Upper gastrointestinal endoscopy is a commonly performed diagnostic and therapeutic procedure in children, allowing evaluation of the esophagus, stomach, and duodenum, as well as interventions such as biopsy, foreign body removal, and polypectomy. Sedation is routinely used, often at greater depths than for standard examinations. Due to anatomical and physiological differences, including smaller airway diameter, higher oxygen consumption, and lower functional residual capacity, pediatric patients are at higher risk of airway obstruction, hypoxemia, and hypoventilation compared to adults. The passage of the endoscope through the mouth further limits airway access and increases the risk of desaturation. Oxygenation during pediatric endoscopy is typically supported using nasal cannulas, high-flow systems, or procedural oxygen masks (POM™). This pilot randomized study aims to compare POM™ and high-flow nasal cannula in preventing hypoxemia during sedated pediatric upper gastrointestinal endoscopy, contributing evidence for safer sedation and airway management practices in children.