Common causes include impaired respiratory drive (eg, due to toxins, CNS disease), and airflow obstruction (eg, due to asthma, COPD [chronic obstructive pulmonary disease]
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Forced expiratory volume in 1 second (FEV 1.0 ) is the most commonly used index of airflow obstruction.
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Pulmonary function test measurements are required for the diagnosis of obstructive lung disease and for assessment of the severity of disease.
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