[The effects of low dose clonidine on perioperative hemodynamics and anesthetic requirements in elderly patients]

The effects of clonidine, alpha 2-adrenergic receptor agonist, on perioperative hemodynamics and anesthetic requirements were studied in randomized 20 elderly patients without hypertension (ASA I-II) scheduled for elective abdominal surgery under general anesthesia. The control group (n = 10) was premedicated with oral diazepam 0.1 mg.kg-1 90 min prior to arrival in the operating room. The clonidine group (n = 10), in addition, received clonidine approximately 2.5 micrograms.kg-1 orally at the same time. Anesthesia was induced with fentanyl 2 micrograms.kg-1 and thiamylal 4 mg.kg-1. Vecuronium 0.15 mg.kg-1 following 0.01 mg.kg-1 priming dose was used to facilitate endotracheal intubation. Anesthesia was maintained with isoflurane in 50% nitrous oxide-oxygen and supplementary fentanyl. Clonidine effectively attenuated the cardiovascular response associated with laryngoscopy and tracheal intubation. Intraoperative variability of heart rate was significantly lower in patients receiving clonidine compared with controls. No significant differences in the requirements of either isoflurane or narcotic supplementation were observed between the two groups. We conclude that a low dose clonidine is a useful adjunct in the management of elderly patients without producing side effects.