163 LECTURE LV. Pulmonary Emphysema; vesicular and interlobular. Anatomical characters of vesicular emphysema; physical signs; general symptoms; causes: treatment. Interlobular Emphysema; its anatomical characters, symptoms, cause, and cure. of the lungs. Phthisis Pulmonalis. Edema I HAVE yet one or two morbid conditions of the lungs to consider and to describe, before I go to that which is the most common and most extensively fatal of all its morbid conditions-tubercular phthisis. There is a state of the lung, or rather there are two or three different states, to which Laennec has applied the name emphysema. A very injudicious name it was for him so to impose. We are infinitely indebted to Laennec for the entirely new light which his able researches have thrown upon the morbid anatomy and the pathology of the lungs: but we have to regret that he should have employed, in several instances, a vicious nomenclature. Emphysema is a term that had long been familiar among medical men in a certain sense. It was used to express the inflation of the areolar tissue of the body with air: and surgeons still make much of it as an indication, in cases of fractured rib, that the bone has grazed the pleura, and allowed air to pass into the areolar tissue, and to diffuse itself over the chest and neck, and other parts; so that these parts, when pressed, convey a curious sense of crackling to the finger. But emphysema of the lung, as that term is employed by Laennec, includes dilatation of the air-cells of the lungs, and rupture of the partitions which separate them from each other; and also the infiltration of air into the interlobular areolar tissue, or into the subpleural areolar tissue. In strictness of language these last conditions alone should have been called emphysema of the lung. Laennec has distinguished the two species in this way. To the dilatation of the air-cells, with or without a breach of their partitions, he gives the name of vesicular emphysema: vesicular (I quote the words of Sir John Forbes' translation), or pulmonary, properly so called." Now in truth this is emphysema improperly so called. To the infiltration of the areolar tissue in or around the lung with air, i.e., to emphysema of the lung in the old sense of that word, he applies the title of interlobular emphy "the sema. We cannot change these denominations now. They hav fastened themselves upon medical language. But it is very fit that you should be aware of their inconsistency with the ancient signifi cation of the same word, and have clear notions of what in Laennec': nomenclature they are intended to express. The change called vesicular emphysema was not unknown, as a mere morbid condition, before the time of Laennec: but it had been noticed by very few writers, and practically it was wholly unattended to. Yet it is extremely common: much more so than you would suppose: and when rightly studied it is of great interest too, in relation to the general pathology of the chest. But it is still so new, and it may so readily escape observation, both in the dead and in the living body, if it be not looked for, that I shall devote a somewhat more minute attention to it, on those accounts. Laennec was undoubtedly the first to put emphysema pulmonum upon the list of definite and cognizable diseases; to point out its frequency; and to collect its symptoms. But when he affirms that, before his time, the pulmonary change which constitutes the disorder was misunderstood by nearly all those persons who had noticed it, he scarcely does them justice. "All of them (says he) seem to have thought that the derangement in question consisted in the infiltration of the cellular substance of the lungs with air." He inconsistently adds, "Ruysch and Valsalva are the only authors, as far as I know, who have observed in individual cases the dilatation of the cells ;" and with still greater inconsistency he proceeds to quote, from Morgagni, the following passage, in which this dilatation is very clearly described: "Sinistri pulmonis lobus superior, quâ claviculam spectabat, vesiculas ex quibus constat mirum in modum auctas habebat ; ut nonnullæ avellanæ magnitudinem æquarent; cæteræ multo minores erant." You will find the same change noted by Dr. Baillie, in his Morbid Anatomy: and by earlier writers than he. Vesicular emphysema, then (to adopt Laennec's phraseology), consists in dilatation of the air-cells. The enlarged cells become misshapen also in many cases. They vary in magnitude from that of a millet-seed to that of a swan-shot; nay, the cavities may even reach the size of a nutmeg or of a hen's egg: but when they are as big as this—and a fortiori when they are still bigger—the distension and vacuity are, no doubt, the result of the union of several air-cells, broken into one by the stretching or destruction of the partitions that naturally divide and isolate them. You may see the dilated vesicles very plainly through the pleura if you carefully examine the surface of the lung. They appear to the naked eye as the healthy vesicles appear when seen through a magnifying glass. Sometimes all the vesicles belonging to one lobule are enlarged, while those of the adjoining lobules are of the natural size. In that case the emphysematous lobule is conspicuous both by its peculiar colour, and by its protrusion. The surface of the lung is often rendered quite irregular and uneven by projections of this kind. Sometimes one large globular prominence is seen, like a bubble on the water, or like a little bladder springing from a footstalk: but if you examine it closely you will generally find that the footstalk is merely a constriction at the surface, and that there is as large a cavity beyond it, in the lung, as there is without. These bullæ you cannot slip about, by pressure, from one part of the pleura to another. The unevenness produced by vesicular emphysema upon the outside of the lung is manifest enough, when looked for; but the same condition of the air-cells exists also within, and there it is not so readily perceptible. The fluids which the lung contains, obscure all distinction of parts when the organ is cut. The best way of getting a fair view of the dilated cells as they appear in the substance of the lung, is to inflate the emphysematous portion, by blowing air in at the bronchial trunk which belongs to it, and then tying that trunk to prevent the escape of the air. The inflated lung should be hung up in a current of wind, so that it may quickly