Two Dosages of Dexamethasone (2 mg and 4 mg) as Analgesic Adjuvant to Levobupivacaine in Ultrasound-guided Brachial Plexus Block in Upper Limb SurgeryA Randomised Clinical Trial

Introduction: Perineural dexamethasone gives promising results in prolonging duration of analgesia in brachial plexus block. Doses between 1 to 10 mg have been used but the optimum dose is not yet settled.

Aim: To compare the analgesic efficacy of two low doses of dexamethasone in Ultrasonography (USG)-guided brachial plexus block for planned upper limb surgery.

Materials and Methods: A double-blind randomised clinical trial was conducted with 126 adult patients of either sex, randomised in equal numbers to 2 mg and 4 mg dexamethasone groups, the steroid being administered in conjunction with 0.5% levobupivacaine. Time to onset of sensory and motor blocks, duration of analgesia, duration of motor block, total consumption of analgesics in the first 24 hours postoperative period, haemodynamic parameters and features of neurotoxicity were compared. Tramadol 50 mg intravenous was permitted as analgesic. Stastistical Package for Social Sciences (SPSS) Version 24.0 was used for data analysis.

Results: No significant differences in onset of sensory and motor blocks were encountered. Duration of sensory block with 4 mg {median (Interquartile range); 1080 (915-1140) min} clearly exceeded that with 2 mg {840 (720-960) min} (p-value <0.001) dexamethasone. Duration of motor block was also greater with 4 mg dexamethasone {1080 (1020-1170) versus 870 (810-990) min} (p-value <0.001). Total analgesic consumption in first 24 hours was 225 (175-250) mg versus 100 (75-200) mg in 2 mg and 4 mg groups respectively (p-value <0.001). No features of neurotoxicity were encountered in either group.

Conclusion: Perineural dexamethasone 4 mg gives better results as analgesic adjuvant to bupivacaine compared to 2 mg in brachial plexus block for upper limb surgery without increasing adverse effects.