Publication:

Dexmedetomidine versus dexamethasone as intrathecal adjuvants for tibiofibular fracture fixation under spinal anaesthesia: a prospective randomised double-blind study

Background Postoperative pain following tibiofibular fracture fixation may outlast the analgesic duration of hyperbaric bupivacaine used for spinal anaesthesia. Intrathecal adjuvants such as dexmedetomidine and dexamethasone have been used to improve block characteristics and prolong postoperative analgesia. To compare the analgesic efficacy and safety of intrathecal dexmedetomidine and dexamethasone as adjuvants to hyperbaric bupivacaine in adults undergoing spinal anaesthesia for tibiofibular fracture fixation.

Methods In this prospective randomised double-blind trial, 68 ASA I–II patients scheduled for unilateral tibiofibular fracture fixation were randomised to receive 15 mg hyperbaric bupivacaine with either 5 μg dexmedetomidine (BDM, n=34) or 4 mg dexamethasone (BDA, n=34). The primary outcome was duration of analgesia, defined as the interval between onset of sensory block and a Numerical Rating Scale pain score >3. Secondary outcomes included onset of sensory and motor block, postoperative pain scores, adverse events, and patient satisfaction.

Results Baseline characteristics were comparable between groups. Compared with dexamethasone, dexmedetomidine produced a faster onset of sensory block (3.0±0.82 vs 3.8±0.9 min; p=0.001) and motor block (4.1±0.9 vs 5.0±1.1 min; p=0.001), and significantly prolonged analgesia (328.6±28.1 vs 263.0±26.1 min; p<0.001). Pain scores at 4 hours were lower and patient satisfaction was higher in the dexmedetomidine group (both p<0.001). However, hypotension occurred more frequently with dexmedetomidine (29.4% vs 2.9%; p=0.003).

Conclusion Intrathecal dexmedetomidine provided superior block characteristics, longer postoperative analgesia, lower pain scores, and greater patient satisfaction than intrathecal dexamethasone, although these benefits were accompanied by an increased incidence of intraoperative hypotension.