De Kock M, Crochet B, Morimont C, Scholtes J L
Department of Anesthesiology, University of Louvain, St. Luc Hospital, Brussels, Belgium.
Anesthesiology. 1993 Sep;79(3):525-31. doi: 10.1097/00000542-199309000-00016.
Intravenous and epidural clonidine both produce postoperative analgesia. Several experimental reports demonstrate a spinal site of action for the analgesic effects of this alpha 2-adrenoceptor agonist. Therefore, the authors evaluated the clinical analgesic benefits of using clonidine, both intra- and postoperatively, by the epidural or the intravenous route.
Using a randomized prospective double-blind study design, 40 patients, between 18 and 50 yr of age, undergoing intestinal surgery under general propofol/nitrous oxide anesthesia, were enrolled. Before anesthesia, an epidural catheter was inserted at the L1-L2 interspace. At induction, a clonidine infusion was started at the doses of 4 micrograms/kg in 10 ml during 20 min, followed by 2 micrograms.kg-1 x h-1 (5 ml/h) during 12 h, either by the epidural (group 1) or by the intravenous (group 2) route. Intraoperatively, increased blood pressure and heart rate not responding to additional propofol bolus (0.5 mg/kg) was treated with a bolus of alfentanil (7 micrograms/kg). Postoperatively, morphine boluses (1.5 mg) were given through a PCA device according to the patient's need. Intraoperative analgesia was assessed by the alfentanil requirements. Postoperative analgesia was assessed by recording the morphine requirements, the visual analogue scale (VAS) at rest and after mobilization, and the patients' analgesia scale at 0, 3, 6, 12, 18, 24, and 36 postoperative hours. Sedation analogue scale and side effects were also recorded. Heart rate and blood pressure were particularly detailed during the first 2 h of the clonidine infusion. Plasma clonidine concentrations were measured after 20 min and 6, 12, and 24 h.
Epidural clonidine significantly reduced the intraoperative alfentanil requirements (0.93 +/- 1.2 in group 1 vs. 2.4 +/- 1.8 mg in group 2). The postoperative morphine requirements were also reduced during the first 6 h (8.3 +/- 5.8 in group 1 vs. 17.8 +/- 13.4 mg in group 2). The VAS were comparable in both groups, despite the better patients' analgesia score reported in the epidural group during the first 12 h. There was no difference in sedation score at any time interval considered. Epidural and intravenous clonidine reduced heart rate and blood pressure to the same extent. The plasma clonidine concentrations were less in the epidural group only after the loading doses.
Epidural clonidine reduces the intra- and early postoperative analgesic requirements when compared with the same dose given by the intravenous route. The side effects were similar with the two routes of administration.
静脉注射和硬膜外注射可乐定均可产生术后镇痛效果。多项实验报告表明，这种α2肾上腺素能受体激动剂的镇痛作用部位在脊髓。因此，作者评估了通过硬膜外或静脉途径在手术中和术后使用可乐定的临床镇痛益处。
采用随机前瞻性双盲研究设计，纳入40例年龄在18至50岁之间、在丙泊酚/氧化亚氮全身麻醉下接受肠道手术的患者。麻醉前，在L1-L2间隙插入硬膜外导管。诱导时，开始以4微克/千克的剂量在20分钟内静脉输注10毫升可乐定，随后在12小时内以2微克·千克-1·小时-1（5毫升/小时）的速度持续输注，通过硬膜外途径（第1组）或静脉途径（第2组）给药。术中，对额外给予丙泊酚推注（0.5毫克/千克）后血压和心率仍升高的情况，给予阿芬太尼推注（7微克/千克）进行处理。术后，根据患者需要通过PCA装置给予吗啡推注（1.5毫克）。术中镇痛通过阿芬太尼需求量进行评估。术后镇痛通过记录吗啡需求量、静息和活动后的视觉模拟评分（VAS）以及术后0、3、6、12、18、24和36小时的患者镇痛评分进行评估。还记录了镇静模拟评分和副作用。在可乐定输注的前2小时，特别详细记录心率和血压。在20分钟以及6、12和24小时后测量血浆可乐定浓度。
硬膜外注射可乐定显著降低了术中阿芬太尼需求量（第1组为0.93±1.2毫克，第2组为2.4±1.8毫克）。术后前6小时吗啡需求量也有所降低（第1组为8.3±5.8毫克，第2组为17.8±13.4毫克）。尽管硬膜外组在前12小时报告的患者镇痛评分更好，但两组的VAS相当。在任何考虑的时间间隔内，镇静评分均无差异。硬膜外和静脉注射可乐定对心率和血压的降低程度相同。仅在负荷剂量后，硬膜外组的血浆可乐定浓度较低。
与静脉途径给予相同剂量相比，硬膜外注射可乐定可降低术中和术后早期的镇痛需求。两种给药途径的副作用相似。
