Supplemental oxygen users with pulmonary fibrosis perceive greater dyspnea than oxygen non-users

Mengshu Cao; Frederick S. Wamboldt; Kevin K. Brown; Jonathon Hickman; Amy L. Olson; Joshua J. Solomon; Jeffrey J. Swigris

doi:10.4081/mrm.2015.354

Supplemental oxygen users with pulmonary fibrosis perceive greater dyspnea than oxygen non-users

Authors

Mengshu Cao Interstitial Lung Disease Program, Department of Medicine, National Jewish Health, Denver, CO
Frederick S. Wamboldt Division of Pulmonary, Critical Care, Sleep and Behavioral Medicine, Department of Medicine, National Jewish Health, Denver, CO
Kevin K. Brown Interstitial Lung Disease Program, Department of Medicine, National Jewish Health, Denver, CO
Jonathon Hickman Department of Internal Medicine, Saint Joseph Hospital, Denver, CO
Amy L. Olson Interstitial Lung Disease Program, Department of Medicine, National Jewish Health, Denver, CO
Joshua J. Solomon Interstitial Lung Disease Program, Department of Medicine, National Jewish Health, Denver, CO
Jeffrey J. Swigris Interstitial Lung Disease Program, Department of Medicine, National Jewish Health, Denver, CO

DOI: https://doi.org/10.4081/mrm.2015.354

Keywords:

Interstitial lung disease, Pulmonary fibrosis, Dyspnea, Supplemental oxygen, 6-min walk test

Abstract

Background: Exertional dyspnea is a hallmark symptom of fibrosing interstitial lung disease (fILD), and oxygen (O2) desaturation is common among patients with fILD. Supplemental O2 is prescribed to maintain normoxia and alleviate dyspnea. We sought to better understand the associations between O2 and dyspnea in fILD during the 6-min walk test (6MWT).

Methods: 1326 fILD patients compose the sample group. Borg dyspnea and other 6MWT variables were compared between subjects who performed the test without (non-users) versus with O2 (users).

Results: There were 812 users and 514 non-users; users were older, more likely to have smoked, had greater body mass index, and had more severe fILD. Despite a similar 6-min SpO2, users perceived greater dyspnea than non-users (Borg 3.9 ± 2.0 vs 2.9 ± 1.7, p < 0.0001). Whether subjects became hypoxemic (6-min SpO2 < 89 %) or not during the walk, the results were the same: users perceived greater dyspnea than non-users (hypoxemic: users 3.5 ± 2.1 vs non-users 2.7 ± 1.8, p < 0.0001; non-hypoxemic: users 3.4 ± 1.9 vs non-users 2.4 ± 1.6, p < 0.0001). Among subjects who did not desaturate (SpO2 drop < 4 %), users walked a shorter distance (944.9 ± 367.0 vs 1385.3 ± 322.4 feet, p < 0.0001) but perceived greater dyspnea than non-users (3.3 ± 1.6 vs 2.3 ± 1.7, p = 0.005). No combination of potentially influential predictor variables entered in multivariate models explained more than 11 % of the variance in dyspnea ratings.

Conclusion: Dyspnea is a complex perception, and in patients with fILD, O2 may lessen, but does not resolve, it. Further research is needed to clarify why fILD patients who use O2 perceive greater levels of dyspnea with activity than O2 non-users.