ABSTRACT

Pleural effusions, for instance, can be secondary to a variety of intrathoracic, intraabdominal, or systemic disorders. A clear understanding of the anatomy and physiology of the pleural space as well as of the pathophysiology involved in disease processes such as pneumothoraces, pleural effusions, and empyemas greatly facilitates the selection of appropriate therapies. The visceral pleura is devoid of somatic innervation and is thus insensitive. In contrast, the parietal pleura is innervated through a rich network of somatic, sympathetic, and parasympathetic fibers. Pleural fluid is constantly secreted, mostly by filtration from the microvessels of the parietal pleura. Most individuals presenting with a secondary spontaneous pneumothorax are males aged 45 or more and nearly all have an underlying pulmonary disorder, usually chronic obstructive pulmonary disease (COPD). Several reports have described the association of spontaneous pneumothoraces with AIDS. Pleural effusions develop because of a disturbance in the normal mechanisms that move 5–10 L of fluid across the pleural space every day.