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

by Unknown

Increased resonance on percussion is observable over all portions of the lungs when the disease is general, but it is most marked at the upper part and along the anterior borders. When the disease is partial, the increased resonance is limited to the portions of the chest-wall over the affected areas. This sign is of course due to the greater amount of air in the distended vesicles. In very marked cases the resonance sometimes loses the vesicular and approaches the tympanitic character. There is very little, if any, further increase of the resonance on full inspiration. This is unlike what occurs in health, and is due to the fact that the capacity of the distended lungs is not relatively increased in emphysema, as it is in health, by the act of inspiration.

Over the cardiac region the normal dulness on percussion is lessened or entirely superseded by resonance from the overlapping of the heart by the distended lung. In partial emphysema the heart may escape this encroachment and its area of dulness may not be lessened; and even in some rare cases where the disease is general and far advanced the same thing may be observed, from the lung being bound by pleuritic adhesions, so that it cannot expand in the direction over the heart. But, as a very general rule, it will be found in hypertrophic emphysema that the normal præcordial dulness is lessened or absent. When this is observed the heart is in some cases forced downward, its beat being felt most distinctly in the epigastrium; and in other cases it is carried directly backward, so that its impulse can hardly be detected at all.

Over the posterior wall of the chest percussion gives a clear note at a lower level than in health, because the dilated lung extends farther down toward the bottom of the thorax.

The signs afforded by auscultation are highly characteristic of emphysema, and, like those of percussion, in direct relation with the physical condition of the lungs. The respiratory sounds are notably feebler, because the amount of air entering and leaving the lungs at each act of respiration is less than in health. The distended lungs can admit only a small amount of air at each inspiration, and from their diminished elasticity they can expel but a small amount at each expiration. This feebleness is directly proportioned to the degree of the disease, or, in other words, to the amount of distension; for the greater the distension, the less movement of the lungs and the less play of air. If the disease be unequally advanced on the two sides of the chest, the respiratory murmur will correspondingly vary, being feebler on the side where the disease is most advanced.

Besides this change in intensity, there is also an alteration in the rhythm of the respiratory acts corresponding to what has been referred to above as observable on inspecting the chest. The ratio of inspiration and expiration is always changed in well-marked emphysema—so much so as to be in many instances reversed, the expiratory occupying more than double the time of the inspiratory act. Inspiration is short and quick, because the air enters freely and the limit of the possible expansion of the lungs is speedily reached. Expiration is prolonged, because there is a loss of their normal elasticity, and an effort is made by voluntary action of the expiratory muscles to expel the stagnant residual air. This alteration in rhythm is eminently characteristic of emphysema when the disease is far advanced and occupies a considerable portion of the lungs. Feebleness of respiratory murmur is an earlier sign than alteration in rhythm, and may be observed before any marked prolongation of the expiratory act occurs and before there is any very positive increase of resonance on percussion. Hence it is of great importance if not otherwise explicable, as it sometimes is by unusual thickness of the chest-walls, because it indicates, taken by itself, an early stage of emphysema in which treatment may be most likely to be beneficial. It is sometimes found in very advanced stages of emphysema that the respiratory sounds are almost totally inaudible; but in general, while both murmurs are feeble, expiration is more appreciable than inspiration. If, however, the disease is associated with bronchitis, either constantly or intermittingly, the proper auscultatory signs of the accompanying affection may be observed, though modified by the emphysema. Thus, moist and dry râles according to the stage of the bronchitis, sibilant or sonorous, subcrepitant or mucous râles according to the size of the bronchial tube involved, may be heard, the abnormal sounds being notably prolonged during expiration.

It can hardly be doubted that the sign referred to by Laennec as "perfectly pathognomonic of emphysema," and described by him as "the dry crepitant râle with large bubbles" (râle crépitant sec à grosses bulles), is in most cases, if not always, dependent upon coexistent bronchitis. Certainly, many cases of emphysema are met with in which, in the absence of bronchitis, no such sound is heard. The signs or combination of signs which are indeed "perfectly pathognomonic of emphysema" are increased resonance upon percussion, associated with marked feebleness of respiration and prolonged expiration. This association of signs is always indicative of emphysema, because it can be explained only by the physical conditions involved in this disease.

Auscultation of the cardiac region gives results corresponding with those afforded by percussion and palpation. When the lung is distended sufficiently to overlap the heart, the sounds belonging to the latter organ will be more or less indistinct and distant, and sometimes scarcely audible. If the heart be pushed to the right or downward instead of being driven backward, the sounds may still be distinct, but they are out of place and have their greatest intensity under the sternum or at the epigastrium. The proper signs of hypertrophy or dilatation of the heart, which may be revealed on post-mortem examination, and the mechanism of which will be referred to farther on, are to a great degree masked during life; for the overlapping lung prevents the detection of increased cardiac dulness by percussion or increased impulse by auscultation.

Palpation of the chest serves to confirm the evidence supplied by inspection. The effacement of the intercostal spaces, the lessened mobility of the ribs, and the situation of the apex-beat of the heart are signs of importance of which the sense of touch takes cognizance.

COMPLICATIONS AND SEQUELÆ.—Bronchitis is one of the most frequent of the affections complicating emphysema. In the partial form of the malady it often sustains, as has been already seen, a direct causal relation to the emphysema. When the disease is diffused and general, bronchitis is sooner or later almost always encountered, and is then of a congestive rather than an inflammatory type, being often unaccompanied by fever, and in part due to interference with the circulation through the smaller bronchial arteries. For, as some branches of these vessels are distributed in the interlobular areolar tissue, and others ramify upon the walls of the smallest bronchial tubes, a constant pressure may be made upon them by the dilated air-vesicles, and this obstruction of the circulation through them may occasion passive congestion. The bronchitis accompanying advanced emphysema is generally attended with free secretion, amounting in some cases to a bronchorrhoea so profuse as seriously to imperil life by suffocation, the danger being increased by the difficulty in expectorating that exists. The discharge from the bronchi is often in such cases of a muco-purulent character. So urgent is the danger sometimes arising from this complication that unless it be relieved death may quickly ensue. The face and other portions of the surface become livid or leaden, the whole body more or less cool, the pulse weak and hurried, and copious râles are audible even without applying the ear to the chest. Life is threatened both by the accumulation in the respiratory passages obstructing the entrance of air, and by the tendency to the formation of heart-clots from the embarrassment to the pulmonary circulation and the consequent malaëration of the blood.

Another very common complication of emphysema is asthma, which, indeed, is sure to occur in greater or less degree of violence and at longer or shorter intervals in all cases where the disease has become extensive. The attacks often come on in the night, arousing the patient from sleep. The tendency to a nocturnal occurrence of asthma may be due to the recumbent position favoring passive congestion of the lungs, and to the diminished activity of the respiratory process during sleep when it is not aided by voluntary effort. From both these causes an irritation may be set up determining reflex spasm of the bronchi. Moreover, the paroxysmal occurrence of asthmatic attacks is an illustration of the general law in accordance with which morbid neurotic conditions frequently occur intermittingly, though the eccentric cause of them is constantly existing, as witnessed in the subjects of epilepsy or angina pectoris. The frequent recurrence of these attacks of spasmodic asthma is in all probability the cause of the hypertrophic state of the muscular tissue in the bronchial tubes which is often met with as a part of the morbid anatomy of emphysema.