Refining caudal catheterization for anorectal surgery: a comparative study of a technique to optimize sensory block and minimize motor impairment

BACKGROUND: The application of caudal epidural catheterization for anorectal surgery has not been systematically investigated. METHODS: We performed a retrospective chart review of adult patients undergoing elective anorectal surgery under caudal epidural anesthesia at our institution. 163 patients who received conventional single-injection caudal anesthesia (20 mL of 5 mg/mL ropivacaine) and 62 patients who received our refined catheterization technique were included. In the refined group, an initial height-based dose of 5 mg/mL ropivacaine (10-16 mL according to patient height) was administered through a Tuohy needle, followed by 2 cm cephalad catheterization; additional 5 mg/mL ropivacaine was then titrated via the catheter until complete sensory blockade of the surgical site was achieved. To compare the two techniques while minimizing selection bias, we performed inverse probability of treatment weighting (IPTW). Anesthetic efficacy, sensory block level, lower limb motor block, and procedure-related complications were assessed. RESULTS: The refined technique demonstrated comparable anesthetic efficacy to conventional caudal anesthesia (Grade I anesthetic efficacy: 86.8% vs. 85.6%; OR = 1.11, 95% CI: 0.46-2.66, p = 0.820). The refined technique significantly improved preservation of lower extremity motor function, with a higher rate of no motor block (84.7% vs. 71.7%; OR = 2.18, 95% CI: 1.01-4.71, p = 0.047) and higher level of Sensory block (median S2 vs. S3; OR = 2.24, 95% CI: 1.33-3.77, p = 0.002). CONCLUSION: Compared with conventional single-injection caudal anesthesia, the refined caudal catheterization regimen provides non-inferior anesthetic efficacy, superior preservation of lower extremity motor function.