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

by Unknown

While, therefore, it is probable that in some cases and to a certain degree inspiration may have a share in occasioning emphysema, yet expiration is to be regarded as a more important and more frequent factor in its production. This, at least, is probably the case in partial and lobular emphysema, and in some instances of the lobar form where the disease gradually spreads throughout a lobe. But in rapidly-diffused and extensive lobar emphysema such an explanation cannot always be admitted, because sometimes the disease advances steadily, so as to involve the greater part of one or both lungs without the occurrence of any paroxysms of cough which could distend the air-cells by their violent expiratory efforts. In such cases the only distending force would seem to be that of ordinary inspiration, which, while it might have no effect upon healthy lung-tissue, may easily be supposed to exercise sufficient dilating power upon air-cells, the walls of which are in a state of degeneration, and, thus being unnaturally weak, yield to pressure.

SYMPTOMS AND SIGNS.—One of the earliest symptoms of emphysema is shortness of breath; and, though at first it may not be very marked, yet as the disease advances it becomes more and more urgent, especially on going up stairs or walking up hill. Distension of the stomach by a full meal is likely to induce it, and even a slight degree of bronchial catarrh may render it extremely distressing. This symptom is due chiefly to two causes: First, the obliteration of numerous capillaries in the pulmonary system, occasioned by the thinning and destruction of the cell-wells in which they ramify, interferes with oxygenation, so that an increased number of inspiratory acts is required to supply the deficiency, and thus respiration is hurried; and, secondly, the impairment of the natural elasticity of the air-vesicles prevents the expulsion of their contents; the residual air remains, therefore, unchanged, and cannot supply oxygen to the blood; and thus increased expiratory efforts are made in order to expel the stagnant air and obtain a fresh supply. Notwithstanding this increase of both inspiratory and expiratory action, the movements of the chest are but slight. As far as bronchial catarrh is a cause of dyspnoea in emphysematous patients, improvement may take place in the warm dry weather of summer, when this symptom is often much mitigated.

Cough is a very constant symptom, varying in degree with the extent of bronchial catarrh. The act of coughing is feeble and expectoration is effected with difficulty—so much so that sometimes the retained secretion threatens suffocation.

Asthma occurs in paroxysms, and as a distinct phenomenon from the dyspnoea which is more or less constant. The asthmatic seizures often come on in the night after the patient has been asleep; they are characterized by orthopnoea and constriction in the chest, and generally subside with free expectoration.

The physical signs of emphysema are highly characteristic and of great importance. On inspection a peculiar conformation of the chest is observed when the emphysema has lasted for some time, the departure from the normal form gradually increasing in the progress of the disease until, in advanced cases, a degree of deformity is produced which is strikingly characteristic. In the earlier stages, or if the emphysema is local and partial, the alteration in the chest-wall consists only of a prominence corresponding with the dilated portion of the lung. But when the disease is general and occupies a considerable portion of both lungs, a rounded, convex, or barrel-like form of the thorax is produced, most noticeable in the upper part, and due to increased prominence of the ribs. The thoracic portion of the spine becomes more curved, and thus throws the shoulders forward, producing a stooping attitude. The intercostal spaces at the upper part of the chest are frequently effaced by the pressure of the enlarged lung, while at the lower part the depression of these spaces may be increased, especially during inspiration, by the action of the diaphragm. The enlargement of the thorax as a whole is chiefly due to the changes in its upper part, the lower part appearing sometimes by contrast to have lessened in volume. This, however, is in most cases apparent rather than real; but in some instances the dimensions in the lower part of the chest are actually lessened.

The respiratory movements in well-marked emphysema are characteristic and peculiar. The dilatation of the chest which is sought to be accomplished by muscular action is small and disproportioned to the amount of effort put forth, notwithstanding that the need for air keeps the sterno-mastoid and scaleni muscles in constant action. The reason of this is that, the lungs being distended nearly to their utmost capacity, there is but little room for further expansion. As there is only slight enlargement on inspiration, so with expiration the walls of the thorax contract but little at their upper part.

The result, therefore, of their muscular efforts is that the ribs are lifted and the sternum carried forward, so that the whole chest rises and falls in respiration as if its walls formed a solid case. But the character of respiration is by no means the same in all cases of emphysema. More than forty years ago Stokes⁴ called attention to the different modes of breathing in different cases accordingly as there is or is not displacement of the diaphragm; and his observations have more recently been reaffirmed by Waters⁵ and others. In the one class of cases the diaphragm retains its normal position and the upper part of the chest is very prominent, probably because the disease is chiefly in the upper portion of the lungs. Here there is but little descending movement of the diaphragm in inspiration and the abdomen remains flat. In the other class the diaphragm has been displaced and pushed downward by the enlarged lungs, which have probably been involved in the disease throughout their whole extent. In these cases the abdomen is protruded more or less with every inspiration. The difference between the two types of breathing is important, as in the latter class of cases there is more advanced and extensive disease than in the former, the symptoms being more urgent, and especially the dyspnoea greater. Inspection of the chest shows that the movement of inspiration is more quickly accomplished than that of expiration, which is prolonged, labored, and often wheezing in character.

⁴ Diseases of Chest, 2d ed., p. 173.

⁵ Diseases of Chest, p. 140.

Percussion and auscultation furnish signs of the utmost importance for determining the existence of emphysema which are in direct accordance with the physical conditions giving rise to them.