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

This non-blinded, randomized controlled trial compares two study groups, the interventional and control group, to investigate whether HFNO-treatment reduces the risk of hypoxemia during peri-interventional high-risk upper GI endoscopy. The randomization schema is developed by an unblinded statistician using SAS (Statistical system) and uploaded to the REDCap randomization module, enabling delegated team members to generate sequential allocations for enrolled subjects. Patients assigned to the control group will receive supplemental oxygen throughout anesthesia in accordance with hospital guidelines, either using a standard nasal cannula or procedural oxygen mask (POM). The choice of supplemental oxygen delivery, as well as oxygen flow rates, are at the discretion of the anesthesia provider. Post-anesthesia, patients will be transferred to the recovery room with either the standard nasal cannula or procedural oxygen mask at a flow rate determined by the anesthesia provider. Patients assigned to the intervention group will receive humidified oxygen throughout anesthesia in order to assess the effect of HFNO. High-flow nasal cannula (Fisher \& Paykel Optiflow) are connected prior to induction of anesthesia, allowing for different flow rates and oxygen concentration to be administered according to the study protocol. The oxygen concentration of the delivered gas for the trial is 100%. Prior to induction, flow rate will be set to 20 liters per minute and increased to 30 liters per minute if tolerated by the patient. After induction of anesthesia, flow rate will be increased to 60 liters per minute and maintained throughout anesthesia. After anesthesia, the high-flow nasal cannula will be exchanged to a standard nasal cannula and the patient will be transferred to the recovery room at which point the flow rate will be determined by the anesthesia provider. The decision to discontinue the intervention of the study is entirely at the discretion of the attending anesthesiologist. Alternative means of supplemental oxygen delivery, such as nasal cannula or oxygen mask, may be considered by the attending anesthesiologist. If the intervention is discontinued, the rationale for the decision is documented for later analysis.