Efficacy of Adding Magnesium Sulfate to Bupivacaine for Ilioinguinal and Iliohypogastric Nerve Block in Acute Postherniorrhaphy Pain

Regional block of ilioinguinal and iliohypogastric (IIIH) nerves has been applied to provide postoperative analgesia after inguinal hernia repair. Magnesium sulfate (MgSo4) blocks N-methyl-d-aspartate receptors, and that is why, it was used as an adjuvant to the local anesthetic (LA) in different anesthetic approaches. Although the prolongation in postoperative duration resulting from the addition of MgSO4 to LA was significant in some literature studies, it was insignificant in others. This study was designed to investigate the adjunctive effect of MgSo4 when added to bupivacaine for IIIH blockade on the postoperative analgesic duration as a primary outcome and on the verbal rating scale (VRS) scores, analgesic consumption, and hemodynamics as secondary outcomes. Patients were divided into two groups of 45 patients each by means of coded envelopes according to the LA used for IIIH blockade. In the first group (control group), patients received 10 ml 0.5% isobaric bupivacaine plus 1 ml normal saline for IIIH blockade, whereas in the second group (MgSo4 group), 10 ml 0.5% isobaric bupivacaine and 1 ml of MgSo4 10% were prepared. All the patients received intrathecal 3 ml 0.5% hyperbaric bupivacaine, and then, IIIH blockade was performed under ultrasound guidance according to the group. Postoperatively, VRS scores,analgesic duration, and any complication were recorded.