is a condition in which respiratory function is inadequate to meet the body's needs when increased physical activity places extra demands on it. Insufficiency occurs as a result of progressive degenerative changes in alveolar structure and capillary tissues in the pulmonary bed, as, for example, in chronic airflow limitation and pulmonary fibrosis. Treatment is essentially supportive and symptomatic. If the condition is not successfully managed it may progress to respiratory failure.
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