Perineural Dexamethasone, Dexmedetomidine, or Their Combination to Reduces Rebound Pain After Supraclavicular Brachial Plexus Block

Dexmedetomidine, an α2 adrenoceptor agonist, and dexamethasone, a potent anti-inflammatory steroid, are commonly used, effective, and safe adjuvants to peripheral nerve block (PNB). Both have been found to delay and reduce the incidence of rebound pain (RP), prolong the duration of sensory and motor block, and enhance analgesia without causing significant respiratory depression. Few studies have explored the effectiveness of dexmedetomidine or dexamethasone as sole adjuvants to PNB for preventing or reducing RP. However, no study has directly compared the effectiveness of these two drugs in reducing RP when used as adjuvants to local anesthetic (LA) in PNB. Due to differences in their mechanism of action, their effects on RP may differ significantly. The investigators hypothesized that the combination of dexamethasone and dexmedetomidine reduces the incidence of RP when used as adjuvants to LA in PNB.