A comparison between intravenous lidocaine and ketamine on acute and chronic pain after open nephrectomy: A prospective, double-blind, randomized, placebo-controlled study

BACKGROUND: Recently, there has been increasing interest in the use of analgesic adjuncts such as intravenous (IV) ketamine and lidocaine. OBJECTIVES: To compare the effects of perioperative IV lidocaine and ketamine on morphine requirements, pain scores, quality of recovery, and chronic pain after open nephrectomy. STUDY DESIGN: A prospective, randomized, placebo-controlled, double-blind trial. SETTINGS: The study was conducted in Charles Nicolle University Hospital of Tunis. METHODS: Sixty patients were randomly allocated to receive IV lidocaine: bolus of 1.5 mg/kg at the induction of anesthesia followed by infusion of 1 mg/kg/h intraoperatively and for 24 h postoperatively or ketamine: bolus of 0.15 mg/kg followed by infusion of 0.1 mg/kg/h intraoperatively and for 24 h postoperatively or an equal volume of saline (control group [CG]). MEASUREMENTS: Morphine consumption, visual analog scale pain scores, time to the first passage of flatus and feces, postoperative nausea and vomiting (PONV), 6-min walk distance (6MWD) at discharge, and the incidence of chronic neuropathic pain using the “Neuropathic Pain Questionnaire” at 3 months. RESULTS: Ketamine and lidocaine reduced significantly morphine consumption (by about 33% and 42%, respectively) and pain scores compared with the CG (P < 0.001). Lidocaine and ketamine also significantly improved bowel function in comparison to the CG (P < 0.001). Ketamine failed to reduce the incidence of PONV. The 6 MWD increased significantly from a mean ± standard deviation of 27 ± 16.2 m in the CG to 82.3 ± 28 m in the lidocaine group (P < 0.001). Lidocaine, but not ketamine, reduced significantly the development of neuropathic pain at 3 months (P < 0.05). CONCLUSION: Ketamine and lidocaine are safe and effective adjuvants to decrease opioid consumption and control early pain. We also suggest that lidocaine infusion serves as an interesting alternative to improve the functional walking capacity and prevent chronic neuropathic pain at 3 months after open nephrectomy.