Evaluation of adding magnesium sulphate to intrathecal bupivacaine in lower limb orthopedic surgery

Abstract Background A subarachnoid block is the cheaper and widely used regional block for lower limb surgery. Postoperative pain occurs after lower limb orthopedic surgery from moderate to severe. We conducted a prospective, randomized, double-blind controlled trial. All patients were assessed for onset and duration of sensory and motor block, total duration of analgesia, and postoperative pain relief. This study was conducted to evaluate the efficacy of intrathecal bupivacaine with magnesium undergoing lower limb orthopedic surgery. Results One hundred patients were randomly divided into two equal groups. Group M: Intrathecal 3 ml (15 mg) of 0.5% bupivacaine + 0.2 ml (50 mg) of preservative-free 25% of magnesium sulphate. Group B: Intrathecal 3 ml (15 mg) of 0.5% bupivacaine + 0.2 ml preservative-free 0.9% normal saline. The mean time that occurred for the sensory blockade at T10 was 2.49 ± 0.49 min in group B, while it was 4.13 ± 0.74 min in group BM ( p value < 0.0001). The mean of the total duration of the sensory block in group B was 139.5 ± 32.01 min, while it was 366.4 ± 30.12 min in group BM ( p value < 0.0001). The time taken for the onset of motor block in group B was 5.28 ± 1.31 min, while it was 7.86 ± 1.19 min in group BM ( p value < 0.0001). The mean total duration of the motor block in group B was 136.3 ± 8.19 min, while it was 336.5 ± 37.08 min in group BM ( p value < 0.0001). The total duration of analgesia in group B was 141.4 ± 14.85 min, while it was 365.9 ± 44.91 min in group BM ( p value < 0.0001). The mean dose required for rescue analgesia in group B was 2.2 ± 1.14, while in group BM was 1.28 ± 0.96 ( p value < 0.0001). Conclusions The addition of 50 mg magnesium sulphate in intrathecal hyperbaric bupivacaine significantly prolongs the extended duration of sensory, motor blockade, and total duration of analgesia for patients undergoing lower limb orthopedic surgery.