Effect of Ondansetron on Postoperative Shivering After Craniotomy.

INTRODUCTION Postoperative shivering (POS) is an early complication after craniotomy. Preventive pharmacologic drugs are the mainstay of treatment. Meperidine is the drug of choice but with increased risk of apnea, nausea, and increased intracranial pressure. Some reports have suggested that ondansetron and meperidine have similar anti-shivering effects. OBJECTIVES To assess the preventive effect of ondansetron on POS after craniotomy. METHODS In a randomized, double-blind, placebo-controlled trial, 80 patients with American Society of Anesthesiologists status I to II between 20 and 60 years of age scheduled for elective craniotomy were enrolled in the study. Patients received either intravenous ondansetron 4 mg (n = 40) or saline (n = 40) 10 minutes before the end of surgery. RESULTS POS was observed in 3 patients (7.5%) in the ondansetron group, significantly lower than in the control group (6 patients [15%]; P =0.048). Ondansetron decreased the relative risk of occurrence of POS after craniotomy from 4.42 (95% confidence interval [CI], 2.3-8.5; P = 0.0021) in the control group to 1.05 (95% CI, 0.76-2.20; P = 0.074). In the ondansetron group, the mean (± standard deviation) core temperature in the preoperative phase (36.6°C ± 0.66°C) was significantly higher than in the postoperative phase (34.2°C ± 0.56°C) (P = 0.001). In addition, the mean (± standard deviation) peripheral temperature in the preoperative phase (36.5°C ± 0.72°C) was significantly higher than in the postoperative phase (34.4°C ± 0.51°C) (P = 0.001). CONCLUSIONS Ondansetron can effectively decrease POS after craniotomy. This effect is not mediated through maintenance of the core or peripheral temperature. Ondansetron probably acts by a central inhibitory mechanism on POS through 5-hydroxytryptaminergic pathways, not by changing thermoregulatory set points.