Preincisional subcutaneous infiltration of ketamine suppresses postoperative pain after circumcision surgery

Objective: N-methyl-D-aspartate and other glutamate receptors have been shown to present on the peripheral axons of primary afferents, and peripheral injection of N-methyl-D-aspartatereceptor antagonists can suppress hyperalgesia and allodynia. Thus, this study examined postoperative analgesic and adverse effects of local ketamine administered postoperatively. Methods: Ketamine (0.3%, 3 mL) or saline was subcutaneously infiltrated before incision in a double-blind manner using a sample population of 40 patients undergoing circumcision surgery, equally and randomly assigned to 2 groups based on the treatment. The saline-infiltrated patients also received 9-mg intramuscular ketamine into the upper arm to control for any related systemic analgesic effects. The patients were followed up for 24 hours to determine postoperative analgesia and identify adverse effects. Results: In the ketamine-infiltrated patients, the time interval until first analgesic demand (166 vs. 80 min) was longer and the incidence of pain-free status (pain score = 0) during movement (45% vs. 10%) and erection (40% vs. 0%) was significantly higher than for the saline-treated analogs (P < 0.05). The dose of ketorolac use and pain score during erection were significant lower in group ketamine patients. No significant differences were noted with respect to the incidence of adverse effects comparing the 2 groups. Discussion: We conclude that preincisional subcutaneous ketamine infiltration can suppress postoperative pain after the circumcision surgery.