Protective ventilation decreased morbidity and mortality in adults' patients and is now a standard of care in intensive care unit and in anesthesiology. In children, there is no evidence in the literature to recommend protective ventilation during anaesthesia. Moreover the ratio of instrumental dead space to tidal volume is higher in children than in adults. Therefore, it is difficult to propose an "optimal" tidal volume for all children. The objective of this study is to evaluate the use of alveolar ventilation (estimated by the volumetric capnography) in children under anesthesia. The hypothesis is that in children, alveolar ventilation reported to ideal body weight is a constant to maintain normocarbia, unlike the tidal volume.

Inclusion Criteria:

• Children aged < 12 and
• Weight between 5 and 40kg
• General anesthesia
• Non-opposition of parents or legal guardians

Exclusion Criteria:

• History of bronchodysplasia or laryngo tracheo malacia, cyanotic heart disease or neuromuscular disease
• Airleaks > 10%
• Bronchospasm during anesthesia

Children under general anaesthesia