Preservative-free racemic ketamine with bupivacaine: a desirable option for extended caudal analgesia in pediatric surgery

Introduction Caudal epidural block is a commonly performed procedure in pediatric anesthesia worldwide. Ketamine is used as an adjuvant in single-shot caudal blocks to prolong postoperative analgesia. Aims of the study This randomized double-blind study was carried out to evaluate the effect of the addition of preservative-free racemic ketamine 0.5 mg/kg to 0.25% bupivacaine (1 ml/kg) in caudal block on the duration of postoperative analgesia in pediatric patients and to observe adverse effects, if any. Materials and methods Sixty children, aged 2–9 years, undergoing infraumbilical surgical procedures were assigned randomly to one of two groups, B or BK, to receive 1 ml/kg of 0.25% bupivacaine or a mixture of 0.5 mg/kg of preservative-free racemic ketamine with 1 ml/kg of 0.25% bupivacaine, respectively, for single-shot caudal anesthesia. The postoperative pain score was assessed. Sedation, motor weakness, and other adverse effects were also observed. Observations and results The mean duration of analgesia was significantly longer (P < 0.01) in group BK (12.933 h) than in group B (3.467 h). The incidences of adverse effects such as urinary retention, vomiting, and motor weakness were comparable in the two groups (P > 0.05). Conclusion Preservative-free racemic ketamine at a dose of 0.5 mg/kg may be used as a safe and reliable adjunct to caudal bupivacaine for prolongation of postoperative analgesia in children. As racemic ketamine is less expensive and more easily available than S(+)-ketamine, further studies comparing their cost-effectiveness may help to establish the racemic preparation as an appropriate adjuvant for single-shot caudal analgesia, especially in nations where cost constraints exist.