不同剂量的右美托咪定术前经鼻雾化给药对小儿喉罩置入时七氟醚EC_(50)的影响

Effects of Two Intranasal Dexmedetomidine Doses as Premedication on Sevoflurane EC_(50) for Successful Laryngeal Mask Airway Placement in Children

目的观察术前经鼻雾化给予不同剂量的右美托咪定对小儿喉罩置入时七氟醚EC50的影响。方法将41例年龄3-6岁,美国麻醉医师协会Ⅰ级,择期全麻下行整形手术的患儿按照随机数字表法随机分为2组：右美托咪定1μg/kg组（D1组,n=21）、右美托咪定2μg/kg组（D2组,n=20）。进入手术室前30 min所有患儿经鼻雾化喷入观察药物。进入手术室后所有患儿经面罩行七氟醚吸入诱导,七氟醚浓度为8%,氧气流量为6 L/min。患儿瞳孔固定中位后七氟醚浓度降为5%,氧气流量为3 L/min。静脉置管成功后根据Dixon’s序贯法调整患儿喉罩置入时呼气末七氟醚浓度,维持10 min后置入喉罩,序贯法实施的初始浓度为2%,相邻浓度比值为1∶1.2,根据上一例患儿喉罩置入的情况调整下一例患儿呼气末七氟醚浓度。观察患儿入室时的脑电双频指数、对吸入诱导时面罩的接受程度、置入喉罩时的反应情况,记录喉罩置入时呼气末七氟醚气体浓度。结果患儿入手术室时的脑电双频指数值D2组为77.4±3.6,显著低于D1组的87.4±1.9（P〈0.05）;患儿对面罩的接受程度D1组为76.2%,D2组为90.0%,两组差异无统计学意义;喉罩置入时七氟醚EC50D1组为1.59%（95%CI=1.41%-1.78%）,D2组为1.09%（95%CI=0.89%-1.28%）,D2组显著低于D1组（P〈0.05）。结论较右美托咪定1μg/kg相比,麻醉前30 min经鼻雾化喷入右美托咪定2μg/kg,可显著降低喉罩置入时七氟醚的EC50。

Objective To observe the effects of two different intranasal dexmedetomidine doses as premedication on the EC50 of sevoflurane for successful laryngeal mask airway placement in children. Methods Children aged 3-6 years,of American Society of Anesthesiologists physical status Ⅰ,and scheduled for plastic surgery were enrolled in this study. Children were assigned to receive either spray administration of intranasal dexmedetomidine 1 μg / kg（ group D1,n = 21） or 2 μg / kg（ group D2,n = 20） approximately 30 minutes before anesthesia. Anesthesia was induced with sevoflurane up to 8 % in 100 % O2,with fresh gas flow set to 6 L / min. After the pupil fixed to the middle position,sevoflurane dial setting was reduced to 5 % andfresh gas flow reduced to 3 L / min. The endtidal sevofluran（ ETsevo） concentration for laryngeal mask airway insertion sustained for 10 minutes after vein intubation,which was determined according to the Dixon＇s up and down method. The initial endtidal sevoflurane concentration in each group was set at 2 %. ETsevowas increased /decreased（ 1 ∶1. 2） in the next patient according to the response to laryngeal mask airway insertion. Bispectral index,mask acceptance,all response to laryngeal mask airway insertion,and ETsevoof laryngeal mask airway insertion of children were recorded. Results The bispectral index value was 77. 4 ± 3. 6 in group D2,which was significantly lower than that（ 87. 4 ± 1. 9） in group D1 when children entered operation room（ P〈0.05）. Mask acceptance was 76. 2 % in group D1 and 90. 0 % in group D2. The EC50 of sevoflurane for laryngeal mask airway insertion was 1. 09 %（ 95 % CI = 0. 89 %- 1. 28 %） in group D2,which was lower than1. 59 %（ 95 % CI = 1. 41 %- 1. 78 %） in group D1（ P 0. 05）. Conclusion Compared with the dose of1 μg / kg,spray administration of intranasal dexmedetomidine 2 μg / kg as premedication can reduce the sevoflurane EC50 for successful laryngeal mask airway placement in children.