1. Physiological underpinnings of exertional dyspnoea in mild fibrosing interstitial lung disease.
- Author
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Smyth, Reginald M., Neder, J. Alberto, James, Matthew D., Vincent, Sandra G., Milne, Kathryn M., Marillier, Mathieu, de-Torres, Juan P., Moran-Mendoza, Onofre, O'Donnell, Denis E., and Phillips, Devin B.
- Subjects
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LUNG volume measurements , *DYSPNEA , *IDIOPATHIC pulmonary fibrosis , *EXERCISE tests , *PULMONARY fibrosis , *INCREMENTAL motion control , *INTERSTITIAL lung diseases - Abstract
The functional disturbances driving "out-of-proportion" dyspnoea in patients with fibrosing interstitial lung disease (f -ILD) showing only mild restrictive abnormalities remain poorly understood. Eighteen patients (10 with idiopathic pulmonary fibrosis) showing preserved spirometry and mildly reduced total lung capacity (≥70% predicted) and 18 controls underwent an incremental cardiopulmonary exercise test with measurements of operating lung volumes and Borg dyspnoea scores. Patients' lower exercise tolerance was associated with higher ventilation (V̇ E)/carbon dioxide (V̇CO 2) compared with controls (V̇ E /V̇CO 2 nadir=35 ± 3 versus 29 ± 2; p < 0.001). Patients showed higher tidal volume/inspiratory capacity and lower inspiratory reserve volume at a given exercise intensity, reporting higher dyspnoea scores as a function of both work rate and V̇ E. Steeper dyspnoea-work rate slopes were associated with lower lung diffusing capacity, higher V̇ E /V̇CO 2 , and lower peak O 2 uptake (p < 0.05). Heightened ventilatory demands in the setting of progressively lower capacity for tidal volume expansion on exertion largely explain higher-than-expected dyspnoea in f -ILD patients with largely preserved dynamic and "static" lung volumes at rest. • The physiological abnormalities driving "out-of-proportion" dyspnea in mild f -ILD remain unclear. • Despite normal spirometry and total lung capacity typically above 70% predicted, patients showed moderate impairment in DL CO • Exertional dyspnea was related to heightened ventilatory demands and progressively lower capacity for tidal volume expansion • Exertional dyspnea and exercise intolerance were associated with lower DL CO , excess ventilation, and inspiratory constraints • These findings can causally link mild f -ILD to "out-of-proportion" dyspnoea, exposing potential therapeutic targets [ABSTRACT FROM AUTHOR]
- Published
- 2023
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