THE OPTIMAL DOSE OF KETAMINE FOR CAUDAL EPIDURAL BLOCKADE IN CHILDREN

Sixty boys aged up to 9 years undergoing orchidopexy were randomly all ocated to receive one of three solutions for caudal epidural injection : group A received 1 ml.kg(-1) of 0.25% bupivacaine with 0.25 mg.kg(-1 ) of preservative-free ketamine, group B received 1 ml.kg(-1) of 0.25% bupivacaine with ketamine 0.5 mg.kg(-1) and group C received 1 ml.kg( -1) of 0.25% bupivacaine with 1 mg.kg(-1) of ketamine. Postoperative p ain was assessed by means of a modified Objective Pain Score and analg esia was administered if this score exceeded four. The median duration of caudal analgesia was 7.9 h in group A. 11 h in group B and 16.5 h in group C. There were no differences between the groups in the incide nce of motor block, urinary retention, postoperative vomiting or posto perative sedation. Group C had a significantly higher incidence of beh avioural side effects, including slightly odd behaviour, vacant stares and abnormal effect than groups A and B.