Clonidine, but not dexamethasone, prolongs ropivacaine-induced supraclavicular brachial plexus nerve block duration

Background: Ultrasound-guided supraclavicular brachial plexus block (USSB) provides excellent postoperative analgesia after upper extremity surgery. Dexamethasone and clonidine have been added to local anesthetics to enhance and prolong the duration of analgesia. Objective: The objective of this randomized prospective study is to evaluate the efficacy of dexamethasone, clonidine, or combination of both as adjuvants to ropivacaine on the duration of USSB for postoperative analgesia. Methods: Patients receiving USSB for postoperative pain control for upper extremity surgery were randomized to one of four groups; ropivacaine 0.5%, ropivacaine 0.5% with 4 mg dexamethasone, ropivacaine 0.5% with 100 mcg clonidine, or ropivacaine 0.5% with 4 mg dexamethasone and 100 mcg clonidine. Pain scores, sensory and motor function were evaluated at post anesthesia care unit (PACU), discharge and at 24 h postoperatively. Results: The duration of sensory and motor blocks was significantly longer in clonidine groups when compared to ropivacaine alone [Sensorial analgesia: ropivacaine alone 13.4±6, Ropivacaine-Clonidine 17.4±6; Ropivacaine-Dexamethasone-Clonidine 18.8±6.2; Motor blocks: Ropivacaine 12±5, Ropivacaine-Clonidine 16.8±5.2, Ropivacaine-Dexamethasone-Clonidine 18.2±5.7]. In clonidine groups, there was significant prolongation of motor and sensory block when compared to ropivacaine group alone. Conclusion: The results demonstrated that clonidine significantly prolongs the duration of ropivacaine effects for the postoperative analgesia in patient underwent upper arm surgeries.