Doak G J, Duke P C
Department of Anaesthesia, University of Manitoba, Winnipeg.
Can J Anaesth. 1993 Jul;40(7):612-8. doi: 10.1007/BF03009697.
Induction of anaesthesia is often associated with undesirable variations in blood pressure and heart rate. Clonidine has been demonstrated to attenuate many of these undesirable effects when used as a premedicant. Other alpha 2 adrenergic agonists have been used to ameliorate the cardiostimulatory effects of ketamine in animals but there are few data on the use of this combination in humans. The effect of oral clonidine premedication, 5 micrograms.kg-1 on the haemodynamic changes induced by i.v. ketamine was studied in 42 patients volunteers. Ninety minutes before surgery, patients randomly received clonidine (C), diazepam (D), or a placebo (P) in a double-blinded fashion. Anaesthesia was induced with a ketamine infusion of 1 mg.kg-1 x min-1 until loss of consciousness. Heart rate and phasic blood pressure were measured noninvasively prior to induction, before and up to seven minutes after tracheal intubation. There were no differences in demographics or baseline vital signs among the three groups. With ketamine administration, increases in heart rate and blood pressure were less in those patients given C preoperatively than in those who received either D or P. The peak increase in mean blood pressure was 39% (C) versus 70% (D) and 55% (P) (P < 0.01). Heart rate increased by a maximum of 20% (C) versus 41% (D) and 46% (P) (P < 0.01). We conclude that oral clonidine attenuates the hyperdynamic effects of anaesthetic induction with i.v. ketamine.
麻醉诱导常常伴随着血压和心率的不良波动。已证明可乐定作为术前用药时可减轻许多此类不良影响。其他α2肾上腺素能激动剂已被用于改善动物体内氯胺酮的心脏刺激作用，但关于这种联合用药在人体中的应用数据很少。本研究在42例患者志愿者中探讨了口服5微克·千克-1可乐定术前用药对静脉注射氯胺酮所致血流动力学变化的影响。手术前90分钟，患者以双盲方式随机接受可乐定（C）、地西泮（D）或安慰剂（P）。以1毫克·千克-1×分钟-1的速率静脉输注氯胺酮诱导麻醉直至意识消失。在诱导前、气管插管前及插管后长达7分钟无创测量心率和相位血压。三组患者的人口统计学特征和基线生命体征无差异。给予氯胺酮后，术前接受C组患者的心率和血压升高幅度低于接受D组或P组患者。平均血压峰值升高幅度为39%（C组），而D组为70%，P组为55%（P<0.01）。心率最大升高幅度为20%（C组），而D组为41%，P组为46%（P<0.01）。我们得出结论，口服可乐定可减轻静脉注射氯胺酮麻醉诱导的高动力效应。
