A comparison of urapidil, clonidine, meperidine and placebo in preventing postanesthetic shivering

This placebo-controlled study was performed to evaluate the efficacy of ura pidil compared with clonidine and meperidine in preventing postanesthetic s hivering, which is common after anesthesia administration and may be very d istressing. We studied 120 patients undergoing elective abdominal or orthop edic surgery under standardized general anesthesia. After surgery, patients were randomly assigned to one of four groups (each group n = 30) using a d ouble-blinded protocol: Group A received 0.2 mg/kg urapidil; Group B, 3 mu g/kg clonidine; Group C, 0.4 mg/kg meperidine; and Group D, saline 0.9% as placebo. Postanesthetic shivering was scored by using a five-point scale. C lonidine and meperidine significantly reduced the incidence and the severit y of shivering in comparison with placebo, whereas there were no significan t differences between the urapidil and placebo groups. Both clonidine and m eperidine caused a significantly prolonged emergence time (13.4 +/- 5.8 and 13.3 +/- 5.0 min, respectively) compared with placebo (10.4 +/- 5.3 min) a nd urapidil (11.4 +/- 2.9 min). We confirmed that both clonidine and meperi dine are effective in preventing postanesthetic shivering, whereas urapidil , in our setting and dosage, was not effective. Patients who received cloni dine or meperidine had a prolonged emergence time. In the dosage used, urap idil seems to be unable to prevent postanesthetic shivering. Implications: Shivering (irregular muscle activity) is common after surgery and anesthesi a. This study compared urapidil (an antihypertensive drug) as a prophylaxis with two established antishivering drugs (meperidine and clonidine) and pl acebo. In the dosage used, we were unable to show a significant benefit of urapidil.