右美托咪啶抑制患者清醒纤维支气管镜插管反应的临床剂量探讨

【摘要】 目的 测定右美托咪啶抑制患者清醒纤维支气管镜插管反应的半数有效剂量(ED50)。方法 选择全身麻醉、预计存在困难气道的20例患者,ASA分级Ⅰ或Ⅱ级,年龄38~65岁,体重45~70 kg;右美托咪啶持续静脉输注10 min后,用1%丁卡因对舌根部、咽喉部及声门上进行表面麻醉,2%利多卡因2 mL经环甲膜穿刺行气管表面麻醉,然后行经鼻纤维支气管镜插管。右美托咪啶的给药剂量按序贯法确定,相邻剂量之间的比率为1.2。采用改良Dixon序贯法计算右美托咪啶抑制清醒纤维支气管镜插管反应的ED50及其95%可信区间,并采用logistic回归模型进行概率单位转换分析ED50及其95%可信区间。结果 右美托咪啶抑制患者清醒纤维支气管镜插管反应的ED50为0.74 μg/kg,其95%可信区间为0.68 μg/kg~0.82 μg/kg。结论 静脉输注右美托咪啶0.74 μg/kg,可以为50%的已行气道表面麻醉的患者在清醒纤维支气管镜插管过程中提供满意的气管插管条件,且无气管插管反应发生。

Discussion of clinical dose of dexmedetomidine for inhibiting reaction of awake fiberoptic bronchoscopic intubation

Objective To investigate the effective dose of dexmedetomidine at which awake fiberoptic bronchoscopic intubation was tolerable in 50% of patients（ED 50）.Methods Twenty patients with difficult airways,.ASA physical grading Ⅰ or Ⅱ,.aged 38-65 years,.body weight 45-70 kg,undergoing elective surgery under general anaethesia were enrolled in this study..After intravenous administration of dexmedetomidine over 10 minutes,the local mucous anesthesia of tongue-root,throat and supraglottic region was performed with 1% dicaine by laryngeal spray,.and the intratracheal topical anesthesia was performed with 2 ml of 2% lidocaine through thyrocricocentesis..Median effective dose（ED 50） was determined by modified Dixon＇s up-and-down sequential experiment.The ratio of two successive dose of dexmedetomidine was 1.2..The ED 50 and 95% confidence interval.（CI）.of dexmedetomidine were calculated by the modified Dixon＇s up-and-down method and the ED 50 and 95% CI were analyzed using the probit test in a logistic regression model..Results ED 50 of dexmedetomidine for awake fiberoptic bronchoscopic intubation obtained by modified Dixon＇s up-and-down method was 0.74 μg /kg（95%CI 0.68-0.82 μg /kg）.Conclusion Intravenous administration of dexmedetomidine 0.74 μg /kg over 10 min in conjunction with local anesthesia would provide good intubating condition for awake fiberoptic bronchoscopic intubation in 50% of patients,and there are no intubation responses.