Comparative study of intrathecal midazolam versus fentanyl as adjuvants to ropivacaine for lower-limb surgery

Background The current prospective randomized double-blind study was designed to compare the clinical efficacy of intrathecal midazolam versus fentanyl when added to hyperbaric ropivacaine, evaluating the effect of each on the duration and quality of spinal blockade produced by hyperbaric ropivacaine. Patients and methods The study was conducted on 90 patients of both sexes, aged 20-60 years, of class I or II of the American Society of Anesthesiologists classification, who were undergoing elective lower-limb surgery. Patients were randomly assigned to three groups (30 patients each): group R (control group) received 3 ml (15 mg) of hyperbaric ropivacaine plus 0.5 ml of normal saline (0.9%) at a total volume of 3.5 ml intrathecally, whereas group RF received 3 ml (15 mg) of hyperbaric ropivacaine plus 0.5 ml of 25 μg fentanyl (50 μg/ml) at a total volume of 3.5 ml intrathecally and group RM received 3 ml (15 mg) of hyperbaric ropivacaine plus 0.5 ml of 1 mg midazolam (2 mg/ml) at a total volume of 3.5 ml intrathecally. The onset and duration of sensory and motor blockade, postoperative pain, and the time to first rescue analgesia request were noted. Patients were observed for hypotension, bradycardia, sedation, respiratory depression, pruritus, and postoperative nausea and vomiting. Results The onset times and the duration of motor blockade were comparable among groups, whereas the time to sensory block regression was longer in group RM and group RF as compared with group R (P < 0.001). The duration of postoperative analgesia was significantly longer in group RM and group RF as compared with group R (P < 0.001), whereas there was no difference between group RM and group RF. The incidence of pruritus and vomiting was higher in group RF. Conclusion Adding midazolam to hyperbaric ropivacaine in spinal anesthesia for lower-limb surgeries is considered a good alternative for improving the duration of sensory block and decreasing the analgesic requirement in the early postoperative period with minimal side effects compared with hyperbaric ropivacaine alone or fentanyl combined with hyperbaric ropivacaine.