Exercise pathophysiology and the role of oxygen therapy in idiopathic interstitial pneumonia.

Exercise limitation is a common feature in idiopathic interstitial pneumonia (IIP). There are multiple contributing pathophysiological mechanisms, including ventilatory mechanical limitation, impaired gas exchange, pulmonary vascular insufficiency and peripheral muscle dysfunction. Progressive exertional dyspnoea and functional incapacity impact significantly on quality of life. Exercise-induced desaturation is frequently observed and is predictive of poorer outcomes. Tests to assess the cardiorespiratory system under stress (e.g. cardiopulmonary exercise testing and the 6-min walk test) can provide important physiologic and prognostic information as adjuncts to resting measurements of lung function. Despite many advances in understanding disease mechanisms, therapies to improve exercise capacity, symptom burden and quality of life are lacking. Exercise training and supplemental oxygen are two potential interventions that require closer evaluation in patients with IIP.