Table 2 Drawbacks of standard oxygen therapy that limit the effectiveness and tolerance of oxygen delivery [15,16,17,18,19,20,21]
Oxygen is not humidified at low flow: |
 dry nose  dry throat  dry mouth  nasal pain  ocular irritation,  nasal and ocular trauma  discomfort related to the mask  gastric distension  aspiration  global discomfort |
Insufficient heating leads to poor tolerance of oxygen therapy |
Unwarmed and dry gas may cause bronchoconstriction and may decrease pulmonary compliance and conductance |
With low/medium-flow devices, oxygen cannot be delivered at flows greater than 15 L/min, whereas inspiratory flow in patients with respiratory failure varies widely and is considerably higher, between 30 and more than 100 L/min |
Given the difference between the patient’s inspiratory flow and the delivered flow, FiO2 is both variable and often lower than needed |