This study aims to compare the effect of the use of supraglottic jet oxygenation and ventilation (SJOV) with high-flow nasal oxygen therapy (HFNO) on reducing the rate of hypoxia during gastrointestinal endoscopic procedures in deeply sedated patients at high altitudes.

The participants will be randomly allocated to either SJOV or HFNO in a 1:1 ratio using block randomization with variable block sizes of four or six randomized. In the HFNO group, oxygen supplementation is delivered at 35 liters min-1 with a fraction of inspired oxygen (FiO2) of 100%. In the SJOV group, SJOV is conducted using a Wei nasal jet tube (WNJ, Well Lead Medical Co. Ltd, Guangzhou, China) which is connected to a manual jet ventilator (Well Lead Medical Co. Ltd, Guangzhou, China) via its jet port. The initial settings of SJOV were as follows: driving pressure (DP) 15 psi; respiratory rate (RR) 20 bpm; inspiratory-to-expiratory (I/E) ratio 1:2, and gas supply, 100% oxygen.

Inclusion Criteria:

1. 18 years or older;
2. underwent routine gastrointestinal endoscopy under procedural sedation;
3. consented to participate in this trial.

Exclusion Criteria:

1. infection of the upper airway;
2. anatomical abnormalities of the face, nose, and upper airway;
3. coagulopathies;
4. anticipated or known difficult airway;
5. known allergy against propofol, soybeans, and egg;
6. absence from the high-altitude environment during the past 3 months.