Pleurisy (Pleuritis), inflammation of the pleura, the membrane which lines the chest, and also covers the lungs. Pleurisy has been recognized and described as a distinct disease from the earliest times, but practically, before the discoveries of Laennec, it was impossible in many cases to distinguish it from pneumonia. The disease, though rare in old age and in early infancy, is confined to no period of life. Prolonged exposure to cold, external violence, and the existence of tubercles in the lungs may be considered its most frequent causes, though in many instances we are unable to trace it to any particular source. The disease may be either acute or chronic. Acute pleurisy ordinarily begins with a chill, which is soon followed by a sharp pain limited to a single spot, and most commonly seated just below the breast on one side. This pain is often very intense, preventing the patient from taking a full breath, and increased by motion, by pressure, and by cough. It lasts a variable length of time, but gradually subsides as effusion takes place. In not a few instances pain is altogether absent. Cough comes on early, is short and commonly dry, and adds greatly to the distress of the patient.

The respiration early in the disease is short and difficult; as the pain subsides the patient breathes more easily; but when effusion to any amount has taken place, any exertion'rarely fails to render the breathing abnormally frequent. Before effusion takes place the patient commonly lies on the back or the sound side, rarely on the affected side; after it the patient generally lies on the back or on the affected side. Fever is commonly present, the skin is hot and dry, the pulse frequent and sometimes hard, the urine scanty and high-colored. In the first stage of acute pleurisy the respiratory murmur is feeble, and the breathing, as before observed, is short and jerking; very early in the disease friction sounds, either slight and grazing or rubbing, may be heard; these depend on the exudation of plastic lymph. During this period the percussion sound remains almost or entirely unaffected. Sometimes the disease stops short at this point. "Where effusion takes place, the most depending part of the chest on the affected side gradually becomes dull on percussion; as this dulness increases the respiratory murmur is lost on auscultation, or is replaced by a distant bronchial breathing; the friction sound is lost over the part occupied by the fluid, though it may sometimes still be heard above it.

The vibratory thrill that is felt by. the hand applied to the walls of the chest when a patient speaks is abolished over the seat of the effusion. When the effusion is moderate in amount, the height to which it rises posteriorly can very readily be marked out by percussion, and this will be found to vary with the varying position of the patient. At this time, and commonly near the inferior angle of the scapula, a peculiar modification of the voice, sego-phony (Gr. Pleurisy Pleuritis 1300587 , a goat, and Pleurisy Pleuritis 1300588 , voice), can be heard by the ear or stethoscope applied to the walls of the chest while the patient is speaking. It consists of a variety of bronchophony in which the voice acquires a tremulous, cracked character, which has been compared to the bleating of a goat. When the effusion is very great it distends the pleural sac, the lung deprived of air being compressed against the spinal column. The diaphragm is now pushed downward, the intercostal spaces are bulged out, the side is larger by measurement than the opposite one, and is comparatively motionless in respiration. The heart is displaced, and when the effusion is on the left side can sometimes be felt beating to the right of the right nipple. In cases of recovery, as the fluid is absorbed the respiratory murmur and the normal percussion note gradually return from above downward; for a long time, however, and sometimes permanently, owing to the thickness of the false membranes formed from the plastic lymph effused, the respiratory murmur is feeble and the percussion sound dull at the lower part of the side.

In some cases the side is restored to its natural form; in others it becomes retracted, the shoulder being drawn down, the ribs approximated, the spine curved, and the whole side rendered smaller and sunken. - When acute pleurisy occurs in a strong and healthy young adult, general bloodletting may be required; but in a majority of cases local bloodletting by means of cups and leeches is all that is necessary, and this has a remarkable influence over the pleuritic pain. After bloodletting diuretics may be administered, and of these the best are the acetate and bi-tartrate of potassa, digitalis, and squill. Where the disease is obstinate it may be advisable to give mercury, but it should be given in small doses and stopped immediately upon the slightest signs of ptyalism. When the acute symptoms have subsided, the application of a succession of blisters to the affected side has a decided influence in promoting the absorption of the effusion; or instead of blisters, resort may be had to bromide and iodide of potassium, or a course of sulphur. The diet should be low, and the patient where the effusion is extensive or increasing should abstain as much as possible from fluids.

Perforation of the thorax has been recommended, and it would appear from numerous trials that, performed carefully, the operation is attended with little risk; but in acute pleurisy it should only be resorted to in those rare cases in which the amount or rapid increase of the effusion threatens the patient with immediate suffocation. In such cases care should be taken by the use of a proper instrument to prevent the admission of air into the thorax. - In chronic pleurisy the effusion remains for a long time stationary, and either gives rise to an acute febrile excitement or to one of a hectic character. It may be the result of an acute pleurisy, it may come on in patients debilitated by previous disease, or it may be complicated with the tubercular diathesis, the last being the case in the majority of instances. The effused fluid may be either serum mixed with flocculent lymph or pus. When the strength of the patient is good, a gentle mercurial course with diuretics and the use of flying blisters or iodu-retted liniments will often remove the effusion. Bromide and iodide of potassium are often all that is necessary. If the patient be broken down, tonics and cod-liver oil with iodine may be advisable, while ioduretted liniments are freely employed.

In young persons, particularly in children, if there be no tubercular complication, the operation for empyema is generally successful. - In some persons pleurisy gives rise to extensive effusion without causing any symptoms to attract the attention of the patient. Sometimes a person may be seen with one pleural cavity distended with fluid, and yet pursuing his ordinary occupations, scarcely conscious that he is ill. This is latent pleurisy, the treatment of which is the same as for acute, except that it should be less active.