Ketamine has no pre-emptive analgesic effect in children undergoing inguinal hernia repair

Previous studies have suggested that ketamine, an n-methyl-d-aspartate (nmda) receptor antagonist, provides a pre-emptive analgesic effect and pre-emptive analgesia improves postoperative pain management. The aim of this study was to determine the effict of pre-incisional vs. post-incisional intravenous low dose of racemic ketamine in postoperative pain in children undergoing inguinal hernia repair. Seventy-five children aged 1-6 years who were scheduled for inguinal herniorrhaphy were included in a prospective, double-blind randomized controlled trial. Patients were randomly allocated to three groups (pre-incisional, post-incisional and control). Patients in pre-incisional group received an intravenous bolus of racemic ketamine (0.25 mg/kg) before surgical incision and patients in post-incisional group received the same dose of racemic ketamine after surgical incision. Children of control group received intravenous boluses of normal saline. In post anesthesia care unit and pediatric surgical ward, the degree of pain and sedation, additional analgesic requirements and side effects were evaluated. There were no differences between groups with respect to demographic and hemodynamic parameters. Pain and sedation scores were not statistically different between groups during 24 h study. In addition, there was no significant difference among groups in number of supplementary analgesic requirements and postoperative nausea and vomiting in the first 24 h. No other side effects were reported during the study period. We found that low dose racemic ketamine administered prior to surgical incision has no pre-emptive effect on post-operative pain and supplementary analgesic requirement during the first 24 h after herniorrhaphy in pediatric patients.