inclusion criteria (all of the following): 1. age ≥ 18 years 2. sars-cov-2 found in the upper or lower respiratory tract by pcr during the current disease episode 3. peripheral oxygen saturation (spo2) \< 92 % despite conventional low-flow oxygen therapy of at least 6 l /min for at least 15 min 4. a decision to initiate hfnc or helmet cpap by the attending ward physician 5. the patient has given written informed consent to participate. exclusion criteria (any of the following): 1. need for direct admission to the intensive care unit for mechanical ventilation 2. unconsciousness or drowsiness 3. pneumothorax 4. carbon dioxide pressure (pco2) \> 6 kpa in venous blood gas (vbg) 5. underlying chronic obstructive pulmonary disease stage iii-iv 6. a decision not to participate 7. inability to comprehend the study content and give informed consent

inclusion criteria (all of the following): 1. age ≥ 18 years 2. sars-cov-2 found in the upper or lower respiratory tract by pcr during the current disease episode 3. peripheral oxygen saturation (spo2) \< 92 % despite conventional low-flow oxygen therapy of at least 6 l /min for at least 15 min 4. a decision to initiate hfnc or helmet cpap by the attending ward physician 5. the patient has given written informed consent to participate. exclusion criteria (any of the following): 1. need for direct admission to the intensive care unit for mechanical ventilation 2. unconsciousness or drowsiness 3. pneumothorax 4. carbon dioxide pressure (pco2) \> 6 kpa in venous blood gas (vbg) 5. underlying chronic obstructive pulmonary disease stage iii-iv 6. a decision not to participate 7. inability to comprehend the study content and give informed consent

inclusion criteria (all of the following): age ≥ 18 years sars-cov-2 found in the upper or lower respiratory tract by pcr during the current disease episode peripheral oxygen saturation (spo2) < 92 % despite conventional low-flow oxygen therapy of at least 6 l /min for at least 15 min a decision to initiate hfnc or helmet cpap by the attending ward physician the patient has given written informed consent to participate. exclusion criteria (any of the following): need for direct admission to the intensive care unit for mechanical ventilation unconsciousness or drowsiness pneumothorax carbon dioxide pressure (pco2) > 6 kpa in venous blood gas (vbg) underlying chronic obstructive pulmonary disease stage iii-iv a decision not to participate inability to comprehend the study content and give informed consent

inclusion criteria (all of the following): age ≥ 18 years sars-cov-2 found in the upper or lower respiratory tract by pcr during the current disease episode peripheral oxygen saturation (spo2) < 92 % despite conventional low-flow oxygen therapy of at least 6 l /min for at least 15 min a decision to initiate hfnc or helmet cpap by the attending ward physician the patient has given written informed consent to participate. exclusion criteria (any of the following): need for direct admission to the intensive care unit for mechanical ventilation unconsciousness or drowsiness pneumothorax carbon dioxide pressure (pco2) > 6 kpa in venous blood gas (vbg) underlying chronic obstructive pulmonary disease stage iii-iv a decision not to participate inability to comprehend the study content and give informed consent

inclusion criteria (all of the following): 1. age ≥ 18 years 2. sars-cov-2 found in the upper or lower respiratory tract by pcr during the current disease episode 3. peripheral oxygen saturation (spo2) < 92 % despite conventional low-flow oxygen therapy of at least 6 l /min for at least 15 min 4. a decision to initiate hfnc or helmet cpap by the attending ward physician 5. the patient has given written informed consent to participate. exclusion criteria (any of the following): 1. need for direct admission to the intensive care unit for mechanical ventilation 2. unconsciousness or drowsiness 3. pneumothorax 4. carbon dioxide pressure (pco2) > 6 kpa in venous blood gas (vbg) 5. underlying chronic obstructive pulmonary disease stage iii-iv 6. a decision not to participate 7. inability to comprehend the study content and give informed consent

inclusion criteria (all of the following): 1. age ≥ 18 years 2. sars-cov-2 found in the upper or lower respiratory tract by pcr during the current disease episode 3. peripheral oxygen saturation (spo2) < 92 % despite conventional low-flow oxygen therapy of at least 6 l /min for at least 15 min 4. a decision to initiate hfnc or helmet cpap by the attending ward physician 5. the patient has given written informed consent to participate. exclusion criteria (any of the following): 1. need for direct admission to the intensive care unit for mechanical ventilation 2. unconsciousness or drowsiness 3. pneumothorax 4. carbon dioxide pressure (pco2) > 6 kpa in venous blood gas (vbg) 5. underlying chronic obstructive pulmonary disease stage iii-iv 6. a decision not to participate 7. inability to comprehend the study content and give informed consent