Urapidil does not prevent postanesthetic shivering: a dose-ranging study

Purpose: To investigate the effect of 0.2 mg.kg(-1), 0.3 mg.kg(-1) and 0.4 mg.kg(-1) urapidil on the incidence and severity of postanesthetic shiverin g. Methods: One hundred and fifty patients (ASA I-III) scheduled for elective abdominal, urologic or orthopedic surgery under standardized general anesth esia were randomly allocated to one of five groups (each group n=30) using a double-blind protocol: group A received 0.2 mg.kg(-1) urapidil, group B: 0.3 mg.kg(-1) urapidil, group C: 0.4 mg.kg(-1) urapidil, group D: 3 mug.kg( -1) clonidine (positive control group), and group E: saline 0.9% as placebo (negative control group). Postanesthetic shivering was scored using a five -point scale. Results: Twelve patients of group A, I I of group B, nine of group C, three of group D and 14 of group E showed signs of postanesthetic shivering. Pos tanesthetic shivering was significantly decreased in the clonidine group co mpared to the three urapidil groups and the placebo group. Significantly le ss patients treated with clonidine needed anti-shivering therapy. There wer e no significant differences between the urapidil and placebo groups. Thera peutic interventions for hemodynamic effects were not required in any group . Time to extubation, but not time to discharge, was prolonged in the cloni dine group. Conclusion: Urapidil showed no beneficial effect on shivering in any of the doses evaluated, whereas prophylactic administration of clonidine was effe ctive in preventing postanesthetic shivering.