Caudal additives for postoperative pain management in children: S(+)-ketamine and neostigmine

Background: The aim of the present pilot study was to compare the analgesic efficacy of S(+)-ketamine either alone or in combination with neostigmine for caudal blockade in pediatric surgery. Methods: A total of 40 children were randomly assigned to receive after induction of general anesthesia either caudal S(+)-ketamine 1 mg.kg(-1) (group K, n = 20) or caudal S (+)-ketamine 0.5 mg.kg(-1) plus neostigmine 10 mug.kg(-1) (group KN, n = 20). Anesthesia was maintained with sevoflurane and a laryngeal mask airway (LMA(TM)), no additional analgesics were administered. Postoperative pain and sedation were assessed by the Children's Hospital of Eastern Ontario Pain Score and Ramsay scale for 24 h. Results: No statistical difference in duration of analgesia and sedation was found. Mean duration of postoperative analgesia was 18 +/- 9.4 h in group K and 21.8 +/- 6.7 h in group KN. There was a significantly higher incidence of postoperative vomiting after administration of caudal ketamine with neostigmine (30% group KN Vs 0% group K; P < 0.05). Conclusions: This pilot study demonstrates equianalgesic effects on postoperative pain relief in children with both caudal S(+)-ketamine 1 mg.kg(-1) and caudal S(+)-ketamine 0.5 mg.kg(-1) plus neostigmine 10 mug.kg(-1). Further studies are required to confirm adoption of caudal neostigmine into routine clinical practice.