Lung mucus: a clinician's view

Respiratory mucus represents the products derived from secretion of the submucosal glands and the goblet cells. Accumulation of mucus in the airway tree may be caused by an increased volume of mucus produced, and also by decreased clearance due to defects in the ciliary clearance apparatus. Hypersecretion of mucus contributes to the morbidity of airway diseases by predisposing patients to respiratory infections, and contributing to airflow obstruction and to patients' discomfort. There is a significant association between chronic production of mucus and an increased risk of mortality. Also the degree of airway obstruction is related to the physical properties of the sputum. Observation of chronic bronchitic sputum can reveal important clinical information concerning the type and level of the inflammatory process, the physical properties of the material, the extent of bronchial mucosal damage, and the identification of pathogenic microorganisms that may be present. The management of mucous hypersecretion can be undertaken in two main ways: firstly, improved clearance by physical methods; and, secondly, by pharmacological methods.