Inclusion Criteria:

• American Society of Anesthesiologists (ASA) I to III
• requires bariatric surgery
• body mass index (BMI) >= 35 kg/m2
• patient speaks and writes French
• patient has signed consent form
• patient enrolled in a social security program

Exclusion Criteria:

• patient refuses to sign consent
• ASA IV or more
• patient is pregnant or breastfeeding
• history of hyperthermy (or suspicion, or family history thereof)
• history of liver disease, icterus, unexplained fever, or eosinophilia after administration of a halogen anesthesia
• patient has symptomatic gastro-oesophagean reflux
• patient has hypersensitivity to one or more of the following substances: propofol, remifentanil, celocurine, cisatracurium, rocuronium, desflurane, xenon, paracetamol, ketoprofen, nefopam, tramadol
• patient has obstructive respiratory failure (chronic obstruction pneumopathy, asthma) or has heart disease with severly altered cardiac function
• patient has high intracranial pressure
• patient requires high concentrations of oxygen (fio2>40%)
• patient has a neuro-sensorial deficient which prevents reading, writing, or response to simple oral commands (severe deafness, language impairment...)in the absence of a prothesis
• patient has a psychiatric pathology, or chronically consumes alcohol or other mind-altering substance
• patient has had general anesthesia in the last 15 days
• patient under guardianship
• impossible to correctly communicate information to the patient
• absence of efficient contraception for women of childbearing age
• participation in another study within the last 3 months