The addition of clonidine 2 microg.kg-1 does not enhance the postoperative analgesia of a caudal block using 0.125% bupivacaine and epinephrine 1:200,000 in children: a prospective, double-blind, randomized study

BACKGROUND: In this prospective, randomized, double-blind study, we compared the efficacy of 0.125% bupivacaine and epinephrine 1:200,000 with and without clonidine 2 microg.kg-1 for 'single shot' pediatric caudal analgesia. METHODS: Thirty ASA I and II children, ages 2-8 years, undergoing outpatient surgical procedures below the umbilicus received 1 ml.kg-1 0.125% bupivacaine with fresh epinephrine 1:200,000 and clonidine 2 microg.kg-1 (group-C) or 1 ml.kg-1 0.125 % bupivacaine with epinephrine 1:200 000 (group-NC). All patients received a standardized general anesthetic (induction with 67% N2O in O2 and sevoflurane followed by isoflurane maintenance). Primary outcome measures were time to first rescue analgesic and number of patients requiring rescue analgesic at 4, 6, 8, 12, and 24 h after caudal placement. Secondary outcome measures included: extubation times, Objective Pain Scale (OPS) scores, sedation scores, time in postanesthesia care unit (PACU), discharge time, number of analgesic doses given in 24 h following caudal blockade, and adverse effects (vomiting, hypotension, and bradycardia). RESULTS: There were no differences in demographics, investigated parameters, or adverse effects between groups. CONCLUSIONS: We found that the addition of clonidine 2 microg.kg-1 to 0.125% bupivacaine with fresh epinephrine 1:200,000 for caudal analgesia did not significantly delay the time to first rescue analgesic or decrease the overall need for rescue analgesics in children 2-8 years undergoing surgical procedures below the umbilicus.