Kimura T, Tanaka M, Nishikawa T
Department of Anesthesia, Iwaki Kyoritsu General Hospital, Japan.
Anesthesiology. 1998 Jun;88(6):1507-10. doi: 10.1097/00000542-199806000-00014.
Clonidine reduces heart rate (HR) responses to atropine, whereas neostigmine causes bradycardia. This study was designed to determine whether clonidine premedication would reduce tachycardia after neostigmine-atropine administration.
Fifty adult patients without cardiovascular disorders who were scheduled for elective surgeries were randomly assigned to receive approximately 5 microg/kg (oral clonidine clonidine group, n=25) or no clonidine (control group, n=25) 90 min before induction of general anesthesia. After tracheal intubation, anesthesia was maintained with N2O and 12% isoflurane in oxygen while patients were paralyzed with vecuronium and mechanically ventilated. When surgeries were completed, adequate spontaneous respiration, responses to verbal commands, and sustained tetanus by stimulating the ulnar nerve were confirmed, and patients' tracheas were extubated. Then a mixture of 0.05 mg/kg neostigmine and 0.02 mg/kg atropine was administered intravenously over 20 s under stable hemodynamic condition (systolic blood pressure and HR within +/-5% of preceding values), and blood pressure and HR were measured noninvasively at 1-min intervals for 10 min.
Increases in HR in the clonidine group were significantly less 1-4 min after neostigmine--atropine injections compared with HR values in the control group. A maximum increase in HR of the clonidine group was also significantly less than the control group (15+/-7 vs. 23+/-10 beats/min; means+/-SD), whereas absolute values of mean blood pressure were similar. Severe bradycardia (HR < 50 beats/min) developed in no patients in either group.
Premedication with 5 microg/kg oral clonidine attenuates the initial increases in HR without subsequent decreases in HR.
可乐定可降低心率（HR）对阿托品的反应，而新斯的明会导致心动过缓。本研究旨在确定可乐定预处理是否会降低新斯的明 - 阿托品给药后的心动过速。
50例计划接受择期手术且无心血管疾病的成年患者，在全身麻醉诱导前90分钟随机分为两组，一组接受约5μg/kg口服可乐定（可乐定组，n = 25），另一组不接受可乐定（对照组，n = 25）。气管插管后，用N₂O和12%异氟醚维持麻醉，同时患者用维库溴铵使其肌肉松弛并进行机械通气。手术结束后，确认患者有足够的自主呼吸、对言语指令有反应以及刺激尺神经时能维持强直收缩，然后拔除气管导管。随后在血流动力学稳定的情况下（收缩压和心率在前值的±5%范围内），在20秒内静脉注射0.05mg/kg新斯的明和0.02mg/kg阿托品的混合物，并在10分钟内每隔1分钟无创测量血压和心率。
与对照组相比，可乐定组在新斯的明 - 阿托品注射后1 - 4分钟心率增加明显较少。可乐定组心率的最大增加值也明显低于对照组（15±7对23±10次/分钟；均值±标准差），而平均血压的绝对值相似。两组均无患者出现严重心动过缓（心率 < 50次/分钟）。
5μg/kg口服可乐定预处理可减轻心率的初始增加，且随后心率不会降低。
