硬膜外注射利多卡因抑制患者带状疱疹性疼痛的半数有效浓度

Median effective concentration of epidural lidocaine inhibiting herpetic neuralgia

目的 确定硬膜外注射利多卡因抑制患者带状疱疹性疼痛的半数有效浓度（EC50）.方法 胸腰段带状疱疹性疼痛患者,性别不限,20 ～ 60岁,体重指数18 ～ 25 kg/m2,ASA分级Ⅰ或Ⅱ级.数字减影血管造影机引导下行硬膜外穿刺置管术,注射含有碘佛醇＋利多卡因的混合液,利多卡因初始浓度为0.37％,采用序贯法进行试验,镇痛有效时下一例患者下调一级浓度,否则上调一级浓度,相邻浓度之比为1.06.镇痛有效的标准：注药后30 min内VAS评分≤1分.采用Dixon公式计算EC50及其95％可信区间.结果 硬膜外注射利多卡因抑制患者带状疱疹性疼痛的EC50为0.199％,其95％可信区间为0.168％～ 0.216％.结论 硬膜外注射利多卡因抑制患者带状疱疹性疼痛的EC50为0.199％.

Objective To determine the median effective concentration （EC50） of epidural lidocaine inhibiting herpetic neuralgia.Methods The patients with thoracic or lumbar herpetic neuralgia,aged 20-60 yr,with body mass index of 18-25 kg/m2,of ASA physical status Ⅰ or Ⅱ,were included in the study.Epidural catheter was placed under the guidance of the digital subtraction angiography （DSA）.An injection of iohexol mixed with lidocaine was given under the guidance of DSA to make sure that drug solution covered all the injured nerve roots.The initial concentration of lidocaine was 0.37％.The concentration was determined by up-and-down sequential allocation.Each time the concentration of lidocaine increased/decreased in the next patient depending on whether or not the analgesia was effective.The ratio between the two successive concentrations was 1.06.Effective analgesia was defined as VAS score ≤ 1 within 30 min after administration.The EC50 and 95 ％ confidence interval of lidocaine inhibiting herpetic neuralgia were calculated using Dixon formula.Results The EC50 of lidocaine inhibiting herpetic neuralgia was 0.199 ％ and the 95 ％ confidence interval was 0.168 ％-0.216 ％.Conclusion The EC50 of epidural lidocaine required to inhibit herpetic neuralgia is 0.199％.