Nitrous Oxide for Analgesia During Nasogastric Tube Placement in Young Children

Inclusion Criteria: * Child from 3 months to 3 years old. * Admission to the Pediatric Emergency Department * Medical prescription for the insertion of a nasogastric tube. * Child with gastroenteritis and / or bronchiolitis and / or food intolerance with mild to moderate dehydration * Parental presence and parental consent Exclusion Criteria: * Vital emergency. * Refusal of parents. * Refusal of parents to be filmed * Child already included in the study or in course of participation in another study. * Tube placement performed by a medical student or nursing student. * Patient requiring 100% oxygen ventilation. * No social security. * Child with a mental handicap or known retardation * History of child intolerance to Nitrous oxide ( excessive sedation or respiratory depression during previous use) * Child with head trauma in the previous 3 days Premature discontinuation of study participation : * Parents' request to stop participating in the study. * Insertion of the nasogastric tube is not possible