Comparison of the Effects of Dexamethasone and Magnesium Sulfate Used as Adjuvants on Infraclavicular Brachial Plexus Nerve Block: A Prospective, Double-Blinded Randomized Controlled Trial

TL;DR

This study compares dexamethasone and magnesium sulfate as additives to a nerve block anesthetic, finding that dexamethasone improves block duration and reduces pain medication use.

Contribution

The study provides new evidence that dexamethasone is more effective than magnesium sulfate as an adjuvant in brachial plexus nerve blocks.

Findings

Dexamethasone significantly prolonged motor and sensory block durations compared to magnesium sulfate and saline.

Dexamethasone reduced postoperative opioid and NSAID consumption and improved pain scores at 12 and 24 hours.

Dexamethasone shortened the onset times of motor and sensory blocks compared to the other groups.

Abstract

Background

This prospective clinical study aims to compare the effectiveness of lower-dose dexamethasone and magnesium sulfate as adjuvants to bupivacaine in ultrasound-guided infraclavicular brachial plexus block for distal upper limb surgery.

Materials and methods

Ninety patients, aged 18 to 65 years, with American Society of Anesthesiologists (ASA) physical status scores of I or II who underwent distal upper limb surgeries, including the arm, elbow, forearm, and hand surgery under infraclavicular brachial plexus block, were included in the study. The block was performed under ultrasound guidance. Patients were allocated to three groups: Group B received 20 mL of 0.5% bupivacaine combined with 5 mL of 0.9% NaCl; Group B+D received 20 mL of 0.5% bupivacaine combined with 4 mg of dexamethasone and 4 mL of 0.9% NaCl; and Group B+M received 20 mL of 0.5% bupivacaine combined with 150 mg of magnesium sulfate and 4 mL of 0.9% NaCl. Outcomes assessed included sensory and motor block onset times, durations of sensory and motor blocks, duration of analgesia, perioperative hemodynamic parameters, and opioid and non-steroidal anti-inflammatory drug (NSAID) consumption.

Results

Data from 90 patients were analyzed. Demographic characteristics and ASA scores were comparable across groups (p > 0.05). Group B+D demonstrated significantly longer durations of motor block, sensory block, and analgesia compared to Group B and Group B+M (p = 0.001). Moreover, Group B+D showed significantly shorter motor (p = 0.001) and sensory (p = 0.003) block onset times and reduced postoperative opioid and NSAID analgesic consumption, as well as lower VAS scores at 12 and 24 hours postoperatively (p = 0.001).

Conclusion

When added as an adjuvant to bupivacaine, dexamethasone resulted in longer durations of motor and sensory block, shorter onset times for both motor and sensory block, and better postoperative analgesia compared to magnesium sulfate. It also reduced opioid and NSAID consumption during the first 24 hours.

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