Effect of epidural clonidine on minimum local anesthetic concentration (ED50) of levobupivacaine for caudal block in children.

BACKGROUND

Clonidine has the potential to significantly prolong the duration of caudal epidural anesthesia. We investigated the effect of the addition of clonidine to the MLAC of levobupivacaine in a randomized controlled dose-response trial.

METHODS

A group of 120 children aged <6 years of age received caudal anesthesia with levobupivacaine and 1, 2, or 3 μg·kg(-1) of clonidine. The MLAC was determined according to a Dixon-Massey protocol. The primary outcome was effective surgical anesthesia. Secondary outcomes were the duration of postoperative analgesia, postoperative pain scores, clonidine side effects, and time to hospital discharge.

RESULTS

The MLAC of caudal levobupivacaine was 0.106%, 0.077%, and 0.035% with 1, 2, and 3 μg·kg(-1) of clonidine, respectively. There were significant dose-dependent increases in median duration of analgesia. The incidence of delayed discharge, somnolence, and PONV was significantly increased in the 3 μg·kg(-1) of clonidine group.

CONCLUSIONS

Clonidine produces a local anesthetic sparing effect with a dose-dependent decrease in levobupivacaine MLAC for caudal anesthesia. In addition, there is a dose-dependent prolongation of postoperative analgesia following lower abdominal surgery in children. A dose of 2 μg·kg(-1) of clonidine provides the optimum balance between improved analgesia and minimal side effects.