Nitrous Oxide for Analgesia During Nasogastric Tube Placement in Young Children

Since nitrous oxide/oxygen mixture is effective to reduce pain and anxiety induced by various painful procedures in children, the investigators hypothesized that its inhalation would reduce pain during nasogastric tube placement in young children. The purpose of this study is to evaluate the analgesic efficacy of 50%/50% nitrous/oxide mixture in reducing pain induced by nasogastric tube insertion in children aged 3 months to 3 years in the pediatric emergency department.

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 to be filmed or to have their child 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. * Child with new-onset neurological abnormalities or other altered states of consciousness. * Child with intracranial hypertension. * Child with pneumothorax * Child having received in the last 3 months prior to inclusion an ophthalmic gas ( SF6, C3F8, C2F6) * Child with known vitamin B12 deficiency or unsubstituted folic acid. * Child who has had a diving accident. * Child with abdominal gas distension abdominal * Child with gas embolism * Child with pulmonary emphysema Premature discontinuation of study participation : * Parents' request to stop participating in the study. * Insertion of the nasogastric tube is not possible