Caudal anesthesia in pediatrics: an update

Caudal anesthesia is one of the most used-popular regional blocks in children. This technique is a useful adjunct during general anesthesia and for providing postoperative analgesia after infraumbilical operations. The quality and level of the caudal blockade is dependent on the dose, volume, and concentration of the injected drug. Although it is a versatile block, one of the major limitations of the single-injection technique is the relatively short duration of postoperative analgesia. The most frequently used method to further prolong postoperative analgesia following caudal block is to add different adjunct drugs to the local anesthetics solution. Only few studies evaluated quality and duration of caudal block against the volume of the local anaesthetic applied. After reviewing recent scientific literature, the authors compare the duration of postoperative analgesia in children scheduled for hypospadia repair when 2two different volumes and concentrations of a fixed dose of ropivacaine are used.

After informed parental consent, 30 children (ASA I, 1-5 years old) were enrolled in a multicentre, perspective, not randomized, observational study conducted in two 2 children hospitals. After premedication with midazolam, anesthesia was induced with thiopental and maintained with sevoflurane in oxygen/air. After induction, patients received a caudal blockade either with ropivacaine 0.375% at 0.5 mL/kg (Low Volume High Concentration Group, LVHC; n = 15), or ropivacaine 0.1% at 1.8 mLl/kg (High Volume Low Concentration Group, HVLC; n = 15). Surgery was allowed to begin 10ten minutes after performing the block. MAC-hour was calculated. In the recovery room, pain was assessed using the Children's Hospital of Eastern Ontario Pain Scale (CHEOPS). In addition, the motor block was scored. After transferral to the ward, the patients were observed for 24 hours for signs of postoperative pain. The time period to first supplemental analgesic demand, i.e., from establishment of the block until the first registration of a CHEOPS score = or > 9, was considered the primary endpoint of the study. The time periods were compared using analysis of variance adjusted for age, weight and duration of surgical procedure as covariates.

All patients were judged to have sufficient intraoperative analgesia, and none of them received additional analgesics intraoperatively. Patients' characteristics were similar, besides the age (32+/-10 vs 24 +/- 9 months; P < 0.05) and weigh (15.13 +/- 3.92 vs 11.93 +/- 1.83; P = 0.08). Analgesics were needed after 520 +/- 480 min in the LVHC and 952 +/- 506 min in the HVLC group (P < 0.05). Motor block was less in the HVLC group.

In children undergoing hypospadia repair, caudal block with a ''high volume, low concentration'' regimen produces prolonged analgesia and less motor block, compared to a ''low volume, high concentration'' regimen.