RESUMO
BACKGROUND: This study compares dexmedetomidine and buprenorphine as potential adjuvants for spinal anesthesia. Dexmedetomidine enhances sensory block and minimizes the need for pain medication, while buprenorphine, a long-acting opioid, exhibits a favorable safety profile compared to traditional opioids. METHODS: PubMed, Cochrane and EMBASE were systematically searched in December 2023. ELIGIBILITY CRITERIA: RCTs with patients scheduled for lower abdominal, pelvic, or lower limb surgeries; undergoing spinal anesthesia with a local anesthetic and buprenorphine or dexmedetomidine. RESULTS: Eight RCTs involving 604 patients were included. Compared with dexmedetomidine, buprenorphine significantly reduced time for sensory regression to S1 (Risk Ratio [RR = -131.28]; 95% CI -187.47 to -75.08; I2 = 99%) and motor block duration (RR = -118.58; 95% CI -170.08 to -67.09; I2 = 99%). Moreover, buprenorphine increased the onset time of sensory block (RR = 0.42; 95% CI 0.03 to 0.81; I2 = 93%) and increased the incidence of postoperative nausea and vomiting (RR = 4.06; 95% CI 1.80 to 9.18; I² = 0%). No significant differences were observed in the duration of analgesia, onset time of motor block, time to achieve the highest sensory level, shivering, hypotension, or bradycardia. CONCLUSIONS: The intrathecal administration of buprenorphine, when compared to dexmedetomidine, is linked to reduction in the duration of both sensory and motor blocks following spinal anesthesia. Conversely, buprenorphine was associated with an increased risk of postoperative nausea and vomiting and a longer onset time of sensory block. Further high-quality RCTs are essential for a comprehensive understanding of buprenorphine's effects compared with dexmedetomidine in spinal anesthesia.