Clonidine, a prototype alpha2-adrenoreceptor agonist, has been shown to be effective as a preanesthetic medication in adults. Many authors have reported the effects of intravenous clonidine pretreatment on the hemodynamic responses to tracheal intubation, on the anesthetic requirements during the operation and on postoperative analgesia in adults. The current study was designed to investigate the efficacy of two doses of intravenous clonidine as a premedicants.

In a prospective, randomized, double-blind, controlled clinical trial, 60 children, aged 5 12 years, undergoing an elective adenotonsillecctomy received saline, 1 microgram/kg clonidine or 2 microgram/kg clonidine intravenously. These agents were administered 10 minutes before the estimated time of induction of anesthesia with intravenous atropine 0.01 mg/kg. A blinded observer noted the childrens'levels of sedation, the quality of separation from parent, and degree of acceptance of mask application during the inhalation of 100% oxygen just after pentothal sodium injection. Hemodynamic changes after tracheal intubation were compared among the three groups.

Clonidine produced significant sedation, and this effect were dose related. The clonidine administered groups provided a better quality of separation than the control group. Amnesia about mask application was significantly higher in the clonidine 2 microgram/kg administered group. These doses of clonidine did not attenuate increases in blood pressure and heart rate after tracheal intubation. No consistent differences in the blood pressure or heart rate after tracheal intubation were observed in the three groups. No clinically significant perioperative hypotension or bradycardia was observed.

These data indicate that, the combination of intravenous 1 microgram/kg clonidine or 2 microgram/kg clonidine with atropine 0.01 mg/kg is an effective form of premedication in pediatric surgery. However, the optimal dose of clonidine for both sedation and hemodynamic stability after tracheal intubation in this setting remains to be determined.