Paravertebral block with morphine or dexmedetomidine as adjuvant to bupivacaine for post-operative analgesia in modified radical mastectomy: A prospective, randomised, double-blind study

BACKGROUND AND AIMS: General anaesthesia (GA) is the standard technique and paravertebral block (PVB) is suggested as an ideal analgesic in patients undergoing modified radical mastectomy (MRM). This study assessed post-operative analgesic efficacy of morphine or dexmedetomidine as adjuvant to bupivacaine in PVB. METHODS: Forty-five women (18–60 years) undergoing MRM ± axillary clearance received PVB with 20 ml bupivacaine 0.25% with morphine 3 mg (Group BM) or dexmedetomidine 1 μg/kg (Group BD) in this prospective, randomised, double-blind study. After confirming the onset of PVB, standardised GA induction sequence was used. Intra-operative consumption of fentanyl and propofol along with postoperative morphine and diclofenac consumption, numerical rating scores (NRS) for pain at rest and on movement, nausea and vomiting scores, sedation scores and time to rescue analgesic were recorded. Chi-square or Fisher's exact test and Kruskal–Wallis followed by Mann–Whitney U-test were applied as applicable. RESULTS: The number of patients requiring morphine during first 2-h post-operatively was significantly lower (P = 0.006) in Group BM. The mean dose of morphine in Group BM (0.84 [2.41] mg) and Group BD (1.70 [1.84] mg) was comparable (P = 0.187). NRS for pain at rest and on movement was significantly lower in Group BM at 2, 6, 12 and 18 h. The duration of analgesia was significantly prolonged in Group BM (1019.8 [422.9] min) than in Group BD (263.7 [194.9] min) (P < 0.001). CONCLUSION: Morphine is superior adjuvant to bupivacaine in PVB for modified radical mastectomy than dexmedetomidine.