Gottrup H, Bach F W, Arendt-Nielsen L, Jensen T S
Department of Neurology, University Hospital of Aarhus, Aarhus and Danish Pain Research Center, Aarhus University, Denmark.
Br J Anaesth. 2000 Oct;85(4):520-8. doi: 10.1093/bja/85.4.520.
We examined the effect of the subcutaneous infiltration of ketamine, lidocaine and saline before injury on capsaicin-induced pain and hyperalgesia. Twelve healthy volunteers participated in two separate, randomized, double-blind, placebo-controlled crossover experiments. In experiment 1, 100 micrograms capsaicin was injected intradermally in one volar forearm 10 min after the skin had been pretreated with lidocaine 20.0 mg in 2.0 ml or 0.9% saline 2.0 ml at the capsaicin injection site. In experiment 2, a similar capsaicin test was given 10 min after the skin had been pretreated with ketamine 5 mg in 2.0 ml or 0.9% saline 2.0 ml. To control for possible systemic effects, the capsaicin injection site was pretreated by injection of saline into the skin and the contralateral arm was treated with active drug, and vice versa. Outcome measures were spontaneous pain, pain evoked by punctate and brush stimuli, and areas of brush-evoked and punctate-evoked hyperalgesia. Lidocaine reduced all measures compared with placebo (P < 0.001), whereas ketamine failed to change any measures. Pain scores and areas of hyperalgesia were not affected when the contralateral site was infiltrated with ketamine or lidocaine. Lidocaine produced no side-effects, whereas ketamine produced paraesthesia, dizziness and sleepiness in six out of 24 (25%) cases. Blocking peripheral sodium channels with locally administered lidocaine reduces spontaneous pain and capsaicin-induced hyperalgesia but local block with the NMDA-type glutamate receptor antagonist ketamine has no effect on capsaicin-induced pain and hyperalgesia.
我们研究了损伤前皮下注射氯胺酮、利多卡因和生理盐水对辣椒素诱发的疼痛和痛觉过敏的影响。12名健康志愿者参与了两项独立的、随机的、双盲的、安慰剂对照的交叉实验。在实验1中，在辣椒素注射部位用2.0 ml含20.0 mg利多卡因或2.0 ml 0.9%生理盐水预处理皮肤10分钟后，将100微克辣椒素皮内注射到一侧掌侧前臂。在实验2中，在皮肤用2.0 ml含5 mg氯胺酮或2.0 ml 0.9%生理盐水预处理10分钟后，进行类似的辣椒素测试。为控制可能的全身效应，通过向皮肤注射生理盐水对辣椒素注射部位进行预处理，对侧手臂用活性药物治疗，反之亦然。观察指标为自发痛、点状和刷擦刺激诱发的疼痛以及刷擦诱发和点状诱发痛觉过敏的区域。与安慰剂相比，利多卡因降低了所有指标（P < 0.001），而氯胺酮未能改变任何指标。当对侧部位注射氯胺酮或利多卡因时，疼痛评分和痛觉过敏区域未受影响。利多卡因未产生副作用，而氯胺酮在24例中有6例（25%）产生了感觉异常、头晕和嗜睡。局部应用利多卡因阻断外周钠通道可减轻自发痛和辣椒素诱发的痛觉过敏，但局部应用NMDA型谷氨酸受体拮抗剂氯胺酮对辣椒素诱发的疼痛和痛觉过敏无影响。
