Though most authors state without reservation that inflammatory pleural effusion is distinguishable from hydro thorax by its unilateral character, the preliminary symptoms, and the fever, some—as Leube, Pepper, and Osler—have very properly insisted that hydrothorax may be unilateral and unattended by ex ternal (edema; and, on the other hand, that inflammatory pleural effusion may be latent; that is, unaccompanied by the usual symptoms. A knowledge of the possibility of hydrothorax of this char acter is of clinical importance, though, even with the full recognition of this possibility, difficulty may occasionally arise in determining whether an effusion is dropsical or inflammatory.
In some cases a unilateral hydro thorax is chronic in character, and the fluid, after repeated tapping, increases in specific gravity. In such instances it may be that a secondary inflammatory exudation has been added to the drop sical effusion. Alfred Stengel (Univ. of Penna. Med. Bull., June, 1901).
The physical signs are those of pleurisy with effusion, but somewhat modified, on account of the absence of fibrinous layers on the pleural surfaces. There is less distension of the side. Vocal fremitus is absent. The breathing may be bron chial on account of collapse of the air vesicles; it is usually faint. On light percussion the note is dull. There is no friction rub. Frequently there is a crepi tant rale over the upper part of the ef fusion and above it, owing partly to ex pansion of collapsed vesicles and partly to oedema of the lung-tissue.
Etiology.—Hydrothorax occurs in a variety of conditions from obstruction to the venous and lymph outflow. The great majority of cases occur as a part of general dropsy, especially in cardiac failure, emphysema, and renal disease. In both the latter cardiac failure with anmmia plays the chief part in the cau sation of pleural dropsy. Mediastinal tumor, by pressing on veins, may also give rise to it.
The amount of exudation into the various cavities varies greatly and for this no satisfactory explanation can be offered. In heart disease the dropsy is often limited to one pleural cavity; in renal disease both are usually affected. An intrathoracic tumor may cause dropsy on one or both sides, from pressure on the azygos veins.
Morbid Anatomy.—The effusion is a clear straw-colored fluid, rich in albumin usually,—richer than the dropsical fluids of the pericardium, peritoneum, or sub cutaneous tissues. This has been attrib
uted to the suction-action of the pleural cavity excited by the retractile energy of the lung.
In recent exudation the pleura is nor mal in appearance, but after a time it loses its glistening appearance on ac count of the formation on its surface of a fibrous film which can be peeled off. This is probably due to slight inflam mation from prolonged contact of the fluid. The lymphatics of the pleura may form a visibly-dilated net-work. The lung is more or less collapsed, and in cases of long standing requires consid erable pressure to expand it.
Treatment.—The treatment should be directed chiefly to the cause. If we can restore the equilibrium in the circulation in the cardiac cases the dropsy will soon disappear. When the presence of fluid can be demonstrated, it should usually be aspirated, as its removal relieves the heart; or at least sufficiently to enable it to recover compensation, especially if, at the same time, the right ventricle be relieved by venesection. Digitalis and similar remedies then become effective, although previously their administration was without benefit.
I-Immothorax.
Symptoms.—The symptoms are those of hmmorrhage, and if the escape is rapid and large there will be dyspncea in proportion to the pressure on the lung.
The symptoms are those of pleural ef fusion without fever or friction. The percussion-note is absolutely flat if co agulation in even a thin layer takes place.
The diagnosis is based on the signs of loss of blood, accompanied with those of rapid accumulation of fluid in the pleu ral cavity.
Etiology.—Hmorrhage into the pleu ral cavity may occur from a variety of causes. In traumatic cases there may be rupture of an intercostal or mammary artery, or laceration of the lung. Rupt ure of an aneurism of the aorta occurs not infrequently into the pleural cavity. Occasionally rupture of an aneurism of the internal mammary occurs, and in rare eases there is an intrathoracic rupture of a vein into the pleural cavity. Rarely bleeding takes place from rupture of a pulmonary infarct, and of a phthisical cavity into the pleura at the same time that a vessel is lacerated. Bleeding may also occur in scurvy and in purpura.