A prospective randomised controlled study comparing intra-operative and post-operative analgesic efficacy of clonidine with bupivacaine for caudal block in paediatric surgical procedures at Kenyatta National Hospital

Abstract

Caudal analgesia is the most popular and commonly used regional block in paediatric surgery. It continues to offer a safe and effective intra and postoperative analgesia for many surgical procedures in the region of the umbilicus and below. The use of local anaesthetics in combination with opioids has been demonstrated to improve caudal analgesia in children but has also been associated with side effects such as nausea and vomiting, pruritus, urinary retention, and potentially life threatening respiratory depression. Clonidine, an alpha, agonist has been used effectively for the treatment of acute and chronic pain. It has been shown to provide analgesia of variable efficacy and duration and to potentiate postoperative analgesia when used in combination with local anaesthetics or opioids via extradural and intradural routes. Furthermore, it lacks side effects that are associated with the use of systemic and spinal opioids but does demonstrate adverse effects including sedation, hypotension, and bradycardia. This study was designed to compare the analgesic efficacy and incidences of side effects of clonidine with bupivacaine. It was a prospective randomized controlled study, which was carried out at Kenyatta National Hospital (KNH) over a period of two months. The study subjects were the paediatric patients aged two months to thirteen years scheduled for elective surgery. Statistical analysis was performed using chi square test for nominal data. Continuous data was compared using Kruskal-wallis one-way analysis of variance (ANOV A). P<0.05 was considered significant. Sixty patients aged 2 months to 13 years were randomly allocated to three equal groups to receive 0.25% bupivacaine 1ml kg" body weight (group B), -j clOl2-idine2~Lkg" body weight (group C) and 0.12'5% bupivacaine 1ml kg' body weight combined with clonidine 1).1 kg' body weight (group BC). The median time for duration of analgesia was 5.18 hours for group B, 6.17 hours for group C and 8.03 hours for group BC (P<O.OOl).There was a significant difference in the incidence of side effects between the three groups. The median time to first micturition and ambulation was significantly higher in group B as compared to groups C and BC (P<O.OOI). The incidence of sedation was higher in groups BC and C as compared to group B. This resulted partly from the longer duration of analgesia provided by clonidine and the clonidine bupivacaine mixture as well as the sedative effect of clonidine. It was concluded that the analgesic efficacy of clonidine is better than bupivacaine and that a combination of clonidine and bupivacaine in lowered dosages improves the efficacy of caudal analgesia in children with reduced incidences of side effects.