The Effect of Ondansetron in Prevention of Postoperative Shivering after General Anesthesia in Gynecological Surgery

Dear Editor, Shivering happens frequently in 5 to 60% of surgical operations. 1 Though it occurs as a result of temperature reduction, it may occur in patients with a post-operative normal body temperature. 2 Shivering may be dangerous due to increasing effect of medicines, extension of recovery period, increased oxygen consumption or hemostatic dysfunction especially in patients with a low cardiac reserve. 3 Several medications have been suggested for prevention and treatment. According to regulator effect of intra-hypothalamic serotonin (5-ydroxytryptamine), its agonists (ondansetron) are reported to have the same effect. 4 Opposed to meperidine, ondansetron may reduce post-operative nausea and vomiting (PONV). 5 A medication to reduce both PONV and shivering will be very valuable. 6 This study evaluated preventive effect of ondansetron and meperidine on post-operative shivering compared to a control group. We did this study in Alavi University Hospital of Ardabil (IRAN) in 2008. The protocol was approved by ethical committee of this university. All patients were in ASA physiologic class I or II. Patients were randomly selected to receive either 4 mg ondansetron, 0.4 mg/kg meperidine or 2 ml normal saline (the placebo) 2 minutes before inducting anesthesia. We induced anesthesia by 1µg/kg fentanyl, 5 mg/kg thiopental and 1 mg/kg succinylcholine continued by 0.8-1% isoflurane along with the inspiration mixed of 50% oxygen and 50% N 2 O after intubation. Room temperature was set at 20-22°C. We measured core body and skin temperature through tympanic membrane and forehead accordingly. Patients were observed for shivering (chills for at least 15 seconds), nausea or vomiting during recovery by an anesthesiologist blinded to the medication. Patients received appropriate care by meperidine for shivering and metoclopramide for nausea or vomiting when necessary. Data were statistically analyzed using SPSS software (version 15, Chicago, IL, USA). All data were expressed as the mean±SD. A repeated-measure ANOVA was used for comparing core body temperature , skin temperature, systolic and diastolic blood pressure and heart rate in several stages (basic, post-induction of anesthesia, end of surgery and in recovery room) in each group and Chi-Square test wase used for comparing the prevalence of shivering, nausea and vomiting in each group. A p-value less than 0.05 was considered significant. There was no significant difference in age (p=0.49), operation duration (p=0.34), core body temperature (p=0.76) and skin temperature (p=0.79) between the groups. Core body temperature decline in control group was more in patients receiving ondansetron or meperidine …