Table 1 Inclusion/exclusion criteria

1) Aged ≥65 and <80 years

1) Coagulation disorders or a tendency of nose bleeding

2) Scheduled to undergo gastrointestinal endoscopy procedure with sedation

2) An episode/exacerbation of congestive heart failure that requires a change in medication, diet, or hospitalization from any cause in the past 6 months

3) Signed the informed consent form

3) Severe aortic stenosis or mitral stenosis

4) American Society of Anesthesiologists (ASA) classification I-II

4) Cardiac surgery involving thoracotomy (e.g., coronary artery bypass graft, valve replacement surgery) in the past 6 months

5) Acute myocardial infarction in the past 6 months

6) Acute arrhythmia (including any tachycardia or bradycardia) with fluid of hemodynamics instability

7) Diagnosed with chronic obstructive pulmonary disease or current other acute or chronic lung disease requiring supplemental chronic or intermittent oxygen therapy

8) Preexisting bradycardia (heart rate <50/min), or hypoxia (SaO₂ < 90%)

9) Need supplemental oxygen because of preexisting diseases

10) Emergency procedure or surgery

11) Multiple trauma

12) Upper respiratory tract infection

13) Allergy to propofol or tape and adhesives