Pre-Incisional Analgesia with Intravenous or Subcutaneous Infiltration of Ketamine Reduces Postoperative Pain in Patients after Open Cholecystectomy: A Randomized, Double-Blind, Placebo-Controlled Study

BACKGROUND: In literature, there is controversy on the use of ketamine for management of postoperative pain. The aim of the present study was to evaluate the efficacy of pre-incisional intravenous or subcutaneous infiltration of ketamine on postoperative pain relief after open cholecystectomy. METHODS: One hundred twenty patients, aged 18-60 years, scheduled for open cholecystectomy was enrolled in this randomized, double-blind, placebo-controlled study. Patients were divided into four groups of 30 each and received subcutaneous infiltration of ketamine 1 mg/kg (group KS1), subcutaneous infiltration of ketamine 2 mg/kg (group KS2), intravenous ketamine 1 mg/kg (group KI), or subcutaneous infiltration of normal saline 20 mL (group C) before surgery. Visual analog scale (VAS) values and analgesic consumption were evaluated for 24 hours after operation. RESULTS: VAS scores were significantly lower at arrival to the postanesthesia care unit, 15 and 30 minutes in Group KS1, Group KS2, and Group KI compared with Group C (P<0.05). In Group KS2, VAS scores were significantly lower than Group KS1 (P<0.05). Postoperative VAS scores were significantly lower at 1, 2, 3, 4, 8, 12, and 24 hours after operation in Group KS1, Group KS2, and Group KI compared with Group C (P<0.05). In Group KS2, VAS scores were significantly lower than Group KS1 (P<0.05). CONCLUSION: A 2 mg/kg dose of subcutaneous infiltration ketamine or 1 mg/kg dose of intravenous ketamine given at approximately 15 minutes before surgery provides an adjunctive analgesia during 24 hours after surgery in patients undergoing cholecystectomy surgery.