paroxysmal nature, to which the- term cardiac asthma has been
applied. Similarly, to a form of dyspnoea met with occasionally
as a manifestation of uraemia in chronic Bright's disease the
term of renal asthma has been given.
Pleurisy, or inflammation of the pleura, is a very common affection, and is met with under different forms. In many p|em, sy instances we have simply the pouring out, over a greater or less area of the surface of the pleura, of a fibrinous exudation which may become absorbed or undergo organisation, a certain amount of thickening of the pleura, and adhesion's of the two layers resulting. Such cases form the group known as cases of dry pleurisy. In other instances a greater or lesser amount of serous exudation takes place into one or other pleural cavity, forming the cases of serous pleuritic effusion. In others the exudation into the pleural cavity is purulent, giving rise to the condition known as empyema or purulent pleuritic effusion. The occurrence of dry pleurisy is probably very frequent, and leads to small pleural adhesion's which cause little or no inconvenience. In post-mortem examinations of persons who have died from various diseases it is common to find such pleural adhesion's present, although they have never been suspected during life. Pleurisy in one or other of the above forms may come on in a person apparently in good health (idiopathic pleurisy), or it may follow a fracture of the ribs or other injury to the chest. It is not uncommonly secondary to some other disease; thus it is almost a constant accompaniment of acute lobar pneumonia. In such cases the effusion is most commonly a simple fibrinous one, which with the subsidence of the primary disease is in great part absorbed. In other cases of pneumonia we get a certain amount of serous effusion into the pleura; and sometimes, especially in children, the pneumonia is followed by the development of an empyema. Pleurisy with effusion is also frequently a complication of valvular heart disease and dilatation of the heart, and in such cases is often associated with the formation of superficial pulmonary infarcts. It is also seen in many other diseases of the lungs. For instance, in chronic pulmonary phthisis pleuritic adhesion's over various parts of the lungs are the rule; and we also frequently get serous effusion into the pleura as a complication of the various forms of pulmonary tuberculosis. Purulent effusion is less common in phthisis, but it is the rule where the pleura is perforated by the necrosis of a tuberculous focus in the lung and the establishment of a communication between the pleura and a tuberculous cavity and the bronchial tubes (pyopneumrmolhorax), a combination in which there is both air and pus in the pleural cavity. Secondary pleurisy is also seen in an extension of the disease from neighbouring parts, as from peritonitis, sub-diaphragmatic abscess, and suppuration in the liver or spleen. As a secondary disease, pleurisy is also known in the course of various forms of nephritis, rheumatism, and the acute specific diseases.
Cases formerly classed as idiopathic pleurisy are now known to be caused by certain micro-organisms. These vary in relation to the character of the effusion. The most frequent is the tubercle bacillus, which is generally present in sero-fibrinous effusions. In this case the pleurisy is really secondary to a possibly unrecognized tuberculous infection either of the lung or pleura. In purulent effusions the pneumococcus may occur as a pure infection, or the streptococcus pyogenes or the staphylococcus may be present. Mixed infections occur in 21% of purulent effusions, and varieties of other organisms, such as the influenza bacillus, the typhoid bacillus, the Klebs-Lofiler bacillus and the colon bacillus, have been occasionally found. There are at least five types of pulmonary emphysema; (1) hypertrophic, idiopathic or large-lunged emphysema; (2) senile or small-lunged emphysema; (3) compensatory emphysema; (4) acute vesicular emphysema; (5) interstitial or interlobular emphysema. Two points are usually admitted: that emphysema appears only in lungs that are congenitally weak, and that the exciting cause is increased intravesicular tension. When one or more lobules are cut off from the working part of the lung the neighbouring vesicles become distended. Should the plugging of the lobule remain permanent, typical emphysema results. This happens in illnesses inducing violent respiratory efforts, such as chronic bronchitis, whooping cough and asthma. In large-lunged emphysema the lung is excessively large, and does not collapse on opening the chest wall. Microscopically two lesions are notable. The septa between the vesicles are atrophied, many have disappeared and the vesicles have coalesced; the loss in lung tissue diminishes the vascular field of the lung and tends to imperfect aeration, whence the dyspnoea. The elastic tissue of the lung is also lost. In small lunged emphysema there is a condition of senile atrophy. The lung is smaller than normal, and the intravesicular septa are destroyed. In this case the primary cause is atrophy of the bronchi, and increased air pressure is not a factor. Compensatory emphysema is that which develops in a portion of a lung in which the other portion is the seat of a lesion, such as pneumonia. Occasionally it is merely physiological, but sometimes here too the septa undergo atrophic changes. Acute vesicular emphysema is hardly a pathological variety, and is really rapid distension coming on during an attack of asthma or angina pectoris. The variety is temporary only. Interstitial emphysema is characterized by the presence of air in the inter stitial connective tissue of the lung. It is usually due to rupturl of the air vesicles during paroxysms of coughing. (T. H *; H. L. H.)
(5) SURGERY or THE RESPIRATORY SYSTEM
About the middle of the 19th century, Manuel Garcia demonstrated the working of the vocal cords in the living subject, by placing a flat mirror of about the size of a shilling at the back oi the mouth, and throwing strong light on to it from a concave mirror fixed upon the observer's forehead. By the use of a laryngoscope and a cocaine spray the most irritable throat can now be made tolerant of the presence of the small mirror, and thus the medical man is enabled to make a prolonged and thorough examination of the interior of the larynx and even to perform delicate operations upon it. Foreign bodies which have become caught in the larynx can thus be seen and extracted, and small growths can be satisfactorily removed even from the vocal cords themselves.
A foreign body in the air-passages may be impacted above the vocal cords, and the prompt thrusting down of a finger may dislodge it and save the person from death by suffocation. If there is doubt as to the site of the impaction, and the symptoms are urgent (as is likely to be the case) immediate laryngotomy should be done. In this operation a tube is introduced through the crevice which can easily be felt in the middle line of the neck, between the thyroid and cricoid cartilages. The procedure is easily and quickly accomplished. It is, moreover, often resorted to when the surgeon is about to perform some extensive operation in the mouth which must needs be accompanied by free hemorrhage. Laryngotomy having been done, and the pharynx having been plugged with gauze, the air passages can be kept free of blood during the whole operation. If the foreign body be such a thing as a button, cherry-stone, sugar-plum or coin, it may at once set up alarming symptoms of spasmodic suffocation. But when the first alarm has quieted down, the attacks are likely to be only occasional, as when the article, drawn up with the expired air, comes in contact with the under aspect of the vocal cords. It may be that in a violent fmt of coughing it will be expelled, but, if not, the surgeon must be at hand ready to perform tracheotomy when the urgency of the symptoms demands it. Tracheotomy is the making of an opening into the trachea, the air-tube below the larynx. It is unsafe to leave a child with a foreign body loose in its windpipe, on account of the risk of sudden and fatal asphyxia. Possibly the X-rays may show its exact position and give help in its removal. But, in any case, the safest thing will be to perform tracheotomy and to leave the edges of the opening into the windpipe wide asunder, so that the object may be coughed out -the nurse being on guard all the while. The operation of tracheotomy is sometimes urgently called for in the case in
