Analgesic efficacy of ultrasound-guided transversus abdominis plane block in patients undergoing open appendicectomy

Transversus abdominis plane (TAP) block is a new regional anaesthetic technique that blocks abdominal neural afferents by introducing local anaesthetic into the neuro-fascial plane between the internal oblique and the transversus abdominis muscles. We evaluated its analgesic efficacy in patients undergoing open appendicectomy in a randomized controlled double-blinded clinical trial.

Fifty-two adult patients undergoing open appendicectomy were randomized to undergo standard care (n=26) or to undergo a right-sided TAP block with bupivacaine (n=26). In addition, all patients received patient-controlled i.v. morphine analgesia, regular acetaminophen, and non-steroidal anti-inflammatory drug, as required, in the postoperative period. All patients received standard anaesthetic, and after induction of anaesthesia, the TAP group received an ultrasound-guided unilateral TAP block. Each patient was assessed after operation by a blinded investigator at 30 min and 24 h after surgery.

Ultrasound-guided TAP block significantly reduced postoperative morphine consumption in the first 24 h [mean (sd) 28 (18) vs 50 (19) mg, P<0.002]. Postoperative visual analogue scale pain scores were also reduced in the TAP block group soon after surgery [median (IQR) 4.5 (3-5.3) vs 8.5 (7.5-10), P<0.001] and at 24 h [5.2 (4-6.2) vs 8 (7-8.5), P<0.001]. There were no complications attributable to the TAP block.

Ultrasound-guided TAP block holds considerable promise as a part of a balanced postoperative analgesic regimen for patients undergoing open appendicectomy.