Background: Ketamine has been shown to prolong analgesia produced by caudal local anaesthetic block and is now in common use. This study compares caudal block using bupivacaine/ketamine with dorsal nerve block of the penis.
Methods: Sixty boys undergoing elective circumcision were given either 0.5 ml x kg-1 of bupivacaine 0.15% with ketamine 0.5 mg x kg-1 (n = 30) or dorsal nerve block of the penis with bupivacaine 0.5% (n = 30) as a supplement to general anaesthesia. Postoperative pain was assessed by parents using a modified objective pain score, and the time taken to first requirement of analgesia was recorded. Motor weakness, time to first micturition, postoperative nausea and vomiting (PONV), eating habits, sleep disturbance and behaviour were also assessed.
Results: There was no difference between the groups in time to first requirement for analgesia or number of doses of paracetamol given in the first 24 h. Almost half the boys in the caudal group had motor weakness, and there was a significant increase in time to first micturition in that group. There was no difference between the groups in PONV, eating, sleeping or behavioural disturbance.
Conclusions: Caudal anaesthesia with bupivacaine/ketamine does not confer any advantage over a dorsal nerve block with the doses used in this study. Because of the higher incidence of side-effects and technique failure in the caudal group, dorsal nerve block is perhaps the preferred technique.