Optimization of oxygenation during endoscopy of the upper gastrointestinal system (GIS) in children is a mandatory routine. Desaturation during the procedure can lead to interruptions in the procedure, increasing morbidity and mortality. In a clinical trial involving 12,030 esophagogastroduodenoscopy and colonoscopy procedures, the incidence of adverse events was reported to be 4.8 %, and the most common complications, in descending order of frequency, were persistent desaturation, airway obstruction, cough and laryngospasm [1]. In another recent clinical series, desaturation and increased oxygen delivery were reported as the most common adverse events [2]. In a meta-analysis of approximately 14000 cases of procedural sedation in children, airway complications included hypoxia, apnea, laryngospasm, and the need for tracheal intubation [3].

In cases where spontaneous breathing is preserved, various oxygenetion methods are used to maintain oxygenation. Low-flow oxygen support can be delivered via a convantional nasal cannula for endoscopic procedures. Other techniques include high-flow nasal cannula oxygen (HFNO), non-invasive ventilation, or Mapleson circuit oxygenation [4].

A high-flow oxygen delivery system is increasingly used in anesthesia practice because it prolongs the apneic time without desaturation [5]. These systems allow the maximum flow rate to be increased to 120 L/min [6]. As the heated and humidified air-oxygen mixture is delivered to the patient, it provides better patient comfort. The main mechanisms of action include reduction of work of breathing, flushing of anatomical dead space, reduction of nasopharyngeal resistance, and metabolic demand [7]. In addition, HFNO can reduce airway obstruction and increase end-expiratory lung volume by creating positive pressure in the nasopharynx and thoracic cavity [8].

In this prospective observational cohort study, our primary aim was to compare the effect of HFNO administration with conventional nasal cannula oxygenation (NCO) in reducing the incidence of hypoxia in pediatric patients undergoing procedural sedation for upper GI endoscopy. The secondary objective of our study was to compare the effects of HFNO administration and NCO administration on perioperative vital parameters and postoperative recovery parameters.