---

Background & aim: Shivering is one of the complications after spinal anesthesia. There are different ways to control it. Therefore, the aim of this study was to determine the efficacy of two different doses of ketamine and midazolam in preventing shivering after spinal anesthesia.
Methods: The present study was a double blind clinical trial. The study population consisted of 120 patients undergoing spinal anesthesia surgery referred to Alzahra Hospital during 2016-2017. Patients were randomly divided into three groups of A, B and C, group A was received 0.02 mg / kg midazolam at low dose with 0.3 mg / kg of ketamine.  Group B was received 0.04 mg / kg midazolam at normal dose with 0.15 mg / kg of Ketamine at low dose and group C received normal saline in equal volume before surgery. Demographic data, severity of shivering, and need for analgesics were evaluated. Data were analyzed using one-way ANOVA, independent t-test, Kruskal-Wallis, Friedman, Wilcoxon tests.
Results: The mean arterial blood pressure was significantly lower in group A after intervention than in group B and C. The intensity of shivering in group C was significantly higher than the other two groups (p<0.05). No significant difference was seen between groups B and C based on shivering intensity (p<0.05). Also recovery time in group B was significantly longer than group A and C (p<0.05).
Conclusion: Ccombination of both midazolam and ketamine are suitable for reducing shivering, but the use of low dose midazolam plus ketamine seems to be better than low dose ketamine plus midazolam in terms of hemodynamic stability and shorter recovery time.