For performing transnasal humidified rapid insufflation ventilatory exchange (THRIVE), jaw-thrust maneuver have to maintain to make sure the airway open and the CO2 clearance during apnoea. The objective of present study is to prove that nasopharyngeal airway facilitate THRIVE and no need jaw-thrust maneuver and maintain the similar PO2 and PCO2 during apnoea.

Inclusion Criteria:

• Signed informed consent.
• Undergoing surgery with general anaesthesia.
• Adult, >18 years old.
• American Society of Anesthesiology classification I-II.

Exclusion Criteria:

• Coagulation disorders or a tendency of nose bleeding
• An episode/exacerbation of congestive heart failure (CHF) that requires a change in medication, diet or hospitalization from any cause in the last 6 months
• Severe aortic stenosis or mitral stenosis;
• Cardiac surgery involving thoracotomy (e.g., coronary artery bypass graft (CABG), valve replacement surgery) in the last 6 months;
• Acute myocardial infarction in the last 6 months;
• Acute arrhythmia (including both tachycardia and bradycardia) with hemodynamic instability;
• Diagnosed COPD or current other acute or chronic lung disease requiring supplemental chronic or intermittent oxygen therapy);
• Increased intracranial pressure;
• ASA >II;
• Mouth, nose, or throat infection;
• Fever, defined as core body temperature > 37.5°C;
• Pregnancy, breastfeeding or positive pregnancy test;
• Emergency procedure.
• Patient with known or suspected difficult airway