Transversus abdominis plane block with different bupivacaine concentrations in children undergoing unilateral inguinal hernia repair: a single-blind randomized clinical trial

Background: Current knowledge on the ideal local anesthetic concentration for the ultrasound-guided transversus abdominis plane block (TAPB) in pediatrics is scarce. The purpose of this study is to compare the efficacy of US-guided TAPB at two different concentrations of bupivacaine in pediatrics undergoing unilateral inguinal hernia repair. Methods: After random allocation, 74 children aged 1–8 were randomized to receive US-guided TAPB by using 1 mg.kg^{− 1} bupivacaine as either 0,25% (0,4 ml.kg^{− 1}) (Group 1) or 0,125% (0,8 ml.kg^{− 1}) (Group 2) concentration. All blocks were performed under general anesthesia, immediately after the induction, unilaterally with a lateral approach. All subjects received intravenous 15 mg/kg paracetamol 0.15 mg/kg dexamethasone and 0.1 mg/kg ondansetron intraoperatively. The primary outcome was the efficacy which is assessed by postoperative FLACC behavioral pain assessment score at 15′, 30′, 45′, 1 h, 2 h, 6 h, and 24 h. The secondary outcomes were to assess the total dose of rescue analgesic consumption, length of hospital stay, the incidence of side effects, complications and satisfaction levels of the patients’ parents and the surgeons. Results: Sixty-four children were recruited for the study. Postoperative pain scores were equal between the two groups. There was no need for a rescue analgesic in any group after the postoperative 6^thhour. No local or systemic complication or side effect related to anesthesia or surgery was reported. Conclusion: TAPB using 1 mg.kg^{− 1} bupivacaine administered as either high volume/low concentration or low volume/high concentration was providing both adequate analgesia and no side effects. Trial registration: This trial was retrospectively registered at Clinicaltrals.gov, NCT04202367.