Systemic intraoperative lidocaine infusion for postoperative pain management in obese patients: A randomized, placebo controlled pilot study

Background: Systemic intraoperative lidocaine has been seen to decrease postoperative pain following abdominal surgery, butfew studies have examined its use in morbidly obese patients. Objective: We sought to evaluate the safety and effects of intravenous lidocaine in obese patients undergoing laparoscopicRoux-en-Y gastric bypass (RYGB) surgery. Methods: Setting: University-affiliated, private hospital, United States. In this preliminary prospective, double-blinded, andplacebo-controlled safety study, we enrolled 21 patients and 20 completed the study. Ten patients were randomly assigned to thestudy group and received a continuous infusion of lidocaine intravenously from induction of general anesthesia until the endof the operation. Ten other patients were assigned to the control group and received a dextrose placebo intravenously over thesame time period. Subjects were followed for 24 hours postoperatively. The primary endpoint was the presence of symptoms oflidocaine toxicity at 1 hour postoperatively. Exploratory outcomes were adverse events, visual analog scale (VAS) pain scores,opioid consumption, time to first passage of flatus and bowel movement, and length of hospital stay. Results: No significant differences were seen between groups for overt signs of lidocaine toxicity or adverse events, opioidconsumption, postoperative pain scores, time to first passage of flatus or first bowel movement, or length of hospital. We identifieda trend towards less opioid consumption in patients receiving lidocaine. We were underpowered to detect statistical differencesdue to our pilot study design; addressing safety as the primary outcome measure as opposed to efficacy. Conclusions: In this study, intravenous lidocaine in RYGB surgery was found to be safe without differences in postoperativepain or adverse effects.