右美托咪定对小儿吸入七氟烷最低肺泡有效浓度的影响

目的：探讨右美托咪定（dexmedetomidine，Dex）对小儿吸入七氟烷最低肺泡有效浓度（MAC）的影响。方法：择期全麻患儿31例，年龄2～8岁，美国麻醉医师协会（ASA）分级为1～1I级，随机分为对照组（七氟烷加0．9％氯化钠液，n=17）和研究组（七氟烷加Dex，n=14）。所有患儿入室后均吸入8％七氟烷行麻醉诱导，开放静脉通路，研究组给药方式为负荷量0．5〉g／kg，后以0．5μg／（kg·h）维持。对照组组予等量0．9％氯化钠液。完成气管插管后，连接气体分析仪，并将七氟烷调至预定浓度。采用序贯法进行研究，七氟烷初始呼气末浓度差值均为2．0vol%，相邻浓度差值为0．2vol％，七氟烷呼气末浓度达到预定值并维持15min后行手术切皮。测定2组七氟烷的最低肺泡有效浓度（MAC），记录诱导前、切皮前及切皮后的心率及平均动脉压变化。结果：对照组和研究组惠儿吸入七氟烷的MAC分别为2．46％（95％可信区间为2．32％～2．60％）和1．90％（95%可信区间为1．78％～2．02％），与对照组相比，研究组MAC降低了23％（P〈0．05）。所有患儿均无心动过缓、低血压等不良反应。结论：右美托咪定可降低小儿吸入七氟烷的MAC，且不良反应少。

Effects of Dexmedetomidine on Minimum Alveolar Concentration of Inhaling Sevoflurane in Children

Objective： To explore the effection of dexmedetomidine（Dex） on the minimum alveolar concentration（MAC） of sevoflurane（Sev） in children. Methods： We conducted a randomized trail. A total of 31 children, aged 2-8 years, undergoing general anesthesia were randomly divided into two groups either the control group（Sev ＋ 0.9% NaCL, n = 17） or the study group（Sev ＋ Dex, n = 14）. All of the children were induced by inhaling 8% Sev. Then the venous access were obtained. In study group, the loading dose of Dex was 0.5 vg/kg injected in 10 rain and then maintained in 0.5 vg/kg/h. Children in control group were injected equivalent volume of normal saline. After intubation, we connected the gas analyzer to the endotraeheal tube and adjust the objective concentration of Sev. The MAC was determined using the technique as described by Dixon method. The initial end-tidal concentration of Sev was 2.0 vol%, difference between adjacent with 0.2 vol%. End-tidal concentration reached the predetermined value and maintained 15 min before surgical incision. Next we measured the MAC of Sev and observed the incidence of operative adverse reaction. Results： The MAC in control group and study group were 2.46 % （95 %confidence interval 2.32%-2.60 % ）and 1.90 % （95 % confidence interval 1.78 %-2.02 % ）respectively. The MAC of study group were significantly lower by 23% than that of control group. We did not find any adverse reaction such as bradycardia and hypotension during the operation. Conclusions： Dex can reduce the MAC of Sev, and there is no adverse effection in children.