A randomized-controlled, double-blind study to evaluate the efficacy of caudal midazolam, ketamine and neostigmine as adjuvants to bupivacaine on postoperative analgesic in children undergoing lower abdominal surgery

Background: Caudal epidural is the most commonly used technique for the management of postoperative pain in children. The aim of the present study was to assess and compare the efficacy of caudal bupivacaine as a postoperative analgesic alone or combined with midazolam, ketamine, and neostigmine in pediatric patients undergoing lower abdominal surgery. Methods: Eighty pediatric patients categorized under the American Society of Anesthesiologists Physical Status I and II Classification System, who have been scheduled to undergo lower abdominal surgery were randomly designated into four groups to receive caudal block with either 1 ml/kg of 0.25% caudal bupivacaine for group B, 1 ml/kg of 0.25% caudal bupivacaine mixed with 2 μg/kg neostigmine for group BN, 1 ml/kg of 0.25% caudal bupivacaine mixed with 0.5 mg/kg ketamine for group BK or 1 ml/kg of 0.25% caudal bupivacaine mixed with 50 mcg/kg midazolam for group BM. Postoperative analgesia was examined by a blinded anesthetist utilizing a Revised Faces Pain Scale. Consumption of the total amount of rescue analgesic each 24 h, postoperative time to requirement of the first dose and any adverse effects were noted. Results: The four groups were comparable as regards age, sex, weight, duration of surgery, heart rate, blood pressure and the time from induction of anesthesia to response to voice. The Revised Faces Pain Scale was 2.6±1.5 in group BN, 3.1±1.8 in group BM, 4.4±2.4 in group BK, and 5.6±1.3 in group B (p=0.005). Postoperative duration of analgesia was 433±68 min, 769±118 min, 1097±126 min and 1254±176 min in groups B, BK, BM and BN respectively (P=0.001). The dose of rescue analgesic within 24 h in group B was significantly higher than those of the other three groups (P<0.05). Conclusion: Addition of either neostigmine, midazolam, or ketamine to caudal bupivacaine extended analgesia time and decreased rescue analgesic compared to bupivacaine alone in children who underwent lower abdominal surgery. (www.actabiomedica.it)