Efficacy of granisetron in preventing postanesthetic shivering

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.

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.

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).

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.