Clonidine increases duration of bupivacaine caudal analgesia for ureteroneocystostomy: a double-blind prospective trial.

PURPOSE: We evaluated whether clonidine, when added to bupivacaine, would significantly prolong caudal analgesia and decrease opioid requirements in children undergoing ureteroneocystostomy.

MATERIALS AND METHODS: A total of 35 children 1 to 10 years old undergoing ureteroneocystostomy received a standardized regimen of general anesthesia, and were randomized to receive a preincision caudal block consisting of either 1 ml/kg 0.125% bupivacaine (controls) or 1 ml/kg 0.125% bupivacaine with 1 microg/kg clonidine (treatment group). Caudal solutions also contained 1:400,000 epinephrine. Following the surgical procedure a second caudal block was performed with half of the original dose of medications. Caregivers were blinded to which caudal solution was administered. Postoperative outcome measures included pain scores, morphine requirements, duration of caudal analgesia and sedation scores. Statistical analysis was performed using ANOVA.

RESULTS: The 2 study groups were similar for mean age, weight and length of surgical procedure. Two patients in the control group were excluded because of protocol violation. Intravenous morphine requirements for rescue therapy were 0.02 mg/kg in the postanesthesia care unit and 0.1 mg/kg on postoperative day 1 for the treatment group, compared to 0.05 mg/kg and 0.2 mg/kg, respectively, for controls (p <0.05). Mean interval from anesthesia finish time to first administered dose of morphine was 8.0 hours for the treatment group and 3.9 hours for controls (p = 0.01). Five of 18 patients in the clonidine-bupivacaine group received no postoperative morphine, compared to 1 of 15 in the bupivacaine group. No patient had development of hemodynamic instability, respiratory depression or sedation requiring treatment.

CONCLUSIONS: The addition of clonidine to bupivacaine significantly increases the duration of caudal analgesia and decreases postoperative morphine requirements in children undergoing ureteroneocystostomy.