Inclusion Criteria:  Age category between 3 to 12 years Candidate for lower abdominal elective surgery under general anesthesia No obstruction in the nasal pathway No deformity and fractures in facial No acute or chronic lung disease  Exclusion Criteria:  Impossibility of airway oropharyngeal ventilation Impossibility of ventilation of the anatomical facial mask with neck extension Dissatisfaction with participating in the study.