dry; and during the drying process it should, from time to time, be re-inflated: for else the included air gets out somehow, and the piece of lung shrinks and shrivels up. When it is quite dry, if a section of it be made with a thin sharp knife, the altered state of the air-cells, some of which are more and some less dilated, will be very conspicuous. No part of the lung is exempt from liability to these morbid changes but generally they are limited to certain portions of the organ, and they are much more common and more pronounced at its loose anterior borders, and near its summit in front, than anywhere else. Both lungs appear to be alike obnoxious to the disease; which seldom affects the one without affecting, in a greater or less degree, the other also. The parts that are emphysematous are usually paler than the rest, and sometimes they are quite white. In extreme cases the surface of the lung presents a sort of piebald appearance; large patches of it looking as if they had been bleached. This pale colour is oftenest seen towards the free edges of the lung. Sometimes those edges are rounded and thick; sometimes thinner, and folded back; while sometimes the margin is blown out, as it were, into an irregular fringe; some of the inflated portions remaining connected with the lung by slender pedicles, and thus forming appendices to it of a light yellow colour. I presume that what was thought and called a fringe of fat, garnishing the edges of the lung, in the body of King George IV., was of this kind. At least I have never seen, nor heard of, any other example of fat deposited in those organs. If you hold the emphysematous border between your eye and the light, you perceive that it is translucent: if you prick it with a pin, the puffy part surrounding the puncture sinks down; which shows that the dilated vesicles communicate together. : An emphysematous lung is not only paler, but drier also than ordinary and for the same reason. It possesses fewer capillary blood-vessels, less blood, and consequently less moisture. dry and light, and floats high upon water, like a bladder filled with air. It is If you take such a lung out of the body, having its surface embossed with irregular groups of enlarged air-cells—and if you inflate that lung, by blowing into the bronchi-the emphysematous portions will often seem to sink in, and flatten, and return to the ordinary level as the whole lung becomes distended. In point of fact, however, these portions remain permanently dilated, and the other parts near the surface, when they are sound and permeable, rise, as the air enters them, until the whole is smooth and even. Air is shut up in the emphysematous portions, which do not subgide, as the adjoining portions do, when left to the agency of their proper elasticity. Hence you will see how it is that, when the vesicular emphysema is extensive, so as to occupy nearly the whole of the lung, the lung becomes apparently too big for the case in which it is contained. Not only does it not subside when the sternum is raised, and the pressure of the atmosphere is admitted to its external surface; but it even protrudes, the moment that the opening is made. When you handle such a lung, it gives a very different sensation to the fingers from that produced by pressing a healthy lung. It feels like a down pillow. It crepitates less; the air is less easily forced out of it, and escapes slowly, with a slight hissing noise. The nature of the morbid state that I have been describing suggests at once the notion of some physical cause for it. But the mode, and the mechanical conditions, of its production, have been much misunderstood. I must confess that on previous occasions I have given you what I now know to have been an erroneous account of the generation and relations of vesicular emphysema. The permanent dilatation of the pulmonary vesicles is not attributable, as in common with others I formerly supposed, to the accumulation, imprisonment, and distending force of air shut up within the vesicles by obstructions in the air-tubes. Obstructions in the air-tubes cause an emptying of the portions of lung to which they lead-a collapse, and not a distension, of the vesicles. It is to Dr. William Gairdner that we are indebted for more correct views of these structural changes, so opposite in character; and of their mutual relation. He has shown that, in a vast majority of instances, pulmonary emphysema is a consequence of pulmonary collapse. I have always indeed been of opinion that emphysema does not occur as a primary and independent disease; that it is in every case a secondary change, the result of some pre-existing thoracic change. It is never met with alone: and according to Dr. Gairdner's testimony, pulmonary collapse is by far its most frequent concomitant. Take notice, if you please, that these two unnatural and opposite deviations from the healthy state have each its favourite place: collapse affecting chiefly the posterior portions, near the roots of the lungs, while emphysema occupies generally their fore-part, and above all, their anterior borders. It is found, too, that the tubes which belong to the emphysematous parts are rarely obstructed. Air blown into them reaches with facility the dilated vesicles. The tubes of the collapsed parts are clogged with viscid mucus. It can scarcely be doubted that collapse of certain portions of the lungs leads to emphysema of certain other portions. But it is not mere condensation and solidification of the pulmonary substance that produces emphysema elsewhere in the lung. Emphysema is not commonly found coexisting with hepatization alone, nor with solidity arising from the deposit of tubercular matter. What is there, then, peculiar to the condensation of collapse that should render it so fertile a source of subsequent emphysema? It is this-that collapse implies a diminution in the bulk of the lung, and that other modes of condensation are not necessarily attended with such diminution. For every portion of lung closed by collapse there must be a proportionate loss of bulk. But since there can be no vacuum, it follows that, as the thorax expands, more than the standard quantity of air must enter those tubes and vesicles which are not involved in the collapse. And if the quantity exceed a certain amount, dilatation of the vesicles must needs ensue. There may indeed be atrophy and reduced bulk under other forms of condensation, and if so, there may arise a correspondent |