Ultrasound-Guided Caudal Epidural Block Using Dexmedetomidine as an Adjuvant to Ropivacaine for Paediatric Infraumbilical Surgery: A Randomised, Double-Blind, Controlled Trial

Abstract

Background: A single caudal injection of local anaesthetic is a dependable way to cover infraumbilical surgery in young children, but its analgesia fades within a few hours. We asked whether a low, 1 µg/kg dose of dexmedetomidine, mixed with 0.25% ropivacaine and delivered under real-time ultrasound, would meaningfully lengthen that window without disturbing the circulation. Methods: Sixty children aged 1–6 years (ASA I–II) scheduled for elective infraumbilical procedures were allocated, 30 per arm, to Group D (ropivacaine 0.25% 1 mL/kg plus dexmedetomidine 1 µg/kg in 1 mL saline) or Group N (ropivacaine 0.25% 1 mL/kg plus 1 mL saline). Each block was placed under general anaesthesia with ultrasound guidance. The primary endpoint was the interval to a FLACC score ≥ 4; heart rate, mean arterial pressure, oxygen saturation, Ramsay sedation, rescue-analgesic dosing and adverse events were followed for 24 hours. Results: Analgesia persisted for 598 ± 81 minutes in Group D against 380 ± 81 minutes in Group N (p < 0.001) — a gain of roughly 3.6 hours. Most children given dexmedetomidine (26 of 30) needed only one rescue dose over 24 hours, whereas 17 of 30 controls needed three (p < 0.001). Pulse rate, mean arterial pressure, oxygen saturation and sedation scores overlapped between arms at every time point. Neither group recorded hypotension, bradycardia, vomiting or respiratory depression. Conclusion: Adding 1 µg/kg dexmedetomidine to caudal ropivacaine lengthened postoperative pain relief by about 57% — roughly 3.6 hours — and cut rescue-analgesic demand, while leaving haemodynamics and safety unchanged. Clinical Trial Registration Number: REF/2026/09/140236