Postoperative Analgesic Effect of Morphine Added to Bupivacaine for Transversus Abdominis Plane (TAP) Block in Appendectomy.

Background Transversus abdominis plane (TAP) block with local anaesthetics produces effective pain relief following lower abdominal surgeries. Although opioids have been found to have effects through peripheral receptors also, reports on their effect when used as additive to local anaesthetics for TAP block are lacking. Objective To assess the analgesic effect of peripherally administered morphine with bupivacaine for ipsilateral TAP block in patients undergoing emergency appendectomy under general anaesthesia. Method Sixty patients undergoing appendectomy were randomized to undergo ipsilateral TAP with 20 ml of 0.5% bupivacaine plus 2 ml of NS (total 22 ml) and 2 ml of intravenous (IV) saline (Group TB) or with 20ml of 0.5% bupivacaine plus 2 mg (2 ml) of morphine (total 22 ml) and 2 ml of NS IV (Group TBM) or with 20 ml of 0.5% bupivacaine plus 2 ml of NS (total 22 ml) and 2 mg (2 ml) IV morphine (Group TB-IVM). Pain severity was measured using Visual Analogue Scale (VAS) preoperatively (Baseline) and at 30 min, 6h, 12 h and 24 h postoperatively. Inj. tramadol 50 mg IV was used as rescue analgesic when postoperative VAS was 4 or more. The duration of analgesia (time to first analgesic) and the postoperative 24 h tramadol requirement was recorded. Result The mean duration of analgesia in Group TBM was significantly longer (801.50 ± 74.92 min, p=0.002) than in Group TB (720.00 ± 42.17 min) and Group TB-IVM (712.70 ± 40.94 min). The mean postoperative 24 h tramadol requirement was also less in Group TBM (69.23 ± 25.31mg) than in Groups TB (100.00 ± 38.34 mg) and TB-IVM (95.00 ± 39.40 mg) but did not reach the level of statistical significance (p=0.057). Significantly less ondansetron was required in Group TBM (3.80 ± 2.04 mg) than in Group TB (6.80 ± 2.93 mg) and TB-IVM (6.00 ± 2.75 mg) (p=0.002). Conclusion Morphine added to bupivacaine effectively prolongs the analgesic duration of TAP block in appendectomy.