Hypoxia is the most common adverse event during propofol sedation for gastrointestinal endoscopy. The STOP-BANG questionnaire is a widely used, simple assessment tool for screening obstructive sleep apnea (OSA) risk. A STOP-Bang score ≥5 indicates high-risk OSA patients who are more prone to hypoxia during sedated endoscopy. Our team's preliminary clinical research found that High-Flow Nasal Cannula (HFNC) may reduce hypoxemia risk, but there are limited dedicated studies focusing specifically on high-risk OSA patients, with controversial results. This study aims to investigate whether HFNC can reduce the incidence of hypoxia during sedated gastrointestinal endoscopy in high-risk obstructive sleep apnea patients.