The efficacy of caudal morphine or bupivacaine combined with general anesthesia on postoperative pain and neuroendocrine stress response in children

BACKGROUND: The aim of this study was to compare the effectiveness of caudal morphine and bupivacaine usage on surgical stress response in children undergoing abdominal and genitourinary surgery while keeping anesthesia depth constant utilizing the bispectral index analysis (BIS). METHODS: Following the approval of Institutional Review Board and informed parental consent, 28 children with ages ranging between 4 and 16 years with ASA physical status I and II , undergoing elective lower abdominal and genitourinary surgery were included in this study. Patients were randomized and separated into two subgroups. Before induction of anesthesia, patients were monitored for BIS. Epidural injection of 30 microg.kg(-1) morphine in 1 ml.kg(-1) saline for the first group (group M) and the same volume of (0.25%) bupivacaine for second group (group B) were administered via the sacral hiatus. We analyzed serum cortisol and glucose concentrations for evaluation of the stress response in the patients. Blood samples for cortisol and glucose were withdrawn at the beginning of induction (first samples), 40 min after surgical incision (second samples), and 40 min after end of the surgery (third samples). BIS scores of the patients were kept between 40 and 60 during the surgical procedure. RESULTS: Group B had significantly lower levels of cortisol than group M in the second samples. There was a significant increase in serum glucose level in group M compared with group B during the intraoperative and postoperative periods. CONCLUSIONS: We conclude that, caudal administration of bupivacaine is more effective than morphine for attenuating intraoperative and postoperative stress response to surgery in children.