RESUMEN
As an alphs-2 adrenergic agonist, clonidine, which is an antihypertensive drug, can reduce central sympathetic outflow. By regulation of presynaptic transmitter release, it also lowers blood pressure and amounts of anesthetic drugs used during anesthesia, causes sedation, and attenuates postoperative shivering. The authors studied the effects of transdermal clonidine as a premedicant, which is easy and simple to use and maintains constant plasma level. Sixty patients undergoing elective orthopedic surgery, with preoperative normal blood preesure, were seleeted and randomly divided into 2 groups, 30 subjects each. Placebo patch was placed on the shoulder of patients belonging to the placebo group, and clonidine patch for the clonidine group just 48 hours before operation. Cardiovascular effects such as changes in perioperative blood pressure and heart rate, the degree of sedation before to induction, amounts of anesthetic drugs during anesthesia, postoperative analgesic requirements, ratio of patients who experienced postoperative shivering were observed and compared between the two groups. Patients in the clonidine group showed more stable cardiovascular response perioperatively and amounts of anesthetic drugs required during operation were reduced as compared to the placebo group(p<0.05). Preinduction sedation score of clonidine group was definitely higher than that of placebo group. (p <0.05) All 30 patients in the placebo group required analgesics for 48 hours after operation(100%) and only 19 patients of the clonidine group required analgesics(63%). The amounts of postoperative analgesics were definetely reduced in the clonidine group(p<0.05). Postoperative shivering occurred in 12 patients of the placebo group(40%) and 5 patients of the clonidine group(16.6%). We concluded that transdermal clonidine can be used effectively as a premedicant privided close regulation of anesthetic drugs used during anesthesia is possible.