Ultrasound-guided tranversus abdominis plane block for herniorrhaphy in children

Abstract

Regional anaesthesic techniques are commonly used for the management of pain following lower abdominal surgery in children. The transversus abdominis plane (TAP) block has shown promise for perioperative analgesia, but data on the optimal dose regimen are limited. To evaluate the optimal dose of levobupivacaine for successful ultrasound-guided TAP block in children. A dose finding prospective study using Dixon's up-and-down sequential method. University Hospital Paediatric Anaesthesia Unit. Twenty-seven consecutive children aged 1 to 5 years scheduled for day-case elective herniorrhaphy. After standardised induction of general anaesthesia, ultrasound-guided TAP block was performed with a fixed volume of 0.2 ml kg(-1) of levobupivacaine solution. The dose of levobupivacaine was determined by Dixon's up-and-down method starting from 0.5 mg kg(-1)with an interval of 0.1 mg kg(-1). Block failure was defined as a 20% increase in heart rate or mean arterial pressure from baseline. Rescue analgesia consisted of intravenous remifentanil infusion during surgery and intravenous nalbuphine in the postanaesthetic care unit (PACU). Patients were assessed using the FLACC (face, legs, activity, cry and consolability) pain scale, the rescue analgesic consumption in the PACU and day-case unit and the postoperative pain measure for parents score at home. The mean effective dose of levobupivacaine resulting in an effective TAP block in 50% of cases (ED50) obtained by using Dixon's up-and-down sequential method. The ED50 and ED95 were further estimated by bootstrapping. The ED50 according to the up-and-down staircase method was 0.22 mg kg(-1) [95% confidence interval (CI) 0.19 to 0.25]. Bootstrap replicates of the original dataset resulted in ED50 and ED95 estimates of 0.16 mg kg(-1) (95% CI 0.11 to 0.24) and 0.43 mg kg(-1)(95% CI 0.30 to 0.57), respectively. As part of a multimodal analgesia strategy, ultrasound-guided TAP block with 0.2 ml kg(-1)of 0.2% levobupivacaine provides successful peroperative analgesia in 95% of children who underwent herniorrhaphy.