ADDITION OF CLONIDINE OR FENTANYL TO LOCAL-ANESTHETICS PROLONGS THE DURATION OF SURGICAL ANALGESIA AFTER SINGLE-SHOT CAUDAL BLOCK IN CHILDREN

Caudal anaesthesia is indicated for surgical procedures lasting less t han 90 min. Fentanyl and clonidine are known to prolong postoperative caudal analgesia, but there are no data on their effect on duration of surgical analgesia. We evaluated if the addition of clonidine or fent anyl to local anaesthetics prolonged the duration of surgical analgesi a after single shot caudal block in children in a randomized, double-b lind study. We studied 64 children, aged 6-108 months, undergoing bila teral correction of vesicoureteral reflux which was expected to last m ore than 90 min. Patients were allocated to one of four groups: group O received 1 ml kg(-1) of a mixture of 0.25% bupivacaine with epinephr ine and 1% lidocaine in equal parts; group F received the same mixture of local anaesthetics in addition to fentanyl 1 mu g kg(-1); group C received the same mixture of local anaesthetics in addition to clonidi ne 1.5 mu g kg(-1); and group C+F received the same mixture of local a naesthetics in addition to fentanyl 0.5 mu g kg(-1) and clonidine 0.75 mu g kg(-1) Single shot caudal block was sufficient in only 57% of ch ildren in group O compared with 93% in groups C and F and 86% in group C+F (P = 0.035). Global assessment of anaesthesia, defined as the tim e from caudal injection to the first administration of analgesic (eith er during or after surgery), was significantly longer in the three gro ups of children who received additives compared with local anaesthetic s alone (P = 0.035), but there were no differences between the three a dditive groups. Vomiting was observed only in children who received fe ntanyl. Addition of clonidine or fentanyl to local anaesthetics prolon ged the duration of surgical analgesia of caudal block, allowing singl e shot caudal anaesthesia to be recommended for surgery lasting 90-150 minutes. Clonidine had some advantages over fentanyl as it did not pr oduce clinically significant side effects.