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Exertional hypoxemia is more severe in fibrotic interstitial lung disease than in COPD
Author(s) -
Du Plessis Jean P.,
Fernandes Senan,
Jamal Rakin,
Camp Pat,
Johannson Kerri,
Schaeffer Michele,
Wilcox Pearce G.,
Guenette Jordan A.,
Ryerson Christopher J.
Publication year - 2018
Publication title -
respirology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 85
eISSN - 1440-1843
pISSN - 1323-7799
DOI - 10.1111/resp.13226
Subject(s) - medicine , copd , dlco , interstitial lung disease , hypoxemia , cardiology , pulmonary rehabilitation , idiopathic pulmonary fibrosis , oxygen therapy , oxygen saturation , lung volumes , lung , physical therapy , diffusing capacity , oxygen , lung function , chemistry , organic chemistry
ABSTRACT Background and objective Despite its clinical and prognostic significance, few studies have evaluated the severity of exertional oxygen desaturation in fibrotic interstitial lung disease (ILD). Our objectives were to identify clinical and physiological variables that predict the extent of exertional oxygen desaturation in fibrotic ILD and to quantify the severity of desaturation compared to chronic obstructive pulmonary disease (COPD). Methods This retrospective study compared the results of 6‐min walk test (6MWT) performed while breathing room air in fibrotic ILD patients and COPD patients eligible for pulmonary rehabilitation. Outcomes included the oxygen saturation (SpO 2 ) nadir and the change in SpO 2 from rest during a 6MWT. Predictor variables were identified on unadjusted analysis, followed by multivariate analysis to identify independent predictors of desaturation. Results The study included 134 patients with fibrotic ILD and 274 patients with COPD. The ILD and COPD cohorts had similar age, sex, frequency of major comorbidities, walk distance, baseline SpO 2 and baseline Borg dyspnoea scores. DL CO was the strongest predictor of desaturation in both cohorts. Compared to patients with COPD, ILD patients had significantly lower SpO 2 nadir values (88.1 ± 6.4 vs 91.0 ± 4.6) and greater decrease in SpO 2 from baseline (7.4 ± 5.2 vs 4.5 ± 3.7) after adjusting for demographic features and pulmonary physiology ( P < 0.0005), with greater between‐group differences at lower DL CO values. Conclusion Patients with fibrotic ILD have greater oxygen desaturation during 6MWT compared to patients with COPD when adjusting for demographic features and pulmonary physiology. These findings suggest the need for disease‐specific studies to evaluate the potential utility of ambulatory oxygen in fibrotic ILD.