Effectiveness of dexamethasone as an adjuvant to intrathecal bupivacaine versus bupivacaine alone in spinal anesthesia among orthopedic surgery patients at KCMC referral hospital, northern Tanzania

Background: Orthopedic surgeries are associated with significant intraoperative and postoperative pain, necessitating effective anesthesia strategies. Spinal anesthesia is commonly used for lower limb procedures due to its rapid onset and reliability; however, its limited duration may compromise prolonged surgical procedures and early postoperative pain control. Adjuvants such as dexamethasone have been explored to enhance and prolong the effects of local anesthetics. While evidence supports its efficacy, data from low-resource settings remain limited. Objective: To assess the effect of intrathecal dexamethasone as an adjuvant to bupivacaine on sensory block duration, time to first postoperative analgesia, and postoperative pain in patients undergoing lower limb orthopedic surgery at KCMC. Methodology: A randomized, double-blind controlled trial was conducted among 96 adult patients undergoing elective lower limb orthopedic surgery under spinal anesthesia. Participants were allocated using a computer-generated randomization sequence to receive either bupivacaine 15 mg with dexamethasone 4 mg (intervention group) or bupivacaine 15 mg with 1 ml normal saline (control group). Outcomes included sensory and motor block duration, time to first postoperative analgesia, and postoperative pain scores. Results: The dexamethasone group demonstrated a significantly prolonged sensory block duration (231 +/- 6 vs. 156 +/- 9 minutes; mean difference 75.11 minutes, 95% CI: 71.92-78.29; p < 0.001) and delayed time to first postoperative analgesia (252 +/- 7 vs. 181 +/- 7 minutes; mean difference 71.89 minutes, 95% CI: 68.91-74.86; p < 0.001). Motor block duration was also significantly longer (184 +/- 7 vs. 130 +/- 5 minutes; mean difference 53.42 minutes, 95% CI: 50.99-55.85; p < 0.001). Postoperative pain scores were significantly lower at 1 hour (mean difference -1.29 points, 95% CI: -1.52 to -1.05; p < 0.001) and at 2 hours (mean difference -1.97 points, 95% CI: -2.21 to -1.73; p < 0.001). Intraoperative opioid and benzodiazepine use were significantly reduced in the intervention group. Conclusion: The addition of intrathecal dexamethasone to bupivacaine significantly enhances sensory block duration, delays postoperative analgesia need, and improves early pain control. These findings support its use as a potentially practical adjuvant in resource-limited settings.