Eur Respir Rev. 2017 Feb 21;26(143).

Bonini M, Fiorenzano G.

Interstitial lung diseases (ILDs) represent a heterogeneous group of pathologies
characterised by alveolar and interstitial damage, pulmonary inflammation
(usually associated with fibrosis), decreased lung function and impaired gas
exchange, which can be attributed to either a known or an unknown aetiology.
Dyspnoea is one of the most common and disabling symptoms in patients with ILD,
significantly impacting quality of life. The mechanisms causing dyspnoea are
complex and not yet fully understood. However, it is recognised that dyspnoea
occurs when there is an imbalance between the central respiratory efferent drive
and the response of the respiratory musculature. The respiratory derangement
observed in ILD patients at rest is even more evident during exercise.
Pathophysiological mechanisms responsible for exertional dyspnoea and reduced
exercise tolerance include altered respiratory mechanics, impaired gas exchange,
cardiovascular abnormalities and peripheral muscle dysfunction.This review
describes the respiratory physiology of ILD, both at rest and during exercise,
and aims to provide comprehensive and updated evidence on the clinical utility of
the cardiopulmonary exercise test in the assessment and management of these
pathological entities. In addition, the role of exercise training and pulmonary
rehabilitation programmes in the ILD population is addressed.