Anatomical Changes In Emphysema

We have to do with air spaces of irregular shape and separated by partial partitions, and as the dis-tensile force acts from within, its tendency is to distend equally, and so render the spaces globular. The ultimate bronchial tubes terminate in the elongated passages called from their shape infundibula. From these passages open, by wide apertures, the air vesicles, which therefore cluster around the infundibula and are mere pouches out from them. The distensile force will act first on the infundibulum with its system of air vesicles, causing distension. The tendency will be to render the outline more globular and the cavity simpler. The partitions separating the alveoli atrophy and the infundibulum expands into a simpler cavity (a a in Fig. 355). Thus while more space is occupied there is less respiratory surface. The infundibulum continues to expand and meets with other infundibula undergoing a similar process. By mutual pressure the adjoining tissue atrophies, and the infundibula communicate by rounded apertures. The larger cavity tends to become simpler by atrophy of all partitions and septa, and so the process goes on by coalescence of neighbouring spaces and atrophy of the partitions. The enlarged air spaces thus produced are of various sizes, up to considerable vesicles or bullae.

Fig. 355. - Section of the lung in emphysema, early stage. The infundibula, a, a, a, are dilated, x 100. (Rindfleisch).

With this atrophy there is great loss of tissue and of blood-vessels. Before the actual destruction of the blood-vessels the pressure seems to cause obstruction of them so that they are not able to be injected and appear as white cords. It is stated that this obstruction is effected by the formation of white thrombi. The epithelium for the most part persists in the distended air spaces, but it is frequently in a state of fatty degeneration. Of most importance is the atrophy of the elastic tissue, because on this account the lung tissue will be prevented from collapsing as it normally does.

The lung as a whole presents alterations consistent with those in its finer structure. In general emphysema, when the chest is opened, the lungs are seen to be bulky and pale; they do not retract within the chest, and they give to the hand a soft downy feeling. They scarcely crepitate wjien handled and when pressed on the surface a pit is left. These characters are due to loss of elasticity, which renders the lung tissue less capable of retracting. The localization of the lesion is indicated by increase of bulk and change of colour, the affected parts having a light grey or pinkish colour mottled with spots and lines of pigment. Thus the Anterior margins are unduly voluminous, and the edges rounded. The enlargement is often somewhat irregular so that pieces are partially isolated by being specially enlarged. This applies more particularly to the Ear-shaped piece which projects from the anterior border of the left lung corresponding with the lower part of the heart. The Base also, on account of the insufficient support of the diaphragm, frequently shows marked evidences of emphysema, in the form of irregular rounded prominences, and the diaphragmatic surface of the lung may be convex instead of concave. This is especially the case in the left lung where the diaphragm is not supported by a solid organ as it is on the right side by the liver. Again the enlargement is very frequent at the Apices. It has been pointed out by Jenner that the right lung often presents a special bulging posteriorly at a place corresponding to the space behind the trachea.

The localization will be more various where the emphysema is complementary, and in that case will depend greatly on the locality of the cause. Thus we see it around cicatrices or contracted pieces of lung, but in nearly all cases there is a tendency to affect especially the anterior parts.

In all these places, with increase of bulk in general there is, even to the naked eye, a visible enlargement of the air spaces. Normally, the individual air vesicles are scarcely visible, but in emphysema the abnormal air spaces are plainly seen through the pleura, or on section (see Fig. 356), often giving a frothy appearance from the size of the vesicles and the delicacy of the partitions. Beyond this we may have all degrees of visible enlargement of the air spaces up to considerable bladders as large as an egg. On cutting into them there is often a creaking, crisp sound, and if the vesicles are large they collapse markedly.

The Effects Of Emphysema

The lungs are permanently increased in bulk, and the Capacity of the chest is increased. The chest is kept more or less in the condition of deep inspiration, the diaphragm depressed and flattened, the shoulders elevated, the sternum pushed forwards and outwards, and the chest more or less barrel-shaped. The heart is depressed along with the diaphragm and placed more horizontally, while it is overlaid by the edges of the lungs. The liver is pushed downwards by the flattened diaphragm.

Emphysema has a serious Effect on the circulation. We have seen that there is obstruction and destruction of the blood-vessels in the lung, with the result of producing dyspnoea from insufficient passage of blood through the lungs. By the efforts of the right ventricle, which commonly shows hypertrophy, there may, for a time, be a partial compensation. But as time goes on the compensation is liable to become incomplete, and the general results of dilatation of the right ventricle and general venous hyperemia follow. The prolonged strain will try the muscle of the heart and death commonly ensues from heart-failure, the muscular substance being not uncommonly found fatty.

Senile Emphysema

This is primarily an atrophy of the lung tissue corresponding with the general atrophy of old age. When the chest is opened the lung in this form retracts and falls backwards against the posterior wall of the chest. Hence the name applied by Jenner of "small-lung emphysema." The normal weight of the lungs is about 44 1/2 ounces in the male and 35 ounces in the female, but in senile emphysema they may be only two thirds of this weight. The air vesicles undergo changes similar in appearance to those in ordinary vesicular emphysema; their walls atrophy and the infundibula coalesce so as to form larger cavities, but this is by a simple process of atrophy. On examining the lung the increased size of the air spaces may be invisible at first, but if the lung be distended, or if after laying it open by incision it be floated in water, the large vesicles become visible. As old people are specially subject to bronchitis, senile atrophy may strongly predispose to the more ordinary form of emphysema.

Literature

Interlobular - Vikchow, Arch. f. wissensch. Heilk., iii.; Sachse, Virch. Arch., li., 1871; Guterbock, ibid., Iii., 1871; Coats, Glasg. Med. Jour., xxxv., 1891, p. 424. Vesicular - LAennec, Traite d'auscult. med., i., 348; Mendelssohn, Der Mech. der Resp. u. Circul., 1845; Gairdner, Edinb. Monthly Jour., xii. and xiii., 1851; Jenner, Med. chir. trans., ii., 1857; Eindfleisch, Path. Hist.; Thierfelder, Atlas d. path. Hist., 1872; Hertz, in Ziemssen's Handb., v. ii.; Ei'Pikoer, Prag. Vierteljahrschr. f. pract. Heilk., vol. cxxxii.; Duranu Fardel, Malad. des vieillards, 1854; Fowler, in Allbutt's System of medicine, vol. v., 1898.

Fig. 356. - Emphysema of lung, natural size. The dilated alveoli are visible.