HFNO Combined With NPA Reduces Hypoxia During Sedated Gastrointestinal Endoscopy In Obese Patients

Inclusion Criteria: 1. Patients receiving selective combined upper intestinal and lower intestinal endoscopy procedure under deep sedation. 2. Age ranging from 19 to 80, both male and female 3. Obese patients，BMI ≥ 28kg/m\^2 4. ASA I\~III 5. Patients should clearly understand and voluntarily participate in the study, with signed informed consent. Exclusion Criteria: 1. Patients with acute respiratory infection in the last 2 weeks 2. Patients with nasal congestion, epistaxis, recent nasal trauma, recent nasal surgery 3. hypoxia, defined as oxygen saturation measured by pulse oximetry (SpO2) ≤ 95% before preoxygenation. 4. Common advanced gastrointestinal endoscopy procedures meeting eligibility criteria included cholangiopancreatography, endoscopic ultrasound procedures, endoscopic mucosal resection and endoscopic retrograde cholangiopancreatography (ERCP) procedures. 5. coagulation disorders or platelets \< 100\*10\^9/L 6. Have serious heart diseases such as severe arrhythmia, heart failure, Adams Stokes Disease, unstable angina pectoris, myocardial infarction in the last 6 months, history of tachycardia / bradycardia requiring medical treatment, third degree atrioventricular block or QTC interval ≥ 450ms (corrected according to fridericia's formula), or exercise tolerance \< 4mets 7. Allergy to eggs, soy products, opioids and other drugs, propofol, etc. 8. Participated in other clinical trials as a subject within 3 months 9. Patients with brain injury, possible convulsion, myoclonus, intracranial hypertension, cerebral aneurysm, cerebrovascular accident history, schizophrenia, intellectual disability, mania, psychosis, long-term use of psychotropic drugs, drug addiction, cognitive dysfunction history, etc. 10. Emergency procedure 11. Pregnant or breast-feeding women 12. Patients having procedures with planned tracheal intubation or laryngeal mask 13. Investigator considers the patients are inappropriate to participate in this trial