Dexmedetomidine versus midazolam as adjuvants to intrathecal bupivacaine: A clinical comparison

BACKGROUND AND AIMS: Trials are being carried out to identify an adjuvant to intrathecal bupivacaine that preferably potentiates postoperative analgesia. This prospective, randomized, double-blind study was aimed to compare the onset and duration of sensory and motor block, postoperative analgesia and adverse effects of dexmedetomidine or midazolam given with 0.5% hyperbaric bupivacaine for spinal anesthesia. MATERIAL AND METHODS: A total of 80 patients, scheduled for vaginal hysterectomies, were randomly allocated to Group D (n = 40) to receive intrathecally 3.0 mL 0.5% hyperbaric bupivacaine +5 ug dexmedetomidine in 0.5 mL of normal saline; and Group M (n = 40) to receive 3 mL of 0.5% hyperbaric bupivacaine +2 mg midazolam in 0.4 mL (5 mg/mL) +0.1 mL normal saline. The onset, duration of sensory and motor block, time to first postoperative analgesia and side effects were noted. Power and Sample size (PS) version 3.0.0.34 was used for power and sample size calculation. Statistical analysis was performed using Microsoft (MS) Office Excel software with the Student's t-test and Chi-square test (level of significance P = 0.05). RESULTS: Duration of sensory, motor blockade and time to the first requirement of analgesia were significantly higher in Group D. Postoperative visual analog scale was significantly less in Group D than Group M. Both groups were similar with respect to sedation, hemodynamic variables and side-effects. CONCLUSION: Intrathecal dexmedetomidine was better adjuvant than midazolam as it produces significantly longer duration of sensory block, reduced doses of postoperative analgesic agents with comparable side-effects.