The analgesic and sedative effects of intrathecal midazolam in perianal surgery

Summary Background and objective: Our purpose was to evaluate the analgesic and sedative effects of intrathecal midazolam when added to spinal bupivacaine in patients undergoing perianal surgery under spinal anaesthesia. Methods: Forty-four patients were randomly allocated into two equal groups: Group I (B) received hyperbaric bupivacaine 0.5% 2 mL + saline 0.9% 1 mL in a total volume of 3 mL intrathecally; Group II (BM) received hyperbaric bupivacaine 0.5% 2 mL + 1 mL of 2 mg preservative-free midazolam in a total volume of 3 mL intrathecally. In both groups, the onset and recovery times of sensory block, the degree and recovery times of motor block as well as the sedation and visual analogue pain scores were recorded, and statistically compared. Results: In Group BM, the postoperative visual analogue pain scores were significantly lower at the first 4 h (P < 0.05), the average time until the first dose of additional analgesic requirement was significantly longer (P < 0.05), and sedation scales were significantly higher (P < 0.05), compared to Group B. There were no statistically significant differences in the onset and the full recovery times of sensory and motor blocks in the two groups. Conclusion: The use of intrathecal midazolam combined with intrathecal bupivacaine produces a more effective and longer analgesia with a mild sedative effect in perianal surgery.