The unexpandable lung.

Artificial pneumothorax is generally regarded as a reversible procedure, and usually i t is. Comparatively little attention has been directed however, to the fact that when it is stopped, very seldom does the lung fully re-expand. Pinner, Leiner and ZavodD remark that the term "re-expansion" is a misnomer. Often the affected portion of the lung remains permanently collapsed, and the portion of the hemithorax thus vacated is filled variously, with fluid, by compensatory emphysema of the same or of the opposite lung, by elevation of the diaphragm, mediastinal shift or retraction of the chest wall. In all of these instances, the pleural space is obliterated, or else there is left a "dead space" between the two layers of the pleura, and the lung is said to be unexpandable. This complication is recognized now more frequently than before, but we still do not know how often i t occurs. Farber,' on the basis of an admittedly limited series, estimates that about 5 per cent of lungs successfully collapsed by pneumothorax cannot be made to re-expand. This paper does not represent a statistical study; it is a report of a few cases to emphasize the importance of the clinical problem and to point to the fact that artificial pneumothorax is not always a "temporary" treatment. When a lung fails to re-expand,2 generally i t is because of any one or any combination of three factors: bronchial obstruction, massive pulmonary fibrosis and thickened visceral pleura. Bronchial obstruction may be caused by external pressure but usually i t means stenosis secondary to tuberculous endobronchitis.' Distal to the bronchostenosis, whatever the cause, stasis and accumulation of septic products and absorption of the entrapped air produce progressive atelectasis of the affected portion of the lung, and it is incapable of re-expanding? Only too often empyema occurs as a complication of bronchial stenosis. Massive pulmonary fibrosis may arise independently of bronchial obstruction by healing of large tuberculous areas. This