Intravenous Lidocaine in Bariatric Surgery.

This is a prospective, double-blind, placebo-controlled, monocentric study. We plan to recruit 180 obese adult patients scheduled for bariatric surgery in a the french university hospital of Caen.

Exclusion: contra-indications for any aminoamide local anesthetic (allergy, severe hepatic disease) and for intravenous lidocaine (porphyria, atrioventricular conduction disturbances, uncontrolled seizure disease), long term opioid consumption, need for a post-operative follow-up in an intensive care unit, combined surgical procedure excepting cholecystectomy, pregnancy.

Patients will be randomly allocated to receive either a saline placebo or lidocaine continuous infusions during surgery. Morphinic consumption will be assessed from the end of the procedure until the third day after surgery. Secondary criteria will concern post-operative recovery, pain and postoperative nausea and vomiting, other medical and surgical complications, and toxicity. Plasma lidocaine concentrations will be measured in patients who had received lidocaine in order to determine the safety and efficiency of our infusion protocol.

Our analysis will be a superiority one, alpha risk is 5% and beta risk is 20%, in intention to treat, with no intermediate analysis.

Inclusion criteria

• scheduled bariatric surgery

Exclusion criteria

• any contra-indication for lidocaine administration
• pregnancy
• ASA class 4
• psychiatric disorder
• chronic opioid consumption