A Comparative Study of Clonidine and Neostigmine as Additives to Bupivacaine in Caudal Analgesia in Children

Background: Caudal anesthesia is the most frequently used regional technique in children, accounting for almost 50% of all regional techniques. But a single caudal injection provides analgesia only for the duration of action of the local anesthetic. In a prospective randomized double-blind clinical study, we assessed and compared the efficacy of neostigmine and clonidine co-administered with bupivacaine in a caudal epidural to provide intraoperative and postoperative pain relief.Methods: Sixty boys, ASA physical status I, aged 3-8 yr, scheduled to undergo elective unilateral groin surgery were allocated randomly to one of three groups (n=20) to receive the following drugs by the caudal route; group bupivacaine (B) 0.25% plain bupivacaine 1 ml/kg; group bupivacaine- clonidine (BC) 0.25% plain bupivacaine 1 ml/kg with clonidine 2μ/kg and group bupivacaine-neostigmine (BN) 0.25% plain bupivacaine 1 ml/kg with neostigmine 2μ/kg. Postoperative pain was assessed for 24 hr using an objective pain score. Blood pressure, heart rate, oxygen saturation, the duration of absolute analgesia, the time to first analgesic, total amount of analgesic consumed and adverse effects were also recommended.Results: Both the duration of absolute analgesia and the time to first analgesic was significantly prolonged in group BN (7.9±3.8 h; 19.6±4.2 h) and group BC (6.8±3.3 h; 16.8± 3.9 h) compared with group B (4.5±2.8 h; 7.6±5.2 h) (p 0.01) (p 0.001) respectively. The bupivacaine group received more doses of paracetamol than the bupivacaine/clonidine and bupivacaine/neostigmine groups to maintain adequate analgesia in the first 24 postoperative hours with highly significant difference in between (p 0.01). No significant alteration in vital signs or adverse effects were observed.Conclusion: We concluded that the addition of clonidine (2μ/kg) or neostigmine (2μ/kg) to caudal bupivacaine significantly prolongs the duration of effective analgesia. The effect is more pronounced with neostigmine.