Fehr S B, Zalunardo M P, Seifert B, Rentsch K M, Rohling R G, Pasch T, Spahn D R
Institute of Anaesthesiology, University Hospital Zurich, Switzerland.
Br J Anaesth. 2001 May;86(5):627-32. doi: 10.1093/bja/86.5.627.
Assessment of the effect of clonidine on depth of anaesthesia is difficult because clonidine combines analgesic, sedative and direct haemodynamic effects. We thus evaluated the influence of clonidine on the bispectral index (BIS) and its potential dose-sparing effect on propofol. After induction of anaesthesia with target-controlled infusion of propofol and obtaining an unchanged bispectral index (pre-BIS), clonidine 4 microg kg(-1) or placebo was administered randomly to 50 patients in a double-blind manner. Subsequently, if there was a decrease in BIS we reduced the target concentration of propofol until pre-BIS was reached. The pre-BIS was maintained and a remifentanil infusion was added during surgery. The courses of the BIS, heart rate and blood pressure were recorded and the total amounts of intra-operative propofol and remifentanil were determined. Assessment of implicit memory during anaesthesia was performed with an auditory implicit memory test consisting of item sequences. Administration of clonidine resulted in a decrease in the BIS from 45 (SD 4) to 40 (6) (P<0.001), which allowed a reduction of propofol target concentration from 3.3 (0.6) to 2.7 (0.7) microg ml(-1) (P<0.001) and measured propofol concentration from 2.9 (0.6) to 2.5 (0.7) kg ml(-1) (P=0.009) in order to maintain the pre-BIS value. During subsequent surgery, propofol requirements were reduced by 20% (P=0.002) in the clonidine group and a similar amount of remifentanil was used in each group. The increase in anaesthetic depth given by clonidine can therefore be measured with bispectral EEG analysis and allows reduction of the propofol dose to achieve a specific depth of anaesthesia.
评估可乐定对麻醉深度的影响很困难，因为可乐定兼具镇痛、镇静及直接的血流动力学效应。因此，我们评估了可乐定对脑电双频指数（BIS）的影响及其对丙泊酚的潜在剂量节省效应。在以靶控输注丙泊酚诱导麻醉并获得稳定的脑电双频指数（预BIS）后，将4μg/kg的可乐定或安慰剂以双盲方式随机给予50例患者。随后，如果BIS降低，我们就降低丙泊酚的靶浓度，直至达到预BIS。维持预BIS，并在手术期间加用瑞芬太尼输注。记录BIS、心率和血压的变化过程，并测定术中丙泊酚和瑞芬太尼的总量。采用由项目序列组成的听觉内隐记忆测试对麻醉期间的内隐记忆进行评估。给予可乐定后，BIS从45（标准差4）降至40（6）（P<0.001），这使得丙泊酚靶浓度从3.3（0.6）降至2.7（0.7）μg/ml（P<0.001），实测丙泊酚浓度从2.9（0.6）降至2.5（0.7）μg/ml（P=0.009），以维持预BIS值。在随后的手术中，可乐定组的丙泊酚需求量减少了20%（P=0.002），且两组使用的瑞芬太尼量相似。因此，可乐定引起的麻醉深度增加可以用脑电双频指数脑电图分析来测量，并可减少丙泊酚剂量以达到特定的麻醉深度。
