^1,3Department of Anaesthesia, Civil Hospital Theog, Shimla, Himachal Pradesh, INDIA.

²Department of Anaesthesia DDU Zonal Hospital Shimla, Himachal Pradesh, INDIA.

⁴S.R, Department of Obstetrics & Gynaecology, KNH Shimla, Himachal Pradesh, INDIA.

Email: priyanshusharma27@gmail.com

Modified Bromage Scale

The duration of block was defined as the onset of block from the first rescue analgesia requirement. Mean arterial pressure (MAP), heart rate (HR) and respiratory rate (RR) were monitored in each group upto 12 hours postoperatively. Standard post-operative care was provided. All findings were entered in Microsoft excel sheet and the results were analysed with SPSS version 22. Results were evaluated using statistical test (chi-square test and independent T test). p value less than 0.05 was considered as statistically significant.

RESULTS

In present study 30 patients each were randomly allocated group M and group P. General characteristics such as age, gender and ASA status were comparable in both groups.

Table 1: General characteristics

The onset for sensory block for group M was 9.47 ± 2.60 min, in group P was 13.57 ± 3.48 min and difference was highly significant (p value < 0.001). The mean duration of block in group M was 8.48 ± 1.64 hrs and in group P was 5.55 ± 0.86 hrs with p values < 0.001 which was highly significant. The mean value of motor blockade was graded according to Modified bromage scale for group M was 2.56 ± 0.50 and for group P was 2.70 ± 0.47, difference was not significant. The mean duration of demand of rescue analgesia in group M was 8.48 ± 1.64 hrs. and in Group P was 5.55 ± 0.86 hrs. with highly significant p values of <0.001. Heart rate, mean arterial pressure, Respiratory rate was monitored in each group in intraoperative and postoperative period upto 12 hrs. and were comparable between two groups at all time intervals.

Table 2: Intra-operative and post-operative findings

Patients were observed for any side effects intraoperatively and postoperatively such as nausea, vomiting, local trauma, giddiness, bradycardia and tachycardia. In our study no patients in group M complained of nausea and 2 complained of giddiness and in group P, 2 patients complained of nausea and one of giddiness.

Table 3: Side Effects

DISCUSSION

The axillary approach to brachial plexus blockade provides satisfactory anaesthesia for elbow, forearm, and hand surgery and also provides reliable cutaneous anaesthesia of the inner upper arm including the medial cutaneous nerve of arm and inter costobrachial nerve, areas that are often missed with other approaches.⁶ In addition, the axillary approach remains the safest of the four main options, as it does not risk blockade of the phrenic nerve and it does not have the potential to cause pneumothorax, making it an ideal option for day care surgery.⁷ The role of NMDA receptor in pain transmission has long been understood. Blocking NMDA subtype of glutamate receptors reduce the afferent stimulation of spinal cord and therefore blocking the pain transmission. Magnesium sulphate has known to inhibit nociception through its NMDA receptor antagonistic properties making it a suitable adjuvant for brachial plexus block with local anaesthetic drug.⁸ In present study patients receiving 0.375 % bupivacaine with 250 mg MgSO4 had early onset of sensory block and duration of block was prolonged as compared to the group receiving plane bupivacaine. Similar findings were noted by Verma V et al.⁹ Kasturi Mukherjee et al.,¹⁰ studied elective forearm and hand surgeries in 100 patients, randomly and in double blind fashion divided into group RM (30ml 0.5% ropivacaine plus 150mg MgSO4) and in group RN (30ml 0.5 % ropivacaine plus 1ml NS). They noted that duration of sensory block was increased in group RM, similar to present study. While time of onset of sensory blockade was slightly increased in group RM, where as in present study onset of sensory blockade was reduced in magnesium group as compared to plain bupivacaine group. Haghighi M et al.,¹¹ investigated the effect of magnesium sulphate to lidocaine to extend the duration of sensory and motor blocks of the axillary plexus in orthopedic surgeries of the upper extremities and concluded that the addition of magnesium sulphate increases the duration of motor and sensory block as compared to the use of lidocaine alone. Gunduz A, et al.,¹² studied the effect of the addition of magnesium in 60 patients scheduled for forearm and hand surgeries under axillary brachial plexus block. They concluded that addition of magnesium sulphate to 2% prilocaine for axillary brachial plexus block provided marked prolongation of sensory and motor blockade. In a study by Reza akhondzade et al.,¹³ investigated effect of adding magnesium sulfate to lidocaine on postoperative pain in upper limb surgeries by supraclavicular brachial plexus block under ultrasound guidance and concluded that postoperative VAS values at 24 hours were significantly lower in group M (lidocaine 1% +fentanyl 50 µg + magnesium sulphate 20% 5ml) than group N (lidocaine + 50µg fentanyl + normal saline 5ml). Sensory and motor block onset and duration were also statistically longer in group M than in group N. Gyu Choi et al.,¹⁴ studied patients undergoing upper extremity surgery as 0.2% ropivacaine 20 ml with normal saline 2 ml versus 0.2% ropivacaine 20 ml with MgSO4 200 mg via axillary brachial plexus block just before extubation. The post-operative visual analogue scale (VAS), opioid consumption and side effects were recorded. The results of this study showed no difference in VAS scores and no statistically significant difference in opioid consumption between the two groups. Side effects were recorded and the results were similar to our study with no significant adverse effects noted between the two groups. Peripheral nerve blocks provide intraoperative anaesthesia, extends analgesia in the post-operative period without any systemic side-effects and had advantages over general anaesthesia like avoiding airway instrumentation, polypharmacy, decreased incidence of nausea and vomiting, early mobilization and extended postoperative analgesia.¹⁵

CONCLUSION

Magnesium sulphate with bupivacaine as compared to plain bupivacaine had early onset of sensory block, increase in duration of sensory block, better analgesia without any significant untoward side effect.

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