A prospective randomised comparative study of intrathecal buprenorphine versus intrathecal magnesium sulphate as an adjuvant to 0.5% hyperbaric bupivacaine for lower limb surgeries under subarachnoid block

Background: Spinal anaesthesia can be strengthened and improved postoperative analgesia can be achieved by adding an adjuvant to a local anaesthetic. The objective of this study is to assess the onset and duration of sensory and motor block, duration of analgesia and to compare the efficacy of 0.5 percentage of hyperbaric bupivacaine with magnesium sulfate to that of 0.5 percentage of hyperbaric bupivacaine in conjunction with buprenorphine during surgeries of the lower limb. Methods: A total of 60 ASA 1 and 2 patients undergoing lower limb surgeries under spinal anaesthesia, were randomly divided into two groups (30 each). Group B was administered a 15mg dose of a 0.5% heavy bupivacaine solution, in conjunction with 1 mcg/kg buprenorphine, as an adjuvant. Conversely, Group M received the same dosage but was additionally infused with 0.5 ml (50 mg) of magnesium sulfate (Total 3.5 ml) The subarachnoid block was performed in the interspace between the L3-L4 vertebrae following a confirmed cerebrospinal fluid (CSF) flow in the seated position. The onset of analgesic effect, degree of blockade, sedation score, duration of analgesia, occurrence of adverse effects and hemodynamic parameters were all meticulously monitored. Results: The findings of this study revealed no significant disparities in age, sex, weight or the mean duration of surgery across the two groups. Furthermore, there was no significant difference in the time required for the onset of motor block between the study groups (p>0.05). Mean duration of sensory block (141.83 vs 90.0 mins; p<0.01) and motor block (267.8 vs 218.1; p<0.01) was significantly more in cases of magnesium sulphate group as compared to buprenorphine group. Mean duration of analgesia (294.83 vs 245.5; p<0.01) was significantly more in cases of magnesium sulphate group as compared to buprenorphine group. Conclusions: A good analgesia is achieved by magnesium sulphate as compared to buprenorphine when added to 0.5% hyperbaric bupivacaine for lower limb surgeries. Depth of sensory block was greater with magnesium sulphate.