Effect of Clonidine on Duration of High-Volume, Low-Concentration Caudal Epidurals

Caudal blocks are a common pediatric regional anesthesia technique used to alleviate intra- and postoperative pain following circumcision. The addition of the alpha-2 agonist clonidine has been shown to increase the duration of the block. Another method for prolonging the effect of the block is using a high-volume, low-concentration (HVLC) local anesthetic in the caudal solution. The primary aim of this study was to compare the duration of caudal blockade using HVLC with and without clonidine. The effect of epidural clonidine on postoperative emergence agitation (EA) was assessed as a secondary outcome.  Methodology: This was a prospective, randomized, and observer-blinded study. The participants comprised 129 children, aged 0-3 years, classified as American Society of Anesthesiologists Physical Status Class 1-2, who underwent circumcision and received a caudal injection comprising 1.5 mL/kg of 0.15% ropivacaine and 5 µg/mL of epinephrine after anesthesia induction. The no-clonidine (NC) group received no additional caudal additive, whereas the clonidine (C) group received 1 µg/mL of clonidine. The research team instructed the patients' parents to administer oral acetaminophen when they detected a pain level corresponding to a visual analog scale score ≥4 on the Wong-Baker FACES Pain Rating Scale or when they felt that their child was uncomfortable. EA occurrence was measured by post-anesthesia care unit nurses using the Pediatric Anesthesia Emergence Delirium (PAED) scale.

No significant differences were observed between the two groups regarding demographics, anesthesia, surgery, or discharge time. The median time to the first postoperative acetaminophen dose was 335 min for the NC group and 381 min for the C group (P = 0.901). The NC group had a mean PAED score of 6.5 compared with 6.4 in the C group (P = 0.894).

In children who underwent circumcision, adding clonidine to the HVLC caudal injection of ropivacaine did not prolong the time to the first acetaminophen dose or the occurrence of EA, suggesting no benefit in using clonidine in this surgical population.