High-flow Nasal Cannula Oxygenation in Sedated Endoscopy for High-risk Obstructive Sleep Apnea Patients

Inclusion Criteria: * Age ≥18 years. * STOP-Bang score ≥5. * Scheduled for sedated gastrointestinal endoscopy (gastroscopy, colonoscopy, or combined gastroscopy + colonoscopy). * The estimated duration of the procedure does not exceed 45 minutes. * Patients have signed the informed consent form. Exclusion Criteria: * Coagulation disorders or bleeding tendency (e.g., oral/nasal bleeding risk, mucosal injury, space-occupying obstructions). * Active upper respiratory tract infection (oral, nasal, or pharyngeal), or fever (core temperature \>37.5°C). * Chronic obstructive pulmonary disease or other acute/chronic pulmonary diseases requiring long-term or intermittent oxygen therapy, or preoperative SpO₂ ≤ 92% on room air. * Severe organ dysfunction, including: Cardiac insufficiency (\<4 METs), Severe renal insufficiency (requiring dialysis), Diagnosed severe hepatic insufficiency, Increased intracranial pressure, ASA physical status ≥ IV. * Confirmed pregnancy or current breastfeeding. * Known allergy to sedatives (e.g., propofol) or medical adhesives. * Multiple traumatic injuries. * Current participation in another clinical trial. * Other conditions deemed unsuitable by the investigator.