Gastroscopy is a commonly used, direct, and reliable method for screening and diagnosing digestive tract diseases. However, as an invasive examination, it can cause adverse reactions such as pain, nausea, vomiting, and choking cough in patients. Compared with ordinary gastroscopy, painless gastroscopy offers higher comfort and satisfaction for patients and greater convenience for endoscopists during operation. The most common complication of painless gastroscopy diagnosis and treatment is hypoxia. High-flow nasal cannulala (HFNC) provides a higher oxygen concentration and flow rate than an ordinary nasal catheter. It has the functions of heating and humidifying, which can relieve the pressure on the nasal mucosa cilia, keep the airway unobstructed and moist, and reduce the risk of epistaxis. Due to changes in airway anatomical structures such as fat accumulation in the head and neck and hyperplasia of oropharyngeal soft tissues, obese patients are more prone to hypoxia during gastroscopy under sedation. Therefore, HFNC is often used to reduce the occurrence of hypoxia. The nasopharyngeal airway (NPA) is used to maintain the patency of the upper respiratory tract and is suitable for patients with spontaneous breathing but partial obstruction of the upper respiratory tract. It is worth exploring how effective the combination of HFNC and NPA is in improving hypoxemia in obese patients during sedation.