Clonidine addition prolongs the duration of caudal analgesia

Abstract

Background: In this study, using a dose-ranging design, we examined the effects of clonidine with 0.125% bupivacaine on the duration of post-operative analgesia in caudal anaesthesia in children.

Methods: We conducted a controlled, prospective study of clonidine in caudal anaesthesia in 60 children, aged 1-10 years, undergoing elective inguinal hernia repair. Induction and maintenance of anaesthesia were performed by inhalation of sevoflurane and nitrous oxide. The children were randomized in a double-blind fashion to four groups, and were given a caudal anaesthetic with either 0.125% plain isobaric bupivacaine (1 ml/kg) or bupivacaine plus 1, 1.5 or 2 microg/kg of clonidine. The blood pressure and heart rate were recorded peri-operatively. Analgesia was evaluated by the modified Children's Hospital of Eastern Ontario Pain Scale (mCHEOPS) or a visual analogue scale (VAS). Paracetamol was given when the mCHEOPS score was greater than five or when the VAS score was greater than 30 mm. The monitoring of scores for pain, haemodynamic changes and post-operative nausea and vomiting was performed by nurses blind to the study allocation.

Results: The duration of analgesia was found to be significantly longer in the group given bupivacaine plus 2 microg/kg of clonidine (median, 650 min; range, 300-900 min). Peri-operative hypotension and bradycardia, post-operative respiratory depression and motor block were not recorded in any patient.

Conclusions: The addition of clonidine to 0.125% bupivacaine prolongs the duration of post-operative analgesia without any respiratory or haemodynamic side-effects.