Aspects of chronic airflow obstruction.

This report questions several commonly used definitions and commonly accepted concepts. It suggest that the term, "chronic airflow obstructions," should replace the terms, "chronic obstructive pulmonary disease," "chronic obstructive lung disease," or "chronic airway obstruction," because it is flow that is obstructed. It is suggested the term, "chronic mucous hypersecretion," be used, rather than "chronic bronchitis," and that the latter be avoided. Chronic bronchitis should not be equated with narrowing of the airway and emphysema with loss of elastic recoil. Chronic bronchitis, emphysema, and lesions of the small airways probably occur together more frequently than chance will allow because of a common etiologic agent, tobacco smoke. Chronic mucous hypersecretion without other airway or parenchymal lesions seldom produces airflow obstruction and does not impair prognosis significantly. Central airways are important in chronic airflow obstruction. It is time that someone found out what is happening in subjects with abnormal results on tests of the function of small airways. The definition of "destruction" as it occurs in emphysema is deceptive, and loss of recoil and emphysema may be separate conditions. The dysfunction that occurs in emphysematous lungs is due mainly to associated airway lesions and may perhaps be due in part to the site and nature of emphysematous lesions (as opposed to loss of elastic recoil).