HYDROTHORAX. 285 



as a matter of convenience, and in compliance with ancient custom, 

 that I have included it in the list of disorders of the pleura. 



Hydrothorax, caused by augmented pressure within the veins of 

 the pleura, is one of the more formidable accidents occurring in diseases 

 of the lung which (as we have shown in a previous chapter) obstruct 

 the action of the right side of the heart, and produce venous engorge- 

 ment of the aortic circulation. It occurs with equal frequence in cer- 

 tain diseases of the heart, namely, derangement of its valves and 

 degeneration of its muscular substance, which, as we shall show by- 

 and-by, also impede the outflow of the blood from the right side of the 

 heart, and from the veins of the aortic system. 



Hydrothorax, dependent upon diminution of the amount of albu- 

 men in the serum of the blood, whose pathogeny is somewhat obscure, 

 as we shall show while treating of Bright's disease, is one of the ac- 

 companiments of grave cachectic conditions, and especially of inflam- 

 mations occurring in chronic degeneration of the kidney with albumi- 

 nuria, in malignant malarious disease, and in dysentery of long standing. 



Whether hydrothorax be a consequence of venous engorgement, 

 or of a morbid state of the blood, it is usually but one of the symptoms 

 of a general dropsy. When arising from the former condition, it 

 sometimes precedes the effusion into other cavities, whereas it almost 

 always appears at a late period when due to the latter. 



ANATOMICAL APPEARANCES. Hydrothorax is almost always dou- 

 ble, but one pleura sometimes contains more liquid than the other. 

 Its amount varies from a few ounces to many pounds. It usually is 

 movable, but is sometimes incapsulated by old adhesions. The trans- 

 udation contained hi the pleura is a clear, yellowish liquid, consisting 

 of water, albumen, and the salts of the serum of the blood. It is easily 

 distinguishable from a pleuritic effusion, by the absence of the fibrinous 

 coagula and inflammatory changes in the pleural surfaces. The latter 

 have lost their polished appearance, and have a milky opacity, and 

 both they and the subserous tissue are slightly swollen by serous infil- 

 tration. When the effusion is very large, the lungs, unless they are 

 held down by old adhesions, are driven up against the spinal column, 

 large portions of them being in a state of compression. 



SYMPTOMS AND COURSE. From the most ancient times down to 

 the beginning of the present century, the symptoms and course of 

 water on the chest, as an independent disease, have not only been 

 described with great fulness and accuracy, but, in many instances, the 

 diagnosis has been confirmed by post-mortem dissection. This was be- 

 cause the symptoms ascribed to the disease by the ancients apply to 

 the class of affections of the lungs and heart which ultimately results 

 in dropsical transudations of all kinds, and in effusions into the pleura. 



