Comparison of caudal bupivacaine alone with bupivacaine plus two doses of dexmedetomidine for postoperative analgesia in pediatric patients undergoing infra-umbilical surgery: a randomized controlled double-blinded study.

Background: Data are still insufficient about the effects of different concentrations of caudal dexmedetomidine when used to prolong postoperative analgesia in children. The aim of this study was to assess the analgesic efficacy and side effects of two doses of caudal dexmedetomidine (1 and 2 μg·kg(-1)) co-administered with bupivacaine in terms of postoperative pain scores and requirement of postoperative analgesia over 24 h in children undergoing infra-umbilical surgery.

Methods: Ninety-one children, aged 1-6 years, undergoing infra-umbilical surgery were included and randomly allocated into three groups of caudal block. Group B received 0.25% bupivacaine 2 mg·kg(-1) (0.8 ml·kg(-1)). Groups BD1 and BD2 received dexmedetomidine 1 and 2 μg·kg(-1), respectively along with bupivacaine 2 mg·kg(-1) in a total volume of 0.8 ml·kg(-1). Anesthesia was induced and maintained with sevoflurane in 100% oxygen. Hemodynamic and other routine intraoperative monitoring was carried out in addition to endtidal sevoflurane concentration. Time to spontaneous eye opening and postoperative pain and sedation scores were recorded in addition to time to first analgesia, paracetamol analgesic requirements, and any side effects during the first 24 postoperative hours.

Results: Time to first analgesia requirement was significantly longer in BD1 and BD2 groups compared to B group with mean values (95% CI) of 809 min (652-965), 880 (733-1026), and 396 (343-448), respectively, P < 0.001. Postoperative paracetamol analgesic requirements over 24 h were higher in group B compared to BD1 and BD2 groups (Mean (95% CI): 3.2 (2.9-3.5) doses, 1.9 (1.5-2.3), and 1.6 (1.3-1.9), respectively), P < 0.001. The dexmedetomidine groups had significantly higher postoperative sedation scores compared to plain bupivacaine group that were dose dependent and for longer time in BD2 group. Two patients in BD2 group developed bradycardia and hypotension, and one developed urine retention compared to none in other groups.

Conclusion: A 1 μg·kg(-1) dose of caudal dexmedetomidine achieved comparable prolongation of postoperative analgesia to 2 μg·kg(-1) dose, with shorter duration of postoperative sedation and lower incidence of other side effects.