Comparative Study of Epidural Dexmedetomidine and Magnesium Sulphate used as Adjuvant to Ropivacaine for Post-Operative Analgesia in Thoracotomy

Background: Dexmedetomidine is the selective 2-adrenoceptor agonist with analgesic potency. Magnesium has antinociceptive effects in animal and human models of pain. Our hypothesis was that the addition of magnesium and dexmedetomidine to thoracic epidural bolus of ropivacaine may increases the duration of analgesia. Methods: Sixty patients undergoing thoracotomy were enrolled to receive either dexmedetomidine(Group D) or magnesium sulphate (Group M) till first epidural top up. In Group D, patients received 1 µg/kg dexmedetomidine +ropivacaine 0.375% and group M patients received magnesium sulphate 75 mg +ropivacaine 0.375% epidurally as an initial bolus dose. Pain assessment using a visual analogue scale (VAS), Time to reach maximum sensory block level, Sensory block level, first epidural top, heart rate, blood pressure sedation scores were observed in the postoperative period. In post – operative monitoring, any untoward complications like hypotension, hypertension, bradycardia, tachycardia, nausea, vomiting, respiratory depression were also observed. Results: The demographic profile of patients was comparable in both the groups. Time to reach maximum sensory block level in group D vs M (16.30±4.27 vs. 14.28 ±3.38) was significantly earlier in the M group. Postoperative analgesia was prolonged significantly in the D group (8.00±1.01 ) as compare to group M (5.27±0.69). Sedation scores were noted <3 in the group D. While the incidence of dry mouth, decrease heart rate significantly were higher in the D group. Incidence of nausea and vomiting, respiratory depression were similar in both group.