De Kock M, Martin N, Scholtes J L
Department of Anesthesiology, University of Louvain, St Luc Hospital, Brussels, Belgium.
Anesthesiology. 1992 Sep;77(3):457-62. doi: 10.1097/00000542-199209000-00009.
Epidural clonidine produces regional anesthesia as well as sedation and a decrease in anesthetic requirements. To assess these effects, the electroencephalogram (EEG) was recorded after epidural or intravenous (iv) injection of clonidine during enflurane/N2O anesthesia. Eighteen ASA physical status 1 women undergoing vaginal hysterectomy were allocated randomly to receive epidural clonidine (8 micrograms.kg-1 in 4 ml over 2 min) and iv saline (10 ml over 14 min); or epidural saline (4 ml over 2 min) and iv clonidine (8 micrograms.kg-1 in 10 ml over 14 min); or epidural saline (4 ml over 2 min) and iv saline (10 ml over 14 min). The level of anesthesia was kept constant beginning 10 min before and until 44 min after epidural injection. EEG power spectral analysis was performed throughout the study period using a 2-min average of 8-9-s epochs. Clonidine significantly reduced EEG total power only after epidural administration (P less than 0.05). Relative power increased in the delta band in both the epidural and iv clonidine groups (P less than 0.001). The depression of the total EEG power after epidural injection could be explained neither by systemic absorption alone nor by hemodynamic variations. It may represent the contribution of the direct spinal action of this alpha 2-adrenergic agonist to general anesthesia.
硬膜外注射可乐定可产生局部麻醉以及镇静作用，并降低麻醉需求。为评估这些效应，在安氟醚/N₂O麻醉期间，硬膜外或静脉注射可乐定后记录脑电图（EEG）。18例拟行阴道子宫切除术的美国麻醉医师协会（ASA）身体状况1级女性被随机分配，分别接受硬膜外注射可乐定（8微克·千克⁻¹，溶于4毫升，2分钟内注射完毕）和静脉注射生理盐水（10毫升，14分钟内注射完毕）；或硬膜外注射生理盐水（4毫升，2分钟内注射完毕）和静脉注射可乐定（8微克·千克⁻¹，溶于10毫升，14分钟内注射完毕）；或硬膜外注射生理盐水（4毫升，2分钟内注射完毕）和静脉注射生理盐水（10毫升，14分钟内注射完毕）。从硬膜外注射前10分钟开始直至注射后44分钟，麻醉水平保持恒定。在整个研究期间，使用8 - 9秒时间段的2分钟平均值进行EEG功率谱分析。仅在硬膜外给药后，可乐定显著降低了EEG总功率（P < 0.05）。硬膜外和静脉注射可乐定组的δ波频段相对功率均增加（P < 0.001）。硬膜外注射后EEG总功率的降低既不能仅由全身吸收来解释，也不能由血流动力学变化来解释。它可能代表了这种α₂肾上腺素能激动剂的直接脊髓作用对全身麻醉的贡献。
