Caudal neostigmine with bupivacaine produces a dose-independent analgesic effect in children.

PURPOSE: To evaluate the analgesic efficacy and duration of varying doses of caudal neostigmine with plain bupivacaine and its side effects in children undergoing genito-urinary surgery.

METHODS: In a randomized double-blind prospective study 80 boys aged two to eight years scheduled for surgical repair of hypospadias were allocated randomly to one of four groups (n = 20 each) and received either only caudal 0.25% plain bupivacaine 0.5 mL.kg(-1) (Group I) or 0.25% plain bupivacaine 0.5 mL.kg(-1) with neostigmine (Groups II-IV) in doses of 2, 3 and 4 microg.kg(-1) respectively. Postoperative pain was assessed for 24 hr using an objective pain score. Blood pressure, heart rate, oxygen saturation, total amount of analgesic consumed and adverse effects were also recorded.

RESULTS: The duration of postoperative analgesia in Group I (5.1 +/- 2.3 hr) was significantly shorter than in the other three groups (II -16.6 +/- 4.9 hr; III - 17.2 +/- 5.5 hr; IV - 17.0 +/- 5.8 hr; P < 0.05). Total analgesic (paracetamol) consumption was significantly more in Group I (697.6 +/- 240.7 mg) than in the groups receiving caudal neostigmine (II - 248.0 +/- 178.4; III - 270.2 +/- 180.8 and IV -230.6 +/- 166.9 mg; P < 0.05). Groups II, III and IV were comparable with regards to duration of postoperative analgesia and total analgesic consumption (P > 0.05). Incidence of nausea and vomiting were comparable in all four groups. No significant alteration in vital signs or any other adverse effects were observed.

CONCLUSIONS: Caudal neostigmine (2, 3 and 4 microg.kg(-1)) with bupivacaine produces a dose-independent analgesic effect ( approximately 16-17 hr) in children as compared to those receiving caudal bupivacaine alone (approximately five hours) and a reduction in postoperative rescue analgesic consumption without increasing the incidence of adverse effects.