ARDS: acute respiratory distress syndrome; BMI: body mass index; CRP: C-reactive protein; COPD: chronic obstructive pulmonary disease; GFR: glomerular filtration rate; Hb: haemoglobin; ICU: intensive care unit; LVEF: left ventricular ejection fraction; NIV: non-invasive ventilation; NPS: naso-pharyngeal swab test; NYHA: New York heart association; PCI: percutaneous coronary intervention; PCT: procalcitonin; SpO2: oxygen saturation; WBC: white blood cells.