Postoperative Analgesic Efficacy of Nalbuphine vs Dexmedetomidine as Adjuvants to Ropivacaine in Ultrasound Guided Transversus Abdominis Plane Block for Abdominal Hysterectomies: A Randomised Clinical Study

Introduction: Transversus Abdominis Plane (TAP) block has been practised as an effective alternative to systemic analgesics to achieve adequate postoperative analgesia, with minimal systemic side effects. Dexmedetomidine, an alpha-2 agonist and nalbuphine, an opioid, have been studied as adjuvants to local anaesthetics to improve the analgesic profile of regional anaesthetic blocks. Aim: To compare the duration and quality of postoperative analgesia of dexmedetomidine and nalbuphine when used as adjuvants to ropivacaine for TAP block. Materials and Methods: This was a randomised double blinded study conducted on 60 patients undergoing total abdominal hysterectomies under spinal anaesthesia. Patients were randomly distributed into two groups of 30 patients each, to receive either 39 mL of 0.2% ropivacaine+50 mu g dexmedetomidine (1 mL) (group D) or 39 mL of 0.2% ropivacaine+10 mg nalbuphine (1 mL) (group N), for bilateral TAP block. Postoperative pain scores, time for first rescue analgesic request and incidence of side effects were compared. Results: Duration of postoperative analgesia was similar in both groups (409.14 +/- 48.92 minutes in group D vs 419.03 +/- 54.11 minutes in group N) (p-value=0.462). Postoperative pain scores and total amount of rescue analgesic requirement (105.17 +/- 42.98 vs 106.45 +/- 46.08) was also similar in both the groups (p=0.912). In Nalbuphine group, 16.7% reported pruritis (p-value=0.02) and 13.3% reported nausea (p-value=0.213). However, in group D only one patient reported nausea two hours postoperatively. Conclusion: Nalbuphine when compared to dexmedetomidine, as an additive to ropivacaine for TAP block, provides similar postoperative analgesic duration and efficacy, but increases the incidence of pruritus and nausea.