下降，最低达90%。提示不宜采用高浓度异氟醚快速吸入诱导麻醉。
　　氟烷快速吸入诱导的主要顾虑在其对心血管的抑制作用。Agnor等^[12]报道应用5%氟烷快速吸入诱导时,心律失常发生率明显高于七氟醚。Yurino等^[13]也报道类同结果。本文也证实2%氟烷快速吸入对小儿的血压、心率的抑制作用较七氟醚和异氟醚相对明显，但尚无临床意义。

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四、结　论
　　小儿采用5%七氟醚或2%氟烷加60% N₂O快速吸入诱导均属安全可行，以七氟醚的诱导速度最快；异氟醚则不适宜用于快速吸入诱导。

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