A system of practical medicine. By American authors. Vol. 3

by Unknown

The blood-vessels in the cell-walls are diminished in calibre by the atrophy of these walls and by the constantly-increasing air-pressure, so as to admit only the watery part of the blood; and thus is explained the pigmentary change in the surrounding tissues where the blood-corpuscles collect. Ultimately, many of the vessels are obliterated, and the backward pressure thus induced extends to the pulmonary artery, and thus gives rise to hypertrophy and dilatation of the right side of the heart, as already explained. It is this pressure on the vessels in the alveolar walls that causes also passive hyperæmia of the bronchial mucous membrane, and thus produces a tendency to bronchitis, which so often occurs as a consequence of emphysema, while, again, primary bronchitis is frequently a factor in the production of the disease. The principal change in the bronchial tubes, in addition to the hyperæmia and softening of their mucous membrane due to coexisting bronchitis, is a hypertrophic thickening of their muscular coat, the result probably of repeated spasmodic action in the asthmatic attacks.

DIAGNOSIS.—The chief points by which the diagnosis of emphysema is determined have already been referred to under the head of Symptoms and Signs. The most important of these are the auscultatory signs; for, although the general symptoms and history of the case may point with probability to the nature of the malady, yet if these alone be regarded other affections may easily be confounded with it.

The auscultatory signs proper to emphysema are increased resonance upon percussion, feeble respiratory murmur, and prolonged expiration. Any one of these physical signs may be met with in other affections than emphysema, but when they occur conjointly they point only to this disease. In addition to them the alteration in the form of the chest-wall, so that it becomes rotund or barrel-shaped, and the asthmatic character of the breathing, are important indications. The diseases most likely to be mistaken for emphysema are phthisis, bronchitis, pneumothorax, and pleural effusion.

In the early stage of phthisis feebleness of respiratory murmur with prolonged expiration might suggest the existence of emphysema; but, apart from the fact that these signs at any time when a doubt might be felt are generally confined to the top of the lung in phthisis, the diminished percussion resonance, the bronchial or broncho-vesicular breathing, the bronchophony or bronchial whisper, and increased vocal resonance and fremitus—all of them proper signs of phthisis and all wanting in emphysema—would by their presence or absence clearly establish the differential diagnosis between the two affections. In more advanced phthisis, when softening has taken place and a cavity exists, difficulty in discriminating between the two diseases could hardly arise.

Emphysema is so frequently associated with chronic bronchitis and with intercurrent attacks of acute bronchitis that it is often important to determine whether these latter affections exist independently or are complications of the emphysema. The question is in general settled by the history of the case and by the conformation of the chest, showing whether previous dilatation of the air-cells has taken place or not; as also by the presence or absence of the special signs of emphysema when those of the bronchial affection are encountered.

Capillary bronchitis, from the urgent dyspnoea attending it and the vesiculo-tympanitic resonance which it sometimes presents, especially in the upper and anterior parts of the chest, may possibly be mistaken for emphysema, from which, however, it may be distinguished by the quickened pulse and high temperature that belong to this form of bronchitis, as also by the rapid diffusion of the subcrepitant râle over both sides of the chest in capillary bronchitis; whereas this sign is absent or less marked in emphysema. Moreover, capillary bronchitis is most common in childhood, when diffused emphysema is less frequently met with.

Pneumothorax is characterized by distension of the chest and increased percussion resonance—signs which belong also to emphysema; but the possibility of error is avoided by the consideration that whereas in emphysema the respiratory sound is feebler than natural, in pneumothorax it is strongly exaggerated and amphoric in character; and there are also the additional signs of metallic tinkling and the plashing noise or "Hippocratic succussion sound" made by moving the body backward and forward. Moreover, even as regards the sign in which the affections would appear to resemble each other, a difference may be observed on careful examination; for the percussion note of pneumothorax is purely tympanitic, while in emphysema the increased resonance has still a vesicular character to some degree. Pneumothorax, again, is always a unilateral affection, and emphysema is almost as constant in its occurrence on both sides of the chest.

It might appear that there would be little liability to confuse emphysema with pleural effusion, in view of the very general presence of dulness on percussion in the latter affection and of resonance in the former. But in some cases of fluid effusion in the chest a degree of tympanitic resonance is met with, more especially in children. J. Lewis Smith remarks that "as a rule in the pleuritis of children, at a certain stage of the effusion, percussion produces a sound which is either decidedly tympanitic or which partakes of the tympanitic character."¹¹ In both affections, moreover, there may be enlargement of the chest. The doubt, if it arise, may be settled by the consideration that in emphysema the altered resonance and the enlargement are on both sides; whereas in pleurisy these signs are in general on one side only; and, further, the enlargement is more marked at the top of the chest in emphysema and at its base in pleural effusion.

¹¹ Diseases of Children, 5th ed., p. 607.

In concluding the account of the diagnosis it may be said that when the history of a case, the frequent or constant occurrence of dyspnoea, and the more or less rounded conformation of the chest make the existence of emphysema probable, this probability may be converted into a certainty by the discovery of resonance on percussion, feeble respiratory murmur, and prolonged expiration.