High-flow Nasal Oxygen Therapy for Advanced Endoscopy in High-risk Patients.

The investigated intervention is the application of HFNO throughout a high-risk upper GI-endoscopy. Concentration of oxygen is 100%. Prior to induction, flow rate is set to 20 l/min and increased to 30 l/min if tolerated by the patient. After induction of anesthesia, flow rate is increased to 60 l/min and maintained throughout the anesthesia.