Caudal clonidine added to local anaesthetics for post-operative analgesia after anal surgery in adults - abstract

Duration of postopertive analgesia with caudal local anesthetics is increased by the addition of clonidine in children. To assess its efficacy in adults, we undertook a prospective, randomized, double-blind study in adults undergoing elective haemorrhoidectomy. Fifty-eight patients were randomly allocated to one of two groups. Caudal anaesthesia was performed with 0.5 percent isobarbic bupivacaine 35 mg (7 ml) in 2 percent lidocaine 140 mg (7 ml) and epinephrine 1/200000. Clonidine 75 mg was added in Group C, and saline (1ml) in group S. Duration of analgesia, defined as the time from the caudal injection to the first request for supplemental analgesics, was recorded as well as the time for the first micturition, haemodynamic changes and sedation. No differences were found between groups for demographic data, sedation and the time to first micturition. The mean (±SEM) duration of analgesia was longer in group C(729 ± 120 min) than in group S (276 ± 131 min) (p=0.01). Hypotension and sedation was not marked in our study. Bradycardia was more frequent in the clonidine group but had no haemodynamic repercussions. We conclude that the duration of postoperative analgesia with caudal local anaesthetics was significantly increased by the addition of 75 mg of clonidine without major side effects. (AU)