Premedication with Oral and Transdermal Clonidine Provides Safe and Efficacious Postoperative Sympatholysis

Comment: Clonidine is a central α-2 agonist that decreases nerve conduction in A-a and C fibers. Previous studies have demonstrated that clonidine decreases minimum alveolar concentrations of anesthetics and decreases intraoperative tachycardia and hypertension. This study demonstrates that postoperative heart rate is also decreased by clonidine compared with placebo for the first 5 hr. The authors suggest mat higher doses may prolong these effects further, into the postoperative period. This is important because such medications may alter the incidence of postoperative ischemia, particularly in hypertensive patients. Unfortunately, this study did not compare clonidine with other methods of controlling heart rate and providing sedation postoperatively. It is, therefore, unknown if clonidine offers any advantage over other techniques. Clonidine has significant disadvantages because it is long acting and is associated with significant hypotension and bradycardia.