inclusion criteria: * age ≥ 18 years * confirmed or suspected covid-19 patient (by rt-pcr) having severe pneumonia and hypoxemia (spo2 ≤90%) who did not respond to standard oxygen therapy (non-rebreather mask on 15l/min at 100% fio2).

inclusion criteria: * age ≥ 18 years * confirmed or suspected covid-19 patient (by rt-pcr) having severe pneumonia and hypoxemia (spo2 ≤90%) who did not respond to standard oxygen therapy (non-rebreather mask on 15l/min at 100% fio2).

inclusion criteria: - age ≥ 18 years - confirmed or suspected covid-19 patient (by rt-pcr) having severe pneumonia and hypoxemia (spo2 ≤90%) who did not respond to standard oxygen therapy (non-rebreather mask on 15l/min at 100% fio2).

inclusion criteria: - age ≥ 18 years - confirmed or suspected covid-19 patient (by rt-pcr) having severe pneumonia and hypoxemia (spo2 ≤90%) who did not respond to standard oxygen therapy (non-rebreather mask on 15l/min at 100% fio2).