Background: Different adjuvants have been used to extend spinal anesthesia, with the probable benefits of late commencement of postoperative pain and reduced analgesic requirements. Alpha-2 adrenoceptor agonists have been recently used for their sedative, analgesic, and perioperative sympatholytic and cardiovascular stabilizing effects with reduced anesthetic requirements.
Objective: In this prospective, randomized, double-blind study, we evaluated the intravenous dexmedetomidine and compared it with intravenous midazolam for effect on sensory and motor blockade, sedation, hemodynamic parameters, duration of analgesia, and side effects during spinal anesthesia.
Materials and Methods: A total of 60 patients scheduled for lower abdominal and lower limb surgery were selected. Group D (n = 30) received dexmedetomidine (1 μg/kg) over 10 min before spinal anesthesia, followed by infusion of 0.5 µg/kg/h during surgery. Group M (n = 30) received midazolam (0.04 mg/kg) over 10 min before spinal anesthesia, followed by infusion of 0.04 mg/kg/h during surgery. Time for onset of sensory and motor blockade, sedation score using Ramsay Sedation Score (RSS), hemodynamic parameters, and duration of analgesia were assessed.
Result: The mean time to achieve the highest sensory level and onset of grade 3 motor block were comparable in both the groups (p > 0.05). The mean time to complete regression of sensory analgesia (261.17 ± 23.81 vs. 234.83 ± 22.61 min; p < 0.001) and duration of motor block (232.17 ± 27.94 vs. 199.67 ± 22.36 min; p < 0.001) were significantly longer in group D when compared with group M. The total duration of analgesia (356.67 ± 54.56 vs. 260.33 ± 18.84 min) was significantly longer in group D when compared with group M (p < 0.001).The mean time to achieve RSS of three was significantly shorter in group D when compared with group M (p < 0.05). Statistically significant decrease in heart rate was observed in group D when compared with group M.
Conclusion: When compared with intravenous (IV) midazolam, administration of IV dexmedetomidine during spinal anesthesia prolongs the duration of sensory and motor blockade and provides a longer duration of postoperative analgesia, with satisfactory arousable sedation and minimal side effects.
Key words: Dexmedetomidine, midazolam, comparison, spinal anesthesia
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