Effect of adding dexamethasone to bupivacaine on transversus abdominis plane block for abdominal hysterectomy: A prospective randomized controlled trial

PURPOSE: Different adjuvants have been used to improve the quality and increase the duration of local anesthetics during various nerve block techniques. The current study was aimed to evaluate the effect of adding dexamethasone to bupivacaine on the quality and duration of transversus abdominis plane (TAP) block. METHODS: Sixty adult patients undergoing elective open abdominal hysterectomy were randomly allocated to receive TAP block using 20 mL of bupivacaine hydrochloride 0.25% + 2 mL saline 0.9% (control group, n=30) or 20 mL of bupivacaine hydrochloride 0.25% + 2 mL dexamethasone “8 mg” (dexamethasone group, n=30). The primary outcome was postoperative pain, as evaluated by visual analog scale (VAS) for pain scoring at 1, 2, 4, 12, 24 and 48 h postoperatively, whereas the secondary outcomes were time to first analgesia (TFA), morphine consumption and the occurrence of nausea, vomiting or somnolence. RESULTS: The pain VAS score was significantly lower at the postoperative 2 h (4.9 vs. 28.1, P=0.01), 4 h (12.2 vs. 31.1, P=0.01) and 12 h (15.7 vs. 25.4, P=0.02). Furthermore, TFA was significantly longer in the dexamethasone group (459.8 vs. 325.4 min, P=0.002), with lesser morphine requirements in the postoperative 48 h (4.9 vs. 21.2 mg, P=0.003) and lower incidence of nausea and vomiting (6 vs. 14, P=0.03). No complications attributed to the block were recorded. CONCLUSION: Addition of dexamethasone to bupivacaine in TAP block prolonged the duration of the block and decreased the incidence of nausea and vomiting.