A Comparison Between Dexamethasone and Clonidine as Adjuvants to Levobupivacaine in the Supraclavicular Approach to the Brachial Plexus Block: A Double-Blind Study.

Objective:  The objective of this clinical study is to compare the efficacy of adding dexamethasone or clonidine as an adjuvant drug to levobupivacaine in supraclavicular brachial plexus block (BPB) with regard to the onset and duration of sensory and motor blocks along with duration of postoperative analgesia.

Background:  Brachial plexus block (BPB), with or without general anesthesia, has been used widely for multiple upper limb surgical procedures, by virtue of its efficacy in terms of cost-effectiveness, efficiency, safety margins, and good postoperative analgesia. Various adjuvant drugs have been described to potentiate the analgesic effect of local anesthetic agents such as epinephrine, clonidine, dexamethasone, dexmedetomidine, or midazolam.

Materials And Methods: This is a prospective, randomized, double-blind study in which a total of 90 American Society of Anesthesiology (ASA) physical status I and II patients of either sex, aged between 18 and 60 years, were scheduled for elective upper limb surgical procedures under supraclavicular BPB. They were divided into three equivalent randomized groups with 30 patients in each group. The patients were administered either normal saline 2 mL (in group L) or clonidine 0.5 mcg/kg body weight (in group LC) or dexamethasone 8 mg (in group LD) with 30 mL of 0.5% levobupivacaine. The time of onset and duration of sensory and motor blockades along with the time duration of analgesia were compared.

Results: All groups were equivalent as per demographic data. The time duration for onset of sensory and motor blocks was comparable among all three included groups (12.77±2.60 minutes and 20.80±3.25 minutes, 15.93±2.08 minutes and 22.43±3.07 minutes, and 12.57±2.62 minutes and 22.47±3.10 minutes for group L, LC, and LD, respectively). The time duration of analgesia and motor blockade was significantly prolonged in the dexamethasone group (1195.33±50.01 minutes and 1173.17±43.57 minutes) and moderately prolonged in the clonidine group (696.33±36.74 minutes and 674.67±34.33 minutes) when compared to levobupivacaine group (416.33±35.98 minutes and 397.00±35.12 minutes), and the difference was statistically significant (p<0.001).

Conclusion:  Dexamethasone appears to be a superior adjuvant drug to clonidine for brachial plexus block via supraclavicular approach as it provides prolonged duration of motor block with lesser requirement of postoperative analgesia and lack of adverse effects.