Evaluating the Efficacy of MgSO4 as an Adjuvant to 0.5% Bupivacaine in Supraclavicular-Intercostobrachial Nerve Blocks for Upper Extremity Hemodialysis Vascular Access Surgery

Abstract

Background
Peripheral nerve blocks are a preferred anesthetic technique in patients with renal failure undergoing hemodialysis vascular access. A limitation of this technique is the long onset time required to achieve total sensory and motor block. The use of the adjuvant magnesium sulfate (MgSO4) is believed to address this limitation and enhance the effectiveness of the block.
Objective
To evaluate the effectiveness of using MgSO4 20% 2000 mg as an adjuvant in the supraclavicular-intercostobrachial nerve block to expedite the onset time necessary to achieve total sensory and motor block and to prolong the duration of analgesia in patients undergoing upper extremity hemodialysis vascular access surgery. The hypotheses are as follows: 1) MgSO4 as an adjuvant reduces intraoperative fentanyl requirements due to enhanced analgesic effects; 2) MgSO4 decreases perioperative NLR, reflecting reduced systemic inflammation; and 3) MgSO4 modulates PLR, indicating its potential role in controlling platelet activation and inflammatory response.
Methods
This study utilized a randomized controlled trial design with an open-label approach involving 28 patients undergoing upper extremity hemodialysis vascular access surgery at RSUP Prof. I.G.N.G. Ngoerah. Subjects were divided into two groups: one receiving the adjuvant MgSO4 20% 200 mg and the other without adjuvant. Patients were then evaluated for the time required to achieve total sensory block, time to reach total motor block, and the duration of analgesia.
Results
Among the 28 participants analyzed, the group receiving the MgSO4 adjuvant showed a faster time to reach total sensory block, total motor block, and extended duration of analgesia from the nerve block. In the group with MgSO4, the average time to achieve total sensory block was 10.08 ± 0.90 minutes, compared to 17.19 ± 1.85 minutes in the group without adjuvant. For total motor block, the group with MgSO4 had an average time of 17.98 ± 1.26 minutes, whereas the group without adjuvant had an average of 25.19 ± 2.22 minutes. Additionally, the group using MgSO4 had an average duration of analgesia of 473.43 ± 28.69 minutes, compared to 266.5 ± 22.79 minutes in the non-adjuvant group.
Conclusion
The use of MgSO4 20% 200 mg as an adjuvant in the supraclavicular-intercostobrachial nerve block accelerates the onset time of sensory block, motor block and prolongs the duration of analgesia from the block.