Minimum effective dose of Tramadol in the treatment of postanesthetic shivering

Abstract

• BACKGROUND: To determine the minimum effective dose of intravenous administration of tramadol on controlling postanesthetic shivering (PAS) and frequency of effects.
• METHODS: Seventy five patients who had shivering grade III or IV after general anesthesia with isoflurane in the recovery room were included in the study. The patients were divided randomly among five groups to receive the same dose of tramadol: 0.2 mg/kg, 0.4 mg/kg, 0.6 mg/kg, 0.8 mg/kg and 1 mg/kg. The shivering grades, tympanic temperature immediately prior to administering the treatment, time spent to control shivering, shivering relapse, time interval between the two shivering periods and side effects were registered. Data were analyzed with SPSS software, version 14. Chi-square test, t-student test and analysis of variance were used where they were appropriate. P value < 0.05 was considered significant.
• RESULTS: There were no statistically significant differences among treatment groups with respect to demographic data, duration of anesthesia, room temperature of postanesthesia care unit, shivering grade before treatment and central temperature at the time of treatment. There was no significant difference among the number of patients who stopped shivering with 0.2 mg/kg compared with 1 mg/kg of tramadol. There was no significant difference among the five doses for shivering relapse. Frequency distributions of side effects were not different among the five groups.
• CONCLUSIONS: All patients completely stopped shivering with tramadol 0.4 mg/kg or more in 5 minutes after treatment. With 0.2 mg/kg only 80% of patients stopped shivering. Although the difference between 0.2 mg/kg and 1 mg/kg was not statistically significant, because of the limited number of cases we were not able to reject type two errors. According to this study, we suggest 0.4 mg/kg of tramadol for shivering control
• KEY WORDS: Tramadol, postanesthetic shivering, minimum effective dose.