inclusion criteria: * more than 18 years (adult, older adult) * confirmed covid-19 (positive sars-cov-2 rt-pcr at nasopharyngeal swab) * acute respiratory failure with 100 \< pao2:fio2\< 300 mmhg * spontaneous ventilation with standard oxygen supply or high flow humidified oxygen * written informed consent of the patient

inclusion criteria: * more than 18 years (adult, older adult) * confirmed covid-19 (positive sars-cov-2 rt-pcr at nasopharyngeal swab) * acute respiratory failure with 100 \< pao2:fio2\< 300 mmhg * spontaneous ventilation with standard oxygen supply or high flow humidified oxygen * written informed consent of the patient

inclusion criteria: - more than 18 years (adult, older adult) - confirmed covid-19 (positive sars-cov-2 rt-pcr at nasopharyngeal swab) - acute respiratory failure with 100 < pao2:fio2< 300 mmhg - spontaneous ventilation with standard oxygen supply or high flow humidified oxygen - written informed consent of the patient

inclusion criteria: - more than 18 years (adult, older adult) - confirmed covid-19 (positive sars-cov-2 rt-pcr at nasopharyngeal swab) - acute respiratory failure with 100 < pao2:fio2< 300 mmhg - spontaneous ventilation with standard oxygen supply or high flow humidified oxygen - written informed consent of the patient