GCS- Glasgow coma scale , RR- Respiratory rate, Vt -- Tidal volume, PSV- Pressure support ventilation, pCO2 -- partial pressure of carbon dioxide , pO2- partial pressure of oxygen, SpO2 -- Saturation of oxygen in periphery capillary blood , FiO2 -- fraction of oxygen in inspired air, NIV- Non invasive ventilation, Pf ratio --ratio of arterial oxygen partial pressure to fractional inspired oxygen