The effects of different doses of intrathecal meperidine on the incidence and severity of shivering during lower extremity orthopedic surgery under spinal anesthesia: A randomized, placebo-controlled, double blind-clinical trial

BACKGROUND: Shivering associated with spinal anesthesia is a common complication. It also causes more usage of oxygen, increased production of carbon dioxide (CO2), and lactic acidosis with movement of clots and bleeding after surgery. This study was performed to compare the different dosages of intrathecal meperidine and their effects on shivering during and after surgery and to compare these to the control group. MATERIALS AND METHODS: This study is a clinical trial. Target population consisted of the patients who were candidates for lower limb orthopedic surgery under spinal anesthesia. About 120 patients were chosen and randomly divided into four groups. In group 1, spinal anesthesia was performed with 3 ml marcaine 0.5% and 0.1 mg/kg meperidine. In group 2, 3 ml marcaine 0.5% and 0.2 mg/kg meperidine was given. In group 3, 3 ml marcaine 0.5% and 0.3 mg/kg meperidine, and in the fourth group, 3 ml marcaine 0.5% and normal saline in the same volume were injected. During surgery and recovery, hemodynamic index and shivering were recorded. RESULTS: Based on the analyzed data, in the fourth group 23 patients (76.7%) had shivering. While the prevalence of shivering in the first, second, and third groups was 15 patients (50%), 11 patients (36.7%), and 3 patients (10%), respectively. Chi-square test showed significant difference in the four groups (P < 0.001). CONCLUSIONS: Using higher dosage of intrathecal meperidine (0.3 mg/kg) was more effective than using lower dosage of meperidine (0.1 mg/kg and 0.2 mg/kg) in reducing the incidence and severity of shivering during spinal anesthesia in lower extremity orthopedic surgeries.