The impact of caudally administrated tramadol on immune response and analgesic efficacy for pediatric patients: a comparative randomized clinical trial

Background: Immune responses appear to be affected by anesthetics and analgesics. We investigated the effects of caudal tramadol on the postoperative immune response and pain management in pediatric patients. Methods: Sixty ASA-I pediatric patients aged 3-10 years undergoing lower abdominal surgery. Patients were randomly assigned either to a caudal bupivacaine (0.25%) group (group B), or a group that received caudal tramadol (1 mg/kg) added to the bupivacaine (0.25%) (group T). Both were diluted in a 0.9% NaCl solution to a total volume of 1ml/ kg. The systemic immune response was measured by collecting blood samples preoperatively, at the end of anesthesia, and at 24 and 72 hours postoperatively, and studied for interleukin IL-6, C-reactive proteins (CRP) cortisol levels, and leucocytes with its differential count. Postoperative pain was assessed along with sedation scales. Results: Postoperative production of IL-6 was significantly higher in group B at the end of anesthesia, than at the 24th hour, and at the 72nd hour in group B and group T, respectively. The immune response showed leukocytosis with increased percentages of neutrophil and monocytes, and a decreased lymphocyte response rate within both groups with no significant differences between the groups. Cortisol and CRP were significantly higher in group B. Conclusions: Adding tramadol to a caudal bupivacaine block can attenuate the pro-inflammatory cytokine response, Cortisol, and CRP in children undergoing lower abdominal surgery. (Korean J Pain 2018; 31: 206-14)