inclusion criteria: non- intubated patient diagnosed with moderate to severe pneumonia (confirmed by chest x-ray and officially reported) as secondary to covid-19 with one more symptom such as: respiratory rate at ≥ 20 breath.min-1. oxygen saturation (sato2) ≤ 90% at rest on room air. arterial partial pressure of oxygen (pao2) ≤ 80 mmhg at resting. pao2/fio2 ratio or p/f (is the ratio between the arterial partial pressure of oxygen and the percentage of oxygen supplied) < 300mmhg.

inclusion criteria: non- intubated patient diagnosed with moderate to severe pneumonia (confirmed by chest x-ray and officially reported) as secondary to covid-19 with one more symptom such as: respiratory rate at ≥ 20 breath.min-1. oxygen saturation (sato2) ≤ 90% at rest on room air. arterial partial pressure of oxygen (pao2) ≤ 80 mmhg at resting. pao2/fio2 ratio or p/f (is the ratio between the arterial partial pressure of oxygen and the percentage of oxygen supplied) < 300mmhg.

inclusion criteria: - non- intubated patient diagnosed with moderate to severe pneumonia (confirmed by chest x-ray and officially reported) as secondary to covid-19 with one more symptom such as: 1. respiratory rate at ≥ 20 breath.min-1. 2. oxygen saturation (sato2) ≤ 90% at rest on room air. 3. arterial partial pressure of oxygen (pao2) ≤ 80 mmhg at resting. 4. pao2/fio2 ratio or p/f (is the ratio between the arterial partial pressure of oxygen and the percentage of oxygen supplied) < 300mmhg.

inclusion criteria: - non- intubated patient diagnosed with moderate to severe pneumonia (confirmed by chest x-ray and officially reported) as secondary to covid-19 with one more symptom such as: 1. respiratory rate at ≥ 20 breath.min-1. 2. oxygen saturation (sato2) ≤ 90% at rest on room air. 3. arterial partial pressure of oxygen (pao2) ≤ 80 mmhg at resting. 4. pao2/fio2 ratio or p/f (is the ratio between the arterial partial pressure of oxygen and the percentage of oxygen supplied) < 300mmhg.