VII. Diseases of the Pleura.
Definition:—An inflammation of common occurrence, involving the parietal and visceral layers of the pleura.
The disease may be acute, subacute or chronic, and it is divided, in its various forms of manifestation, into (1) dry, fibrinous or plastic pleurisy, which is the usual form of acute pleurisy. (2) Sero-fibrinous pleurisy—pleurisy with effusion, usually sub-acute in character. (3) Purulent pleurisy or empyema—suppurative pleurisy—and, (4) adhesive pleurisy—pleuritic adhesion—chronic pleuritis.
Etiology:—The disease occurs in the early part of the winter and in the late winter or early spring, as the exciting cause is cold and sudden temperature changes. Although it occurs at any period of life, it is most common in early middle life, and to the male sex, because of their more frequent exposure. As it follows many forms of acute and infectious disease, its occurrence under these circumstances depends to an extent upon the occurrence of those diseases and upon the causes which induce them.
The cause of the disease is micro-organisms. These may be the pneumococcus—the diplococcus of pneumoma—the various pyogenic organisms, the bacillus tuberculosis, the typhoid bacillus or the specific bacillus of various other diseases. The immediate exciting cause is exposure to cold, traumatism or the presence of other inflammatory disease, either specific or non-specific in character.