Fig. 2.

Oxygen Therapies - Non-invasive ventilation provides ventilator support without an endotracheal tube, using an oronasal (A) mask or modified snorkel (total face) (B) mask or a helmet (C). High Flow Nasal Cannula through Prongs or Nasal Cannulas (D) delivers accurate FiO₂, PEEP and tidal volume at a flow equal to or greater than the patient's inspiratory flow demand. Nasal oxygen is delivered at a flow rate of up to 60 L/min. It is heated to the body's need and saturated to full moisture. Invasive mechanical ventilation (E) uses a tracheal tube inserted into the trachea under general anesthesia. The tube is then secured to the face or neck and connected to a ventilator. In patients with hypoxemic acute respiratory failure, such as COVID-19 patients, intubation and invasive mechanical ventilation are used after failure of non-invasive methods. Adapted from Ref. [34].