As a pilot study, the investigators will recruit up to 20 patients within a 12 month period scheduled for elective microlaryngeal surgery and high frequency jet ventilation. Standard monitoring and standard conduct of anaesthesia will be carried out: induction of general anaesthesia, insertion of a narrow catheter into the trachea and insertion of laryngeal mask airway. In addition, the study device (HFNC) will be placed into the entrance of the patient's nostrils. After removal of the laryngeal mask, HFNC oxygenation will commence. A surgical suspension laryngoscope will be inserted for microlaryngeal surgery (standard technique). The investigators will measure the adequacy of gas exchange, during of HFNC oxygenation and complications (cardiovascular, airway and respiratory). Data will be stored on a secure REDCap (Research Electronic Data Capture) system.