EMPHYSEMA.
BY SAMUEL C. CHEW, M.D.
DEFINITION.—The term emphysema is derived from [Greek: emphysaô], to inflate, and signifies an increased amount of air in a part or the whole of one or both lungs. Accordingly as the situation of this excess of air is (a) in the air-vesicles or (b) in the connective tissue between the lobules, emphysema is divided into Vesicular emphysema and Interlobular or extra-vesicular emphysema.
HISTORY.—These two affections are different pathologically and anatomically, vesicular emphysema being a much more common and important affection than the interlobular form. The distinction between the two forms was first drawn by Laennec. Previously to his time the essential difference between them was unknown; and, as the accurate diagnosis of the disease can be made only by auscultation, its existence was no doubt very often entirely overlooked. It has been remarked by Rokitansky1 that "had Laennec done nothing else for medical science, his discovery of this diseased condition, and of the causes giving rise to it, would have sufficed to render his name immortal."
1 Path. Anat., vol. iv. p. 53, Am. ed.
VESICULAR EMPHYSEMA.
Vesicular emphysema may be defined as an absolute or relative increase in the amount of air contained in the vesicles of a part or the whole of one or both lungs. As a substantive disease it occurs in two principal forms—hypertrophic and atrophic; but besides these it is met with as a secondary affection due to other diseases and limited to certain areas of the lungs, sometimes acute and sometimes chronic in its production and duration. It will therefore be best to consider the disease under the following different forms:
1st. Acute lobular emphysema;
2d. Chronic lobular emphysema;
3d. Hypertrophic lobar emphysema;
4th. Atrophic lobar emphysema.
1. Acute Lobular Emphysema.
This form of the disease is the result of the rapid distension beyond their natural size of air-vesicles which had previously been healthy. It is most frequently met with in children and as the consequence of bronchitis or whooping cough. The paroxysms of cough occurring in these affections, especially in the latter, are attended by deep inspirations, by which the vesicles are directly distended, and by violent expiratory efforts, with closure of the glottis, so that the air is forced into those portions of the lungs where there is least resistance, particularly at the apex and along the margins. In a large proportion of cases of acute lobular emphysema, when the distending cause is removed by the cessation of the cough, the vesicles return to their normal size through their natural elasticity, which has not been destroyed. But in some cases, when the cough has been of unusual violence or of very long duration, the change may be permanent through loss of this elasticity, and thus a form of chronic lobular emphysema is produced.
SYMPTOMS AND SIGNS.—Unless emphysema of this form is extensive and extreme in degree, it is not attended with symptoms additional to those of the affections giving rise to it. When very great it may occasion increased percussion resonance.
TREATMENT.—The treatment is only what is required by the causal affections.
2. Chronic Lobular Emphysema.
In many cases emphysema is confined to a limited number of lobules, especially at the apices, the anterior borders, or about the base of the lung; and being gradual in development and permanent in duration, it is then termed chronic lobular emphysema. This is the form frequently met with in the different varieties of pulmonary phthisis, in which its development seems supplementary to the incapacitation of other portions of the lung. The lobules nearest to the surface of the lung or immediately beneath the pleura are found to be most distended, so that they often project beyond the adjacent surface.
Chronic lobular emphysema is chiefly of interest in connection with the other pulmonary diseases which give rise to it. The mechanism of its production is like that of acute lobular emphysema, but the diseases occasioning it being chronic the emphysema to which they give rise is equally permanent. At the apex of the lung, its most common situation, it is very often associated with tubercle in a calcareous state. The changes accompanying this deposit of tubercle favor the loss of elasticity in the vesicles of the apex, and the violent expiratory efforts, with closure of the glottis, occurring in the attacks of cough to which phthisical patients are subject, force the air into this part especially, and also into other regions of less resistance, and thus occasion permanent distension of the vesicles.
SYMPTOMS AND SIGNS.—The signs of this form of emphysema are so often masked by those proper to phthisis that the detection of the former is difficult or impossible. This, however, is of no practical importance in respect to treatment. At times the distension of the vesicles at the apex is so great as to produce bulging in the supra-clavicular region and to overcome the dulness due to deposit by the resonance it occasions.
