inclusion criteria: - validated covid19 disease in case history - hypoxemia (po2 < 55 mmhg) under room air conditions (rest or during exercise) or spo2 <88% during exercise - already established long-term oxygen therapy or given indication for a long-term oxygen therapy

inclusion criteria: - validated covid19 disease in case history - hypoxemia (po2 < 55 mmhg) under room air conditions (rest or during exercise) or spo2 <88% during exercise - already established long-term oxygen therapy or given indication for a long-term oxygen therapy