Table 1.

Types of oxygen therapy and ventilatory support and their potential in treating breathlessness in IPF patients.

	Mechanism of action	Evidence	Disadvantages
AOT LTOT	- Improvement in neuro-mechanical uncoupling (74) - Lower neural respiratory drive (74) - Stimulation of upper airway receptors by gas flow (55) - Improved cardiovascular function and pulmonary hemodynamics (75) - Delayed lactate accumulation (76)	In patients with ILD and exertional hypoxemia: - Improvement of total K-BILD score and its subdomains i.e., breathlessness, activity and chest symptoms during routine activities of daily living (31) - Increase in cycle endurance time (28, 29) - Increase in CPET peak work capacity (28) - Increase in CPET peak oxygen uptake (28) - Reduction of Borg dyspnea score at the end of cycle exercise test and at the iso-time (29, 30) - Improved leg muscle oxygenation and reduction of fatigue (77) Dyspnea was not assessed in LTOT studies in ILD patients (28)	Portable oxygen systems • expensive, • may be hard to carry and difficult to use, • deliver limited amount of oxygen, • attract unwanted attention when used outside home Stationary oxygen systems • Risk of tripping over the tubing • Fire and burning hazard • Activity limited to the immediate surroundings of the oxygen system
HFNC	- Pharyngeal dead space washout (35) - Reduction of work of breathing (36, 37) - Matching patient's high inspiratory demand (35) - EPAP generation (up to 7.4 cm H2O) (78) - Lung compliance increase (35) - Upper airway resistance reduction (35) - Reduction of metabolic work associated with gas conditioning i.e., warming and humidifying (35) - Improvement of mucocilliary clearance (35)	Direct evidence i.e., based on studies involving ILD patients: - Increase in cycle endurance time (40–42) Indirect evidence: - Improvement of dyspnea in advanced cancer patients compared to oxygen therapy (38) - Improvement of dyspnea when used alongside LTOT in COPD patients compared to LTOT alone (43)	• Expensive • Only for stationary use • Requires high flow O2 source/sources (79) • Generates fair degree of noise (44)
NIPPV	- EPAP effects (80): *Lung compliance increase *Alveolar recruitment *Upper airway resistance reduction - IPAP effects (80): *Unloading of respiratory muscles *Tidal volume increase	Indirect evidence: - Improvement of dyspnea in advanced cancer patients compared to oxygen therapy (38), especially those with hypercapnic respiratory failure (46)	• Most expensive solution among discussed • Less comfortable than HFNC (38) • Doesn't allow for food intake and impedes speaking • Risk of face ulcerations secondary to tight-fitting masks • Patient might need help putting on the mask

6MWT, six-minute walking test; AOT, ambulatory oxygen therapy; CPET, cardiopulmonary exercise testing; EPAP, expiratory positive airway pressure; HFNC, high glow nasal cannulae; ILD, interstitial lung disease; IPAP, inspiratory positive airway pressure; IPF, idiopathic pulmonary fibrosis; K-BILD, King's Brief ILD questionnaire; LTOT, long term oxygen treatment; NIPPV, non-invasive positive pressure ventilation.