Nishina K, Mikawa K, Maekawa N, Obara H
Department of Anesthesiology, Kobe University School of Medicine, Japan.
Anesthesiology. 1995 May;82(5):1126-30. doi: 10.1097/00000542-199505000-00006.
Clonidine, which is known to have analgesic and sedative properties, has recently been shown to be an effective preanesthetic medication in children. The drug may cause side effects, including bradycardia and hypotension. This study was conducted to evaluate the ability of intravenous atropine to increase the heart rate (HR) in awake children receiving clonidine preanesthetic medication.
We studied 96 otherwise healthy children, 8-13 yr old, undergoing minor surgery. They received, at random, oral clonidine 2 or 4 micrograms.kg-1 or placebo 105 min before scheduled induction of anesthesia. Part I (n = 48, 16 per group): When hemodynamic parameters after insertion of a venous catheter had been confirmed to be stable, atropine was administered in incremental doses of 2.5, 2.5, and 5 micrograms.kg-1 every 2 min. The HR and blood pressure were recorded at 1-min intervals. Part II (n = 48, 16 per group): After the recording of baseline hemodynamic values, successive doses of atropine (5 micrograms.kg-1 every 2 min, to 40 micrograms.kg-1), were administered until HR increased by 20 beats.min-1. The HR and blood pressure were recorded at 1-min intervals.
Part I: The increases in HR in response to a cumulative dose of atropine 10 micrograms.kg-1 were 33 +/- 3%, 16 +/- 3%, and 8 +/- 2% (mean +/- SEM) in children receiving placebo, clonidine 2 micrograms.kg-1, and clonidine 4 micrograms.kg-1, respectively (P < 0.05). Part II: The HR in the control group increased by more than 20 beats.min-1 in response to atropine 20 micrograms.kg-1 or less. In two patients in the clonidine 4 micrograms.kg-1 group, HR did not increase by 20 beats.min-1 even after 40 micrograms.kg-1 of atropine.
Oral clonidine premedication (4 micrograms.kg-1) blunted the increase in HR after intravenous atropine in awake children, although clonidine 2 micrograms.kg-1 did not. A larger dose of atropine was required to increase the HR by 20 beats.min-1 in children receiving the premedicant in the larger dose.
可乐定具有镇痛和镇静作用，最近已被证明是一种有效的儿童麻醉前用药。该药物可能会引起副作用，包括心动过缓和低血压。本研究旨在评估静脉注射阿托品对接受可乐定麻醉前用药的清醒儿童心率（HR）的提升能力。
我们研究了96名8至13岁、行小手术的健康儿童。在预定麻醉诱导前105分钟，他们被随机给予口服可乐定2或4微克·千克⁻¹或安慰剂。第一部分（n = 48，每组16人）：在确认静脉导管插入后的血流动力学参数稳定后，每隔2分钟以2.5、2.5和5微克·千克⁻¹的递增剂量给予阿托品。每隔1分钟记录心率和血压。第二部分（n = 48，每组16人）：在记录基线血流动力学值后，连续给予阿托品（每隔2分钟5微克·千克⁻¹，直至40微克·千克⁻¹），直至心率增加20次·分钟⁻¹。每隔1分钟记录心率和血压。
第一部分：接受安慰剂、2微克·千克⁻¹可乐定和4微克·千克⁻¹可乐定的儿童，对累积剂量10微克·千克⁻¹阿托品的心率增加分别为33±3%、16±3%和8±2%（平均值±标准误）（P<0.05）。第二部分：对照组中，对20微克·千克⁻¹或更低剂量的阿托品，心率增加超过20次·分钟⁻¹。在4微克·千克⁻¹可乐定组的两名患者中，即使给予40微克·千克⁻¹阿托品后，心率也未增加达20次·分钟⁻¹。
口服可乐定预处理（4微克·千克⁻¹）会减弱清醒儿童静脉注射阿托品后的心率增加，尽管2微克·千克⁻¹可乐定不会。对于接受较大剂量预处理药物的儿童，需要更大剂量的阿托品才能使心率增加20次·分钟⁻¹。
