The Dose-Response Relationship for Clonidine Added to a Postoperative Continuous Epidural Infusion of Ropivacaine in Children

Epidurally administered clonidine enhances the quality and duration of postoperative analgesia when it is used as an adjunct to local anesthetics in children. We investigated the dose-response relationship for epidural clonidine when added to a continuous postoperative epidural infusion of ropivacaine. By use of an observer-blinded design, 55 pediatric patients (1–4 yr old) were randomly given a postoperative epidural infusion of plain ropivacaine 0.1% 0.2 mg · kg−1 · h−1 (Group R), ropivacaine 0.08% 0.16 mg · kg−1 · h−1 plus clonidine 0.04 μg · kg−1 · h−1 (Group RC1), ropivacaine 0.08% 0.16 mg · kg−1 · h−1 plus clonidine 0.08 μg · kg−1 · h−1 (Group RC2), or ropivacaine 0.08% 0.16 mg · kg−1 · h−1 plus clonidine 0.12 μg · kg−1 · h−1 (Group RC3). A clear dose-response relationship could be identified for a continuous infusion of epidural clonidine, with clonidine dosages in the 0.08–0.12 μg · kg−1 · h−1 range providing improved postoperative analgesia (reduced Children’s Hospital of Eastern Ontario pain score, increased time to first supplemental analgesic demand, and a reduced total number of doses of supplemental analgesics during the first 48 h after surgery). Analgesia was improved without any signs of increased sedation or other side effects. The adjunct use of epidural clonidine in the dosage range of 0.08–0.12 μg · kg−1 · h−1 appears effective and safe for use in children.