OBSTRUCTIVE OR SCARRING DISEASES
Obstructive respiratory disorders are characterized by narrowing of the bronchi (air
passages) of the lungs. They include asthma, chronic
bronchitis, emphysema,
bronchiectasis, and cystic fibrosis. The bronchial narrowing produces obstruction to the flow of air into and particularly out of the lungs. In the case of asthma the size of the airways is reduced because of inflammation of the airway lining (mucosa) and by spasm of the muscles in the airway walls.
Chronic bronchitis and emphysema are nearly always the result of long-term cigarette smoking. Chronic bronchitis refers to chronic cough and production of phlegm, caused by inflammation of the airway mucosa. Emphysema is the destruction of lung tissue with the formation of cystlike spaces called bullae in the lungs. Trapping of air in bullae and destruction of gas-exchange tissue of the lung makes breathing inefficient and difficult for the person with this disease. Emphysema and chronic bronchitis are treated with inhaled and oral medications to increase airflow and reduce shortness of breath. Surgical procedures designed to remove large bullae are warranted in selected individuals to reduce symptoms of shortness of breath and exercise intolerance.
Scarring diseases, including bronchiectasis, are characterized by chronic scarring of the bronchi from an earlier bout of pneumonia or other illness. Individuals with this disorder have a chronic cough and produce a lot of phlegm.
Cystic fibrosis (CF) is a genetic disease leading to bronchiectasis, chronic infection, and scarring of the lung. It affects the secretion of the glands that produce mucus, sweat, saliva, and digestive juices. In the lungs the mucus becomes very thick, blocking up the gas exchange surfaces and making the person with CF prone to lung infections.
Pneumoconioses are scarring diseases of the lung tissue (pulmonary fibrosis) caused by inhalation of nonallergenic inorganic dusts such as silica, which causes silicosis; coal dust, causing black lung, or coal worker's pneumoconiosis; and asbestos fibers, which cause asbestosis. The result of these disorders is impairment of lung function and progressive disability. There is currently no treatment for these disorders. Protection against inhalation of the dust can prevent pneumoconioses from developing.