Primary Pneumonia

Primary Pneumonia especially attacks vigorous adults, although delicate persons are also liable to this disease, and, indeed, not unfrequently seem decidedly predisposed to it; up to advanced age it is generally lobar, attacking at the least the whole of a lobe, and depositing a plastic, hepatizing product in it. It further occurs in children, and even in newborn infants, presenting in this case several peculiarities; the granular texture of the hepatized lung is generally only indistinctly seen, owing most probably to the density of the organ and the smallness of its cells; moreover the termination in abscess is relatively more frequent in children than in adults, and the lobular form is more frequently met with at this early age, although the simple catarrhal pneumonia is often mistaken for it. It arises in consequence of the influence of a peculiar atmospheric condition which predisposes to inflammation accompanied with abundant plastic exudations, and it may then be excited by many even very trivial causes; and in this point of view a notice of the combinations into which the primary pneumonic process enters is of importance, since they proceed from a common primary cause, namely a peculiar, spontaneous, morbid change in the blood.

One of the constant symptoms is the sympathetic affection of the visceral surface of the pleura of the inflamed lobe, in the form of a thin plastic exudation investing it.

The anomalous condition of the blood which occurs in the pneumonic process, as well as in the other primary exudative processes, is a subject of much importance, since in this affection the change occurs in the most marked form and in the highest degree. In consequence of this circumstance we always find fibrinous coagula in the cavities of the heart as well as in the large vessels and their branches, and not unfrequently in those ramifications of the pulmonary artery which supply the inflamed lobe; they are distinguished by their yellowish and greenish color, by their firmness, by a more or less decided metamorphosis into pus in their interior, by their similarity to the exudations on membranous expansions, and by their being woven among the trabecule of the heart; and their partial coalescence with the endocardium and the inner membrane of the vessels, together with an obvious appearance of a secondary irritation in them, combine to show that they, at least in part, originated during life.

Pneumonia, if we except the pleurisy which coexists with it, very frequently occurs as an independent disease (an exudative process) upon an extensive surface of mucous membrane, and may become more widely diffused in the lobar form, although it may, on the other hand, often be combined with similar processes upon other structures. Of these processes croup in the final ramifications of the bronchi is far the most common (Lobstein), and is indicated by the presence of creamy, purulent dissolving coagula in them. In children it occurs in combination with croup on the tracheal and other mucous membranes, and with exudations on serous membranes, as pleuritis, pericarditis, meningitis, etc.

Much interest attaches to the combination of pneumonia with secondary inflammations of the lining membrane of the blood-vessels, such as arise either from spontaneous coagulation of the fibrin in high degrees of hgemitis, and its becoming dissolved into pus, or, above all, such as occur in inflammations of the spleen terminating in ulcerous splenic phthisis.

Primary pneumonia proves fatal by inducing paralysis of the lungs; also from the supervention of pulmonary oedema or of other complications, from the high degree of blood-disease and the occurrence of spontaneous coagulations in the heart and vessels, and from acute softening of the stomach and oesophagus.

Secondary Pneumonia

Secondary Pneumonia is frequently developed as a result of inflammations in other organs, when they cause the blood to assume a consecutive disease similar to the spontaneous affection which we have already noticed; it frequently also accompanies specific processes which in their nature are allied to the exudative, and hence it especially occurs in the acute exanthemata. In both these cases the pneumonia is usually lobar. Finally, secondary pneumonia may occur as a metastasis towards the termination of various forms of acute dyscrasia of the blood, which, in their course, degenerate into a croupous diathesis; amongst these Ave must place many exanthematous, and the typhous and tuberculous processes; the pneumonia in these cases is generally lobular and may even be vesicular. Under this class we may also place many of the so-called latent, symptomatic, and, as has been already remarked, the metastatic inflammations. They are combined, especially under the circumstances which we have just mentioned, with exudative (croupous) processes of various degrees of plasticity on other mucous and serous membranes.

From all that has been stated, the croupous nature of the pneumonic process in general is sufficiently clear; being always based either on a peculiar primary (spontaneous) or on a secondary disease of the blood. There can be no doubt that this condition constitutes the basis both of secondary pneumonia and of the other metastatic croupous processes so frequently combined with it, and it may also, in all essential points, be looked upon as the foundation of primary pneumonia and other primary croupous processes on the mucous membrane of the mouth, throat, and respiratory organs.

But as there are variations in the individual peculiarities, the age, and the external influences, under which croup of the mouth and pharynx, tracheal and bronchial croup, and, finally, croupous pneumonia are developed, so also may the diseased condition of the blood vary in these affections, although probably only in a slight degree; and pneumonia, if we consider it as pulmonary croup, and if we take into consideration the plasticity of the exudation, may be regarded as occupying, in adult life, the same place which in earlier life is held by pharyngeal and tracheal croup; while bronchial croup, especially in adults, forms the transition between the two latter varieties and pulmonary croup (croupous pneumonia). We now proceed to the consideration of typhous pneumonia, in consequence of the similarity of its anatomical relations to those of croupous pneumonia.