PREMEDICATION WITH ORAL AND TRANSDERMAL CLONIDINE PROVIDES SAFE AND EFFICACIOUS POSTOPERATIVE SYMPATHOLYSIS

We studied 61 patients undergoing elective major noncardiac surgery in a randomized, double-blind, placebo-control clinical trial to test th e hypothesis that the addition of clonidine to a standardized general anesthetic could safely provide postoperative sympatholysis for patien ts with known or suspected coronary artery disease. Patients were allo cated randomly to receive either placebo (n = 31) or clonidine (n = 30 ). The treatment group received premedication with a transdermal cloni dine system (0.2 mg/d) the night prior to surgery, which was left in p lace for 72 h, and 0.3 mg oral clonidine 60-90 min before surgery. Clo nidine reduced enflurane requirements, intraoperative tachycardia, and myocardial ischemia (1/28 clonidine patients vs 5/24 placebo, P = 0.0 5). However, clonidine decreased heart rates only during the first fiv e postoperative hours; the incidence of postoperative myocardial ische mia (6/28 clonidine vs 5/26 placebo) did not differ between the two gr oups. Patients who experienced postoperative myocardial ischemia tende d to have higher heart rates after surgery. Clonidine significantly re duced the plasma levels of epinephrine (P = 0.009) and norepinephrine (P = 0.026) measured on the first postoperative morning. There were no differences in the need for intravenous fluid therapy or antihyperten sive therapy after surgery. The number of hours spent in an intensive care setting and the number of days spent in hospital were not differe nt between the two groups. These results suggest that larger doses of clonidine should be investigated for their ability to decrease postope rative tachycardia and myocardial ischemia.