Background: Proper adjustment of arterial oxygen saturation (SaO2) during daily activities in patients with interstitial lung disease (ILD) requiring long-term oxygen therapy is challenging. Given the multifactorial nature of the limited exercise tolerance in patients with ILDs, the isolated use of oxygen therapy may not be enough. As demonstrated previously in patients with chronic obstructive pulmonary disease, the use of a noninvasive ventilation (NIV) device combined with oxygen therapy may prevent the falling of oxygen saturation during exercise, due to an improvement of the ventilation-perfusion ratio and a reduction of the respiratory work, thus enhancing exercise tolerance. We sought to assess in patients diagnosed with ILD who are in need of oxygen therapy, the effect of associating an NIV to improve oxygen parameters and the distance covered during the 6 min walking test (6MWT).
Methods: We conducted a prospective observational study in patients with ILDs. After a clinical characterization, we performed a 6MWT in two different situations: using a portable oxygen concentrator with the regular flow used by the patient during their daily life activities and afterwards adding the additional support of a NIV. The oxygen saturation parameters were registered with a portable oximeter.
Results: We included 16 patients with different ILDs who have oxygen therapy prescribed. The use of NIV associated with oxygen therapy in comparison with the use of oxygen therapy alone showed an increase of the average SaO2 [91% (88-93) versus 88% (86-90%); p = 0.0005] and a decrease in the percentage of time with oxygen saturation <90%: 36% (6-56%) versus 58% (36-77%); p < 0.0001. There were no changes in the 6MWT distance: 307 m (222-419 m) versus 316 m (228-425 m); p = 0.10.
Conclusions: In our study the use of a NIV system associated with long-term oxygen therapy during exercise showed beneficial effects, especially improvement of oxygen saturation.The reviews of this paper are available via the supplemental material section.
Keywords: 6-minute walking test; LTOT; interstitial lung diseases; noninvasive ventilation; oxygen therapy.