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Spontaneous Pneumothorax

1938; Radiological Society of North America; Volume: 30; Issue: 4 Linguagem: Inglês

10.1148/30.4.471

1527-1315

David Ehrlich, Alexander Schomer,

Medical Imaging and Pathology Studies

Introduction SPONTANEOUS pneumothorax has long been associated with pulmonary tuberculosis, particularly as a complication of the more advanced active stages of that disease. The first to describe pneumothorax was Itard, in 1803, and Lænnec is said to have been the first to have diagnosed it and to have fully described the physical findings upon which a diagnosis could be made. Prior to the advent of x-ray examination and fluoroscopy and before the use of this diagnostic aid had become universally prevalent, there was an absence of case reports on spontaneous pneumothorax. In the last two decades, case reports of non-tuberculous spontaneous pneumothorax began to appear in greater numbers. Of special interest is the increasing number of cases occurring in otherwise apparently healthy individuals without any antecedent history or physical stigmata of tuberculosis or evidence of any other pathologic condition of the lung. These are the so-called idiopathic or essential types of spontaneous pneumothorax. In reviewing the literature on this subject it is apparent that many observers use the term “spontaneous” in its narrower sense, namely, that in which there is no evident internal or external cause for the pneumothorax. “Spontaneous pneumothorax” embraces all cases whether primary or secondary to pathologic changes, in contradistinction to the artificial or induced pneumothorax. “Idiopathic or essential spontaneous pneumothorax” is the term used in cases in which there is no evident cause for the condition. Anatomy The so-called “lung unit” is the “lobule” (Fig. 1). Air enters the lobule through a respiratory bronchiole which is a branch of a larger bronchiole. The respiratory bronchiole leads into several alveolar ducts, each of which branches out into from three to six atria. Each atrium leads into an alveolar sac, which finally ends in the terminal alveoli. Numerous alveoli communicate with one another. However, there are also scattered alveoli along the walls of the respiratory bronchioles. These latter alveoli have a more direct communication with the main bronchi. The visceral layer of the pleura is very thin and firmly attached to the lung. It is composed of an outer mesothelial layer of flat cells which rests on a thin layer of fibrous tissue, beneath which is a subserous layer of fibrous tissue. Subjacent to this layer are the pulmonary alveoli which, with their blood, nerve, and air supply, compose the lung lobule. The pleural cavity is the space between the visceral and parietal pleura. Normally it is negligible during a deep inspiration, as the visceral layer glides over the parietal layer. During expiration the space is actual, and varies from one-half to one inch in extent. The lungs are kept distended by virtue of the negative pressure normally maintained in the pleural cavities.