Caudal ropivacaine and ketamine for postoperative analgesia in children.

In a prospective, randomised, double-blind clinical study, we studied 32 ASA grade I and II boys aged 18 months to 12 years, scheduled for circumcision under general anaesthesia on an outpatient basis. They were randomly allocated to one of two groups: those in the ropivacaine group received caudal ropivacaine 0.2% 1 ml. kg-1 for postoperative analgesia and those in the ketamine/ropivacaine group received caudal ropivacaine 0.2% 1 ml. kg-1 plus caudal ketamine 0.25 mg.kg-1. Postoperative pain was assessed using a modified 10-cm visual analogue scale and analgesia was administered if the pain score exceeded a value of 3. The median duration of analgesia was significantly longer in the ketamine/ropivacaine group (12 h) than in the ropivacaine group (3 h, p < 0.0001), and subjects in the ropivacaine group required significantly more doses of postoperative analgesia than those in the ketamine/ropivacaine group (p < 0.0001). There were no differences between the groups in the incidence of postoperative nausea, vomiting, sedation, emergence delirium, nightmares, hallucinations, motor block and urinary retention.