Background and Objectives The optimal rate of injection of local anesthetic in pediatric caudal blocks has not been determined. The purpose of this study was to determine the influence of two rates of injection on the level of analgesia in children.

Methods The patients, 79 children, American Society of Anesthesiologists class I, who were scheduled for minor surgery, were allocated to three groups according to age: group 1, 0-12 months; group 2, 13-36 months; and group 3, 37-72 months. Each age group was further divided randomly into two subgroups according to rate of injection: subgroup A received 1 mL/kg of 0.25% bupivacaine with 1:200,000 epinephrine at a rate of 1 mL/s, and subgroup B received the same dose at a slower rate of 1 mL per 10 s. Level of analgesia was assessed by loss of sensation to skin pinching. Age, weight, height, time of surgery, onset, and level of analgesia and complications were recorded.

Results For the faster rate, significant differences in level of analgesia were found between groups 1 and 2; the groups were not significantly different for the slower rate, however. The median level in patients 12 months and under was two dermatomes above that of patients older than 12 months at both rates. The levels for each rate (subgroups A and B) were not significantly different in any age group. The time needed to reach the highest level became progressively longer with age (from group 1 to 3), and differences were significant at both rates.

Conclusions Level of analgesia is not affected by the rate injection of 0.25% bupivacaine into the epidural caudal space in children. The time needed to reach the highest level increases as the child ages.