THE RESPIRATORY SYSTEM 81 



Bronchitis 



The principal inflammatory disturbance of the 

 bronchial tubes is of a catarrhal nature, at least in the 

 beginning. Catarrhal bronchitis may be either acute or 

 chronic. 



Etiology. Undue exposure to inclement weather is 

 one of the principal causes of bronchitis. Inhalation of 

 dust-laden air is also an important causative factor of 

 inflammation of the bronchial tubes. Infection is in 

 many instances an auxiliary of other causes and the 

 Bacilli necrophorous and pyocyaneus are many times the 

 primary causes of bronchial catarrh. This condition may 

 be associated with other diseases, such as swine plague 

 or hog cholera. 



Chronic bronchial catarrh results from the action of 

 the same causative factors that produce acute catarrh, 

 but the irritants are usually less intense and act for a 

 longer time. 



Lesions. There is congestion of the affected mucosa, 

 which later becomes covered with mucous or with a 

 mucopurulent discharge. In extreme cases the discharge 

 may be tinged with blood and become purulent. When 

 the disease process involves the capillary bronchial tubes 

 there is usually more or less of emphysema, due to obstruc- 

 tion of the tubes with exudate which prevents the escape 

 of air from the air cells. There may be areas of 

 atelectasis which project beyond the surface of the lung 

 and are of a darker color than the lung. 



Chronic bronchial catarrh is characterized by the 

 presence of mucous, purulent, or even caseous material 

 in the bronchial tubes, and by fibrous proliferation in 

 the submucosa which may result in an attenuation of 

 the mucosa. Dilatation or bronchiectasis is a common 

 lesion, particularly in the dependent parts of the lung, in 

 chronic catarrhal bronchitis. In long-standing cases 

 there may be peribronchitis, evidenced by fibrous pro- 

 liferation around the bronchial tubes, which may extend 

 into the pulmonary tissue. 



