Intrathecal Tramadol for Prevention of Postanesthesia Shivering after Subarachnoid Block: A Prospective Randomized Placebo-Controlled Comparison of Two Different Doses (10 and 20 mg)

BACKGROUND: Shivering is a common and distressing complication following subarachnoid block (SAB). Literature comparing the antishivering efficacy of different doses of intrathecal (IT) tramadol is lacking. AIMS: This prospective randomized controlled study was undertaken to evaluate and compare the antishivering efficacy of IT tramadol 10 and 20 mg. METHODS: Ninety adult patients undergoing lower limb orthopedic surgeries under SAB were randomized into three groups (n = 30) to receive IL 0.5% hyperbaric bupivacaine 3 ml with tramadol 0 mg (Group C), 10 mg (Group T10), or 20 mg (Group T20) in normal saline. Shivering was assessed using a 5-point intensity scoring system intraoperatively and up to 4-h postoperatively. The onset and duration of sensory and motor block, duration of analgesia, and adverse effects were assessed. STATISTICAL ANALYSIS USED: Analysis of variance and Pearson Chi-square test were used for statistical analysis. RESULTS: The incidence and intensity of shivering were significantly reduced in Group T10 versus C (incidence, P = 0.007; intensity, P = 0.002) and T20 versus C (incidence, P < 0.001; intensity, P < 0.001) but comparable among groups T10 and T20 (incidence, P = 0.133; intensity, P = 0.142). There was a significant dose-dependent prolongation of duration of sensory block (121, 137, and 150.5 min; P = 0.001), motor block (242.83, 298.5, and 344 min; P < 0.001), and analgesia (289.17, 357, and 404.67 min; P < 0.001) with escalating doses of IT tramadol, respectively. All the groups were comparable with respect to hemodynamic variables, core temperature, and adverse effects. CONCLUSION: The addition of tramadol 10 or 20 mg IT to 0.5% hyperbaric bupivacaine for SAB is associated with significant reduction in the incidence and intensity of postanesthesia shivering and prolongation of the duration of postoperative analgesia. Tramadol 20 mg IT compared to 10 mg IT significantly prolonged the duration of postoperative analgesia but failed to demonstrate any significant attenuation of postanesthesia shivering.