Effect of addition of buprenorphine or dexamethasone to levobupivacaine on postoperative analgesia in ultrasound guided transversus abdominis plane block in patients undergoing unilateral inguinal hernia repair: a prospective randomized double blind controlled trial

BACKGROUND: The transversus abdominis plane (TAP) block is an effective technique to block the thoracolumbar nerves innervating the anterolateral abdominal wall. This study was conducted to evaluate the analgesic efficacy and opioid consumption with the use of perineural buprenorphine or dexamethasone in TAP blocks after unilateral inguinal hernioplasties. METHODS: This prospective, randomized, double-blinded, placebo-controlled study enrolled 93 patients scheduled for unilateral inguinal hernioplasty, followed by an ultrasound-guided TAP block. The participants were randomized into 3 groups (31 patients each). Group L received 20 ml 0.25% levobupivacaine + 1 ml normal saline (NS); group LB, 20 ml 0.25% levobupivacaine + 0.3 mg (1 ml) buprenorphine; and group LD, 20 ml 0.25% levobupivacaine + 4 mg (1 ml) dexamethasone. The patients were observed postoperatively for 24 h for first rescue analgesic requirement, total rescue analgesic consumption, and pain scores on the numeric rating scale (NRS). RESULTS: The time to first rescue analgesic requirement was significantly longer in Group LB than in groups LD and L (688.87 ± 36.11 min, 601.45 ± 39.85 min, and 383.06 ± 36.21 min, respectively; P < 0.001). The mean total tramadol consumption in the first 24 h was the lowest in group LB (P < 0.001, L vs. LB / LD). Groups LB and LD displayed significantly lower NRS scores than group L (P < 0.001 both). CONCLUSIONS: Levobupivacaine with perineural buprenorphine in a TAP block after unilateral open inguinal hernioplasty facilitates prolonged analgesia and reduced requirement for rescue analgesics compared to perineural dexamethasone, without significant side effects.