The malarial conditions which give rise to this type of pneumonia occur more frequently in our Southern and Western States than in any other part of the world.
PHYSICAL SIGNS.—By studying the physical signs of croupous pneumonia in connection with the different stages of its morbid anatomy, their importance as elements in diagnosis and prognosis can best be appreciated.
Stage of Engorgement.—The physical signs indicative of the first stage of croupous pneumonia are usually present within twenty-four hours after its invasion. If the pneumonia is central, their appearance may be delayed until the third day.
Inspection.—On inspection the movements of the affected side are noticed to be more or less restricted, while the unaffected side moves as in health. In double pneumonia the respiratory movements will assume a costal type, attended by an increase in the abdominal breathing.
Palpation.—On palpation there is more or less increase in the vocal fremitus on the affected side. The degree of increase corresponds to the extent of the engorgement. It must always be remembered that normally the vocal fremitus is more marked on the right side than on the left.
Percussion.—There is slight dulness over that portion of the chest-wall which corresponds to the affected portion of lung: its extent varies with the amount of lung involved. It is never well marked until the end of the first stage, although the pulmonary capillaries are engorged with blood from the commencement. Even at the end of this stage the intensity of the percussion sound, although diminished and muffled, has a slightly tympanitic quality, due to the fact that the exudation has not completely displaced the air in the distended alveoli. Very extensive central pneumonia may fail to give either increase in vocal fremitus or dulness on percussion until the second stage is well advanced. Absolute dulness during this stage is of rare occurrence.
Auscultation.—During the dry stage, which according to some41 is said to precede the exudation stage, there will be noticed a feebleness and unnatural dryness of the respiratory murmur. Sometimes it is harsh, at others feeble and loses the peculiar breezy, rustling quality of the normal respiratory sound. If it is less intense over the affected portion of the lung, it is exaggerated over the unaffected portion. These changes are apt to pass unrecognized unless auscultation is practised frequently and early in the disease. As soon as the engorgement is well marked and exudation takes place into the air-cells, fine crackling sounds are heard at the end of inspiration. These sounds are called crepitant râles, and are regarded as the characteristic sign of the first stage of pneumonia. They resemble those produced by throwing salt on live coals or rubbing the hair in the neighborhood of the ear between the fingers. These râles do not necessarily depend upon the presence of fluid in the alveoli, but may arise from the sudden separation of the alveolar walls at the end of inspiration when they have been agglutinated by a tenacious exudation. They are as numerous as they are minute, are unaffected by coughing, and remain audible over a circumscribed space from twelve to twenty-four hours. Whenever the pneumonic stages follow each other in rapid succession, the crepitant râle may not be heard. It is rarely present in a pneumonia which is developed during an attack of acute articular rheumatism. With the crepitant râle the respiratory murmur is feeble or assumes a broncho-vesicular character.
41 Stokes.
When, as often happens, pneumonia has been preceded by or complicates any other thoracic affection, the crepitant râle will be mingled with the sounds arising from that particular condition. It is said42 that bronchial breathing is sometimes heard in this stage of pneumonia. The voice-sounds undergo slight increase in their intensity over the seat of the pneumonic engorgement.
42 Traube, Annal. der Charité, i. 286.