CLONIDINE AND KETANSERIN BOTH ARE EFFECTIVE TREATMENT FOR POSTANESTHETIC SHIVERING

Background. Although meperidine is an effective treatment of postanest hetic shivering, its mechanism of action remains unknown. Investigatio n of other drugs might help clarify the mechanisms by which shivering can be controlled. Accordingly, we investigated the efficacy of clonid ine, an alpha2-adrenergic agonist, and ketanserin, a 5-hydroxytryptami ne antagonist, in treating postanesthetic shivering. Methods: First, 5 4 patients shivering after general anesthesia were allocated randomly to receive an intravenous bolus of saline, 150 mug clonidine, or 10 mg ketanserin. A second study explored the dose-dependence of clonidine. Forty shivering patients were given saline or clonidine, 37.5, 75, or 150 mug. Results: The duration of shivering was significantly shorter in those given clonidine (2.1 +/- 0.9 min) than in the other two grou ps and shorter in the ketanserin group (4.3 +/- 0.9 min) than in the s aline group (12.0 +/- 1.6 min). Clonidine and ketanserin significantly decreased systolic arterial blood pressure when compared to saline. C ore rewarming was significantly slower in the clonidine group. In the second study, 37.5 mug clonidine was no more effective than saline. Tw o minutes after treatment, 150 mug obliterated shivering in all patien ts. Five minutes after treatment, all patients given 75 mug had stoppe d shivering. Systolic arterial pressure and heart rate decreased signi ficantly in patients given 75 and 150 mug clonidine. Conclusions. Clon idine (150 mug) and ketanserin (10 mg) both are effective treatment fo r postanesthetic shivering. The effect of clonidine on shivering is do se-dependent: whereas 37.5 mug had no effect, 75 mug clonidine stopped shivering within 5 min.