PLEURISY AND DROPSY OF THE CHEST.
Pleurisy (Pleuritis) is the name given to inflammation of the serous membrane that in closes each lung as by a sac. • The membrane, as described on p. :344, is formed of a double layer, one fold being closely applied over the lung, and the other over the chest wall, a slight space, in which a small quantity of serous fluid is usually present, being between the two. Now inflammation affecting this membrane is of the same nature as inflammation occurring any where else, and its features have been stated on p. 327. The blood-vessels of the membrane, for it is richly supplied with them, are congested, and materials pass out of them into the ear rounding tissues, so that the membrane becomes thickened. A considerable quantity of material is poured out on the surfaces of the pleura, and separates into a fibrinous or coagulable portion and a fluid—serous—part. The fibrinous ma terial is deposited on the surface, and the fluid escapes into the small space between the two folds of the membrane. The surfaces of the folds, which are opposed to one another and ought to glide smoothly on one another with the move ments of breathing, are roughened in conse quence of the deposit. The movement, instead of being smooth and noiseless, is accompanied by considerable friction, which occasions a fine rubbing sound that a practised ear can detect by listening with the ear to the chest. If a large quantity of fluid is poured into the space, it will separate the two layers of the pleura, and the friction, with its accompanying sound, will cease. Whether much or little fluid ac cumulates in the pleural sac depends on the nature of the case. In some instances only a few ounces are present, in others the quantity is many pints. So much fluid must make ac commodation for itself between the lung and the wall of the chest. It may make sonie room by forcing out the wall of the chest and making the chest perceptibly fuller on the affected side. But the ribs do not yield very much or readily, and the fluid will make more space by displac ing the organs of the chest and crushing the lung together as much as possible. For ex ample, if the pleurisy be on the left side, the heart may be pushed over to the right side by the accumulating serum. The pressure of the fluid on the lung may be sufficient to expel the air from its air-cells, and compress the substance of the lung so that it is squeezed into a com pact mass, and the air-cells no longer exist.
In some severe cases of this kind the pres sure on the lung has been so great that, after death, on the affected side only a small fleshy mass, pushed up into a corner of the chest, re mained as evidence of the existence of a lung, the cavity being completely occupied by fluid. Dropsy of the chest, or hydrothorax (Greek, hudor, water, and thorax, the chest), is the term applied when the accumulation of fluid is con siderable. Of course, in the chest the fluid will seek the lowest level, and thus, at first, it will occupy the bottom of the cavity, surrounding the lung, compressing to some extent the ex treme parts of the lung ; but, as it increases in amount, it will rise, squeezing the air out of the lung as it ascends.
In the ordinary run of cases so much fluid is not poured out as to cause complete collapse of the lung. The inflammation passes away. Processes of repair set in. The poured-out fluid begins to be absorbed, partly by blood-vessels, partly by lymphatics (p. 278), and, as it dimin ishes, the lung, released from the pressure, slowly expands. In time the fluid is all re moved, the two folds of membrane glide on one another again, and, their surfaces being rough, friction is reproduced. Generally also the roughened surfaces become adherent to one another, either in parts or throughout their whole extent, and the pleural cavity ceases to exist. This is practically complete recovery. The case, however, may not end so favourably as this. The lung may have been so much compressed that when the fluid is .removed it cannot expand, or can only expand to a slight extent. There being nothing to fill the space it should occupy, the wall of the chest is sucked in, the organs in the chest are pulled over to that side, and the person acquires a peculiar way of holding himself, his shoulder dropping, and his whole body leaning to the affected side. In another way the end may be Unfortunate. Matter may be formed in the cavity of the pleura, and an abscess result, which may in time discharge itself into the lung, the matter being spat up, or may point and open to the outside, an open channel leading from the outside to the cavity. This condition is called empyaerna (Greek, en, within, and peon., matter).