(1) Objectives: the purpose of this study is evaluation of analgesic effects of intravenous infusion of Lidocaine and Ketamine during surgery on acute pain after elective laparotomy surgery. (2) Design: this study is a double-blind randomized controlled trial and will be accomplished in Hazrat-e-rasool akram hospital in Tehran, Iran between 2013 and 2014. This trial is a phase III study. The participants are 80 patients, both male and female.The patients will be divided in two groups based on random number table. In one group Lidocaine and Ketamine will be infused during surgery and in the other group general anesthesia will just be induced. (3) Setting and conduct: in one group after induction of general anesthesia, intravenous Lidocaine and Ketamine will be infused during surgery with assigned doses. In the other group general anesthesia will just be induced. (4) Inclusion criteria: ASA I, ASA II, Hb>10, age between 20 and 60. Exclusion criteria: hemodynamic instability, uncontrolled underlying disease, drug sensitivity, addiction to alcohol and opioids. (5) Intervention: in one group, 30 minutes after induction of general anesthesia, both drugs Lidocaine and Ketamine will be infused intravenously with the dose of 0.5 mg/kg/hr until termination of surgery. In the other group these drugs will not be infused and general anesthesia will just be induced. (6)
Main outcome measures: for evaluation of efficacy of intervention on rate of pain, visual analogue scale (VAS) will be used. Side effects including cardiac arrhythmia, seizure, halucination, delirium, and drug sensitivity will be evaluated in patients.