Comparison of a bupivacaine-clonidine mixture with plain bupivacaine for caudal analgesia in children.

In a randomized, double-blind study in children undergoing elective orthopaedic surgery, we have assessed the clinical value of combining clonidine with bupivacaine for caudal analgesia. Forty-six children, aged 1-10 yr, were allocated randomly to two equal groups to receive 0.25% bupivacaine 1 ml kg-1 combined with either normal saline 1 ml (group A) or clonidine 2 micrograms kg-1 in normal saline 1 ml (group B). Mean (SD) duration of caudal analgesia for groups A and B were 5.2 (1.2) h and 9.8 (2.1) h, respectively (P < 0.0001). Group B required significantly less supplementary analgesia after operation (P < 0.01). There was no significant difference in the incidence of side effects between the two groups. The longer duration of sedation in group B (9.1 (2.5) h) resulted partly from the sedative effect of clonidine and partly from the longer duration of analgesia provided by clonidine. We conclude that, when added to bupivacaine, clonidine improves the efficacy of caudal analgesia in children.