Efficacy of granisetron in preventing postanesthetic shivering

Abstract

Background: Recently, 5-hydroxytryptamine 3 (5-HT3) receptor antagonists have been reported to prevent postanesthetic shivering. This placebo-controlled study was performed to evaluate the efficacy of granisetron, a 5-HT3 antagonist, in comparison with meperidine and tramadol in preventing postanesthetic shivering.

Methods: In this prospective, randomized, double-blind study, 132 ASA I and II patients undergoing elective orthopedic surgery under standardized general anesthesia were included. At the end of surgery, patients were randomly assigned to one of four groups (each group n = 33) using a double-blinded protocol. Group T received 1 mg/kg tramadol, group G received 40 microg/kg granisetron (an antiemetic dose), group M received 0.4 mg/kg meperidine, and group P received saline 0.9% as placebo. Shivering was graded according to the following: 0 = no shivering; 1 = piloerection, peripheral vasoconstriction or peripheral cyanosis without other cause; 2 = visible muscular activity confined to one muscle group; 3 = visible muscular activity in more than one muscle group; and 4 = gross muscular activity involving the entire body. The emergence time from anesthesia, defined as the time between withdrawal of isoflurane and tracheal extubation, was documented.

Results: The number of patients with observable shivering was 19 in group P, nine in group G, seven in group T and six in group M. Granisetron significantly reduced the incidence of shivering in comparison with placebo (p = 0.013). Although the frequency of shivering was higher with granisetron in comparison to tramadol and meperidine, it was not statistically significant (p > 0.05). The number of patients with a shivering score of 2, 3 and 4 was significantly higher in group P compared with the other groups (p = 0.001). Both meperidine and tramadol caused a significantly prolonged emergence time (20.58 +/- 3.56 and 16.45 +/- 4.13 minutes, respectively) as opposed to granisetron (13.58 +/- 3.41 minutes) and placebo (12.61 +/- 3.31 minutes).

Conclusion: The prophylactic use of granisetron 40 microg/kg is as effective as meperidine (0.4 mg/kg) and tramadol (0.1 mg/kg) in preventing postanesthetic shivering without prolonging the emergence time from anesthesia.