TREATMENT.—No special treatment beyond that of the causative affections is required.
3. Hypertrophic Lobar Emphysema.
This is a substantive affection, and is much the most important form of the disease, both in its origin and development and in the consequences to which it leads. Though sometimes limited to one lung, or even to a single lobe of one lung, yet it more commonly involves the greater part of both lungs, which are increased in size, as shown by the alteration of the contour of the chest during life and by the appearance of the organs after death. This enlargement of a lobe or of a whole lung is of course the aggregate of the increase in size of the individual vesicles, the changes in which form the pathological units of the disease.
ETIOLOGY.—In no disease is the study of etiology as throwing light on treatment, both medicinal and hygienic, of more value than in emphysema, the important question being as to whether it takes its origin from some immediate mechanical cause acting upon the healthy cell-walls, and thus distending them, or whether they suffer such distension only when they have been previously weakened by some degenerative process in their tissue. The importance of determining this point correctly with reference to treatment is obvious.
In partial and lobular emphysema the change may have been wrought by causes mechanical in their nature and directed specially to the affected parts, such as have been already referred to; but in the general diffused or lobar form of the disease, in which by degrees the greater part or the whole of a lung is involved, we are almost compelled to assume the existence of some degenerative process or tendency coextensive with the malady and determining its existence. That any one form of degeneration is present in all cases has never been proved; indeed, it may be said to have been disproved. Rainey's view, that the change in the air-cells is essentially dependent on fatty degeneration of their walls, was based mainly on observations made upon a single case, and, although favored by the eminent authority of C. J. B. Williams, it has not been substantiated. The same thing must be said of Sir William Jenner's teaching, that fibroid degeneration is the essential lesion. Though both fibroid and fatty changes are found in not a few cases, yet in others a careful examination has failed to detect either the one or the other of them, so that neither can be regarded as the essential condition explaining all cases. Nevertheless, it is probable in the highest degree that a degenerative change of some kind, due to imperfect or perverted nutrition of the cell-walls, always exists in general lobar emphysema, though its nature may sometimes elude observation.
In cases of well-marked emphysema there may be no discoverable morphological changes in the walls of the alveoli, though, as remarked by Hertz,2 "a tissue-relaxation may be present in the lung without our being able to recognize any corresponding microscopic abnormality."
2 Ziemssen's Cyclop., vol. v. p. 373.
It may be said, then, that while in partial or local emphysema the alteration in the air-vesicles may be effected by extraordinary efforts brought to bear upon healthy cell-walls, in general or lobar emphysema, on the other hand, it may be produced by ordinary efforts acting upon weakened and diseased cell-walls. The morbid change is probably not in all cases alike, being sometimes fatty, sometimes fibroid, degeneration, and in other cases of a kind not ascertained.
In addition to other considerations, the markedly hereditary nature of emphysema in not a few instances would of itself render the existence of some constitutional predisposing cause highly probable. On this point A. T. H. Waters3 quotes the observations of Greenhow and Jackson. Out of 42 cases collected by Greenhow, 23 showed an hereditary tendency, and in 28 reported by Jackson, 18 were of emphysematous parentage. In stating his belief that substantive or general emphysema is the result of some degenerative process, Waters bases it on the following considerations: 1st. The high degree of development which the disease often reaches, without any previous history of violent or long-standing cough, in connection with either bronchitis, whooping cough, or any similar affection. 2d. The frequency with which the disease attacks the whole of both lungs, and the uniform character of the morbid changes often observed throughout all parts of the lungs. 3d. The hereditary nature of the disease, as shown by observations. 4th. The manner in which the disease is influenced by certain remedial measures which are known to act beneficially on other diseases attended with degeneration of tissue.
3 Diseases of the Chest, pp. 122, 123.
As to the nature of the immediate exciting cause of emphysema, whether in the general or local form, different views have been maintained. The most important of these are the inspiratory and expiratory theories.
The former of these theories, that in accordance with which the disease is referred to inspiratory action, was maintained by Laennec, and under the influence of his authority was at one time generally accepted. In accordance with this view, the existence of bronchitis is an important factor in the production of emphysema, as undoubtedly it often is in the lobular form. The dilatation of the air-vesicles was attributed to their over-distension by inspiratory efforts allowing the free entrance of air, the escape of which was impeded by bronchial mucus. Inspiration was thus regarded as a more powerful act than expiration, which was considered too feeble to drive the air beyond the accumulated mucus. In this way the air was supposed to accumulate in gradually increasing amount within the cells, which thus became distended.
But in opposition to this view it has been shown by Hutchinson's researches that Laennec was wrong in supposing inspiratory power to be greater than that of expiration; and it is further opposed by the researches of Mendelssohn and Traube, and those of Gairdner, which have shown conclusively that the presence of a pledget of mucus in a bronchial tube, so far from causing distension of the air-vesicles to which it leads, must ultimately ensure their collapse. The collapse thus occasioned, which is most common in the lower parts of the lungs, may lead, partly perhaps through inspiratory pressure, to vicarious emphysema in the upper portions, which receive a relatively larger quantity of air, in accordance with Williams' theory of negative inspiratory pressure.
It is true, then, as maintained by Laennec, that bronchitis may occasion emphysema, but the emphysema does not occur in the vesicles to which the affected tubes directly lead, nor from the force of inspiration applied to these vesicles, as Laennec taught, but in other portions of the lungs.
The expiratory theory affords a more satisfactory explanation of emphysema than does the inspiratory theory, and one more completely in accordance with the physiology of respiration and the anatomy of the thorax.
In ordinary expiration, in which the lungs are uniformly and equably compressed by the chest-walls, there is nothing tending to force air into one part of these organs more than into another, and thus produce emphysematous dilatation. But in forced expiration, such as occurs in the act of coughing, it may be plainly seen, if the chest be uncovered, that the air is driven upward to the top of the lungs, so as to produce a perceptible bulging in the supra-clavicular region. This bulging is notably increased in the coughing-spells of emphysematous subjects; and this fact is urged by Sir William Jenner both as throwing light upon the expiratory act as a principal factor in the disease, and as accounting for the special frequency of emphysema in the upper parts of the lungs. The explanation of this phenomenon is found in the circumstance that in the strong expiratory efforts of coughing the abdominal muscles force the diaphragm upward, and thus compress the lungs from below; at the same time the strong lateral anterior and posterior thoracic walls resist pressure, while the superior part of the thorax, covered over with fascia, but not completely protected by a bony structure, offers least resistance. To this unprotected part of the lungs and to the free margins and borders, which contain normally the smallest amount of air, will the strong currents produced by violent expiratory efforts be driven, so as to cause distension of their vesicles. Thus, the frequent coughing-spells of bronchial catarrh, so commonly associated with emphysema, give rise to the expiratory efforts which are the immediate cause of the emphysema.
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.
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.
The structural alterations of the heart that occur in emphysema are the results, more or less directly, of the mechanical conditions involved in the disease. Earliest in the sequence of changes affecting this organ are non-compensative hypertrophy and dilatation of its right chambers; and by some writers it has been maintained that the alterations due to emphysema are found only on this side of the organ. This, however, has been completely disproved by extended observations, and it has been shown that left hypertrophy and dilatation, while not such direct consequences of emphysema as the corresponding changes on the right side, are yet frequently encountered, and are plainly due to the disease in the lungs.
The hypertrophy and dilatation of the right chambers of the heart are easily understood when it is considered that the constant pressure of the enlarged air-vesicles of the emphysematous lungs interferes more and more with the circulation through the pulmonary capillaries, and that there is thus a constant impediment to the onward course of the blood from the pulmonary artery, and a continuous backward pressure within the right ventricle and auricle. The effort to overcome this pressure leads to hypertrophy, and ultimately, as this effort is less and less effective, to dilatation of the right chambers.
It would appear as though the readiness with which the alterations on the right side of the heart may be explained has led, if not to their being more frequently observed, yet at any rate to their being more emphasized, than are the corresponding changes on the left side. Some writers have referred only to those on the right side, giving the correct explanation of them, but making no mention of the similar condition on the other side. Thus, Rokitansky6 refers to the obstruction to the circulation occasioned by the expansion of the air-cells in pulmonary emphysema as one of the causes of dilatation of the right ventricle and auricle, but says nothing of similar changes on the left side. Other pathologists, however, as Lebert and Gairdner, have shown that at least in long-standing emphysema the left side is also not infrequently involved in disease.
6 Path. Anat., vol. iv. p. 130.
What explanation, then, is to be given of those changes in the left chambers which, if less frequent than hypertrophy and dilatation on the right side, are yet certainly not uncommon? Evidently, they cannot be referred to obstruction in the pulmonary circulation; for this, while producing backward pressure into the right compartments, must, on the contrary, lessen the amount of blood received by the left chambers, which therefore have no excessive labor thrown upon them from this cause, and so cannot become hypertrophied in such a manner.
The explanation is probably to be found partly, as suggested by Waters,7 in the altered position of the heart occasioned by the emphysema, and partly in the remora of the venous circulation.
7 Diseases of the Chest, p. 152.
There are thus two factors to be considered, the first of which applies to the right heart as well as to the left. As to this first, the more extensive the emphysema the greater is the degree of displacement that the heart undergoes; and as the normal position of the ventricles with reference to the arteries emanating from them offers the easiest course to the blood-currents, any departure from this position causes an embarrassment, and consequently increased labor, in the left chambers as well as the right; hence one explanation of the hypertrophy on both sides. As to the second factor, the obstruction to the general capillary circulation necessitates an increased effort of the left ventricle to overcome it; and so, as far as it is concerned, another cause of hypertrophy is in operation.
It is frequently observed in advanced emphysema that there is a marked disproportion between the forcible heart-beat and the feeble radial pulse, the former being due to the hypertrophy, and the latter to the small amount of blood received and propelled by the heart.
Besides these changes in the size of the heart and the thickness of its walls, constituting hypertrophy or dilatation as the case may be, a displacement of the entire organ is a not uncommon consequence of emphysema. The direction of this displacement may vary, so that it may be either directly backward, the heart being overlapped by the distended lung, or it may be downward or to the right of the sternum. A much greater degree of displacement of the heart may result from the pressure of pleural effusion than from emphysema of the lung; but when due to pleurisy it is generally of shorter duration and admits of perfect restoration, whereas when caused by emphysema it is usually permanent. The writer has at present under his care a case of extreme displacement of the heart to the right, the apex-beat being felt and seen to the right of the sternum; but in this patient, while extensive supplementary emphysema of the left lung, due to the almost complete incapacitation of the right lung, has probably had a share in causing the displacement, yet a more important cause of it has been contraction of the right side of the chest, the result of absorption of an old pleural effusion which has left the lung bound back and adherent. This case closely resembles one reported by Stokes as presenting "the singular phenomenon of the displacement of the heart to the right side, consequent on the removal of an effusion of the right side."8
8 Diseases of the Chest, p. 467.
Dropsy is to be regarded as one of the most notable complications and consequences of emphysema; for when the disease is of long standing the loss of balance between the arterial and venous circulation occasioned by the obstruction to the passage of blood through the lungs gives rise ultimately to effusion of the serum, which is first seen in the lower extremities, and may subsequently become general.
In consequence of the disturbances in the circulation and respiration which have been considered, it is not surprising that the nutritive function should be impaired, as is found often to be the case in the subjects of old emphysema, who present a cachectic and anæmic appearance, partly due to malaëration of the blood, and partly to imperfect performance of the assimilative functions occasioned by passive congestion of the alimentary tract. Still another cause may be found, as suggested by Hertz,9 in the insufficient supply of the elements received from the lymph through the imperfect emptying of the thoracic duct into the distended left subclavian vein.
9 Ziemssen's Cyclop., vol. v. p. 382.
There has been much discussion as to the connection between emphysema and pulmonary phthisis, some pathologists having held that the two affections are incompatible with each other, and that emphysema may thus exercise a prophylactic influence against phthisis. Careful and extensive observations furnish no valid grounds for such a belief. So far as supplementary emphysema is concerned, it is a common thing to find emphysematous patches at the bases and along the margins of lungs the apices of which are tuberculous. In such cases the increased inspiratory labor thrown upon some portions of the lungs in consequence of impaired function of other parts accounts for the emphysema. But, besides this common condition, cases are met with in which the emphysematous portions are themselves beset with tubercle. Such a case is reported by Waters,10 in which an emphysematous lung was found studded with tuberculous matter, which on microscopic examination was seen in the air-sacs and ultimate bronchial tubes.
10 Diseases of the Chest, p. 156.
While emphysema ensures no absolute immunity from tuberculous diseases of the lungs, yet the physical condition involved in it does lessen the liability to tuberculous deposit, which is favored by active hyperæmia, and active hyperæmia is not apt to occur in an emphysematous part of a lung. It likewise lessens the liability to such pulmonary affections as hæmoptysis, oedema, and perhaps pneumonia. The diminished pulmonary circulation occasioned by the shrinking and obliteration of the capillaries explains the infrequency of hæmoptysis. The same cause, together with the smaller amount of interlobular areolar tissue that the emphysematous lung contains, lessens the liability to oedema, because there are both less blood from which the serum can be effused and less of the tissue in which it can be collected and held. And the infrequency of pneumonia in an emphysematous lung is owing to the absence of conditions favoring hyperæmic changes.
DURATION AND TERMINATIONS.—No definite limit can be assigned to the duration of emphysema, as the progress of the disease varies very much in different persons according to the underlying cause, and according also to the care taken in avoiding those influences which promote its development, such as physical exertion or exposure to cold and damp. Many persons with extensive emphysema, if they can secure favorable climatic conditions, and thus escape attacks of bronchial catarrh, will live on for years in comparative comfort, whereas in others the disease may advance with rapidity to a fatal issue if their situation in life necessitates hard work or exposure to causes that induce frequent attacks of bronchitis. The immediate cause of a fatal termination is generally either apnoea resulting from extensive bronchitis, or asthenia from impaired action of the heart, or both of these conditions together.
PATHOLOGY AND MORBID ANATOMY.—From examinations made at various stages of the disease in those who have died of emphysema it is seen that the earliest change is a dilatation of the air-sacs, which become gradually more distended, their walls growing thinner, until they may yield at some points and perforations occur. As the disease advances the perforations become larger and more numerous, until the walls are so far destroyed that several sacs or even lobules are blended together, forming only one cavity. The alveoli may be dilated to the size of a mustard-seed, or even a pea, without undergoing rupture, and may thus become visible by the unaided eye; but when the emphysematous spaces are as large as a hazelnut or small walnut they consist of numerous air-sacs, or even of several lobules, fused together by the atrophy and breaking down of the interalveolar and interlobular tissues. When the cavities thus produced by the fusion of several sacs or lobules are in the subpleural portion of the lung, they will sometimes project beyond the adjacent surface, so as to form appendages of the size of a small walnut which appear to be connected with the lung by a pedicle. It is remarked by Waters that perforation of the cell-walls is much more common in lobar than in lobular emphysema, even though the dilatation of the sacs may be as great or greater in the latter than in the former affection; which is due, no doubt, to the fact that the extensive and diffused changes in the lobar form are dependent upon a degenerative process, in consequence of which the walls are specially prone to give way.
All the changes just referred to, from the earliest and slightest degree of distension to extreme attenuation and perforation of the walls, with final coalescence of several sacs and the formation of appendages, may be met with at the same time in different parts of the same lung. The most advanced changes are found most commonly at the apices and free margins of the lungs, while in the deeper parts an earlier stage only may have been reached.
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.
PROGNOSIS.—The circumstances, apart from treatment, which especially affect the prognosis of emphysema are the form in which the disease occurs and the ability of the patient to secure immunity from influences which may increase the malady itself or the attendant bronchitis, such as hard work, great exertion of the respiratory organs, and exposure to cold and damp.
Acute supplementary emphysema, even when it affects considerable portions of both lungs, may entirely disappear and the vesicles be restored to their integrity on the removal of the underlying cause. Thus, the vicarious dilