Inclusion Criteria:  Patient over 18 years Patient in operating room for scheduled surgery Patient receiving general anaesthesia with orotracheal intubation Patient given written consent after information Patient covered by social security or equivalent regimen  Exclusion Criteria:  Patient undergoing thoracic and spinal surgery, due to the presence of dressings that interfere with measurements, Patient who has undergone intracerebral surgery because of possible communication difficulties upon awakening, Patients with a body mass index (BMI) > 50 (measurements not possible) Pregnant or breastfeeding patient, Patient contraindicated to the use of a thoracic electroimpedancemetry technique: dressings, wounds, presence of a pacemaker, defibrillator or any other active implant. Patient deprived of liberty by a judicial or administrative decision or patient subject to a legal protection measure (guardianship, curatorship...) Patient in a period of exclusion from another research protocol Any other reason that, in the opinion of the investigator, could interfere with the evaluation of study objectives