ACUTE PNEUMONIC PFITHISIS. - To distinguish between croupous pneumonia and acute pneumonic phthisis is some times difficult. In the latter affection, however, the more gradual onset, the tendency of the fever to be remittent in type and attended with repeated chills, or chilliness; the profuse sweats; the rapid emaciation and abundant expecto ration which, as the lung breaks down, shows the presence of tubercle bacilli; the location of the lesion, which is usu ally at the apex; and the absence of herpes, all serve to differentiate the con dition from croupous pneumonia. Of course, the diagnosis of the true nature of the affection becomes apparent when there supervenes upon the stage of con solidation the evidences of pulmonary breakdown.
NEUROSES.—The frequent association of croupous pneumonia with marked nervous symptoms at times causes con fusion between this disease and menin gitis. The importance, therefore, of physical examination of the chest in all cases simulating meningitis cannot be too strongly-insisted upon, and in this ex amination the pulmonary apices must not be overlooked.
Etiology. — In its geographical dis tribution pneumonia is a wide-spread af fection. It prevails in all climates, and in this country is said to progressively increase as one passes from the arctics to the tropics. It occurs during all seasons of the year, but especially during the winter and early spring months. From the statistics of Aufrecht, Magdeberg Alstadt, of 1501 cases, 544 occurred be tween January 1st and March 31st; 462 between April 1st and June 30th. In cold weather attended with changes of temperature the predisposition is greater than during prolonged cold.
Pneumonia may occur at any age, but may be considered to be of infrequent occurrence for the first five years of life, during which period the inflammatory conditions of the lung are more apt to appear in the form of bronchopneu monia. It is of common occurrence be tween the twentieth and fortieth years of life, after which age there is a period of comparative lessened liability until the sixtieth year, when of all acute diseases pneumonia claims the largest number of deaths. An analysis of 285 cases ad mitted to the Philadelphia Hospital be tween January 1, 1897, and July 1, 1899, divided into the various decades of life, gives the following results:— Sex in itself offers neither immunity nor causes any special predisposition to croupous pneumonia. In early infancy and childhood, when the sexes are sub ject to the same environment, the liabil ity to croupous pneumonia is equal. It is only when the active period of life is attained and the two sexes live under different conditions that there is a greater prevalence of pneumonia among the male than among the female sex.
Again, when advanced age brings the two sexes once more under the influence of the same external conditions one shows but little liability over the other. Of the 285 cases at the Philadelphia Hospital 210 were males and 75 females; of course, the number of males admitted to the in stitution largely exceeds the number of females.
Occupation entails no special liability to the disease except as it may be at tended by exposure to conditions which are in themselves predisposing. Pneu monia is of more frequent occurrence among the poor and those who live under bad hygienic surroundings than among the well-to-do. Depressed influences of all kinds, both mental and physical, may be considered as of predisposing impor tance. Thus, alcoholism. both acute and chronic, is a very important factor in the etiology of croupous pneumonia, both on account of its lowering effect upon the organism in general and on account of the exposure that is apt to attend a debauch. It is these cases and those instances occurring in individuals the subjects of already existing disease which constitute, as a rule, the so-called asthenic forms of pneumonia, the sthenic types of the disease usually occurring in young and healthy robust adults. Con valescence from other acute illnesses must also be regarded as a predisposing factor. Individuals the subjects of ma larial infection are supposed to possess a peculiar liability to the disease. That some people possess an individual predis position to pneumonia must not be over looked, and one attack of the disease, so far from creating an immunity, appears to predispose the individual to subse quent attacks. The importance played by cold as a cause of pneumonia was formerly much exaggerated. At one time regarded by many as the exciting cause of the disease, it is now considered but one of a number of predisposing in fluences. That this is the true relation of exposure to cold to the etiology of croupous pneumonia is warranted by the fact that in a considerable proportion of cases no history of such exposure can be traced.
The frequency with which the affec tion follows traumatism, especially of the chest, has been commented upon. Thus Litten (Zeit. f. klin. Med., vol. xxvi, '82) in a collection of 320 cases of pneumonia found 4.4 per cent. due to injury. Of the cases at the Philadelphia Hospital already alluded to, but 2 gave a history of traumatism.
Injury alone cannot produce inflam mation of the lungs, but acts by raising the virulence of the pneurnococci already present, and by decreasing the resistance of the tissues. Piszerat (Gaz. Hebdom.
de Me'd. et de Chin, No. 6I, '98).