Low pulse oximetry is the most common adverse events during sedation for upper gastrointestinal endoscopy. The main reason is the glossoptosis after sedation. In present study a new designed nasopharyngeal airway embedded with jet ventilation catheter(WEI NASAL JET) will be utilized in order to reduce the hypoxia. At the same time the safety will be evaluated.

Inclusion Criteria:

• patients undergoing upper gastrointestinal endoscopy
• age over 18 years old
• Signed informed consent form

Exclusion Criteria:

• a blood coagulation dysfunction or have a tendency of nose bleeding
• a clear diagnosis of heart disease (heart failure, angina, myocardial infarction, arrhythmia, etc.)
• a clear diagnosis of lung disease (asthma, chronic obstructive pulmonary disease, pulmonary embolism, pulmonary edema, lung cancer)
• pregnant
• liver disease
• kidney disease
• increase in intracranial pressure
• emergency operation
• multiple trauma
• American Society of Anesthesiologists (ASA) Physical Status classification above IV
• with mouth, nose and throat infection