Comparative Study of Analgesic Effect of Intrathecal Magnesium Sulphate, Clonidine and Dexmedetomidine as an Adjunct to Intrathecal Bupivacaine in Spinal Anesthesia for Lower Limb Orthopaedic Surgeries

Abstract

This prospective double blind, randomized controlled trial study was undertaken to compare the onset and duration of analgesia with the intrathecal bupivacaine and its combination with either clonidine or magnesium sulphate or dexmedetomidine, to establish the ideal combination of drug with least side effects. The study included 80 patients between age group 20–60 years of ASA grade I & II, scheduled for orthopaedic lower limb surgery. Patients were randomly assigned to four groups of 20 patients each. Gr.A- 3 ml of 0.5% bupivacaine + 1ml of NS, Gr.B- 3 ml of 0.5% bupivacaine + clonidine 30 mcg + 1 ml of NS, Gr.C- 3 ml of 0.5% bupivacaine + magnesium sulphate 50 mg + 1 ml of NS  and Gr. D-3 ml of 0.5% bupivacaine + dexmedetomidine 3 mcg + 1 ml of NS. The time of injection, onset of analgesia, sensory and motor block, hemodynamic changes and side effects were recorded. The time of onset of sensory analgesia is least with clonidine, the time of regression of sensory analgesia to L1 segment is maximum with clonidine, time for onset of motor block is least in clonidine group, hemodynamic effects and side effects were not significant. We concluded that we have quicker time of onset of sensory and motor blockade , greater duration of analgesia, with no significant increase in side effects with clonidine group than the magnesium sulphate group or dexmedetomidine group.

Keywords: Analgesia, Orthopaedic and Spinal surgery, Lower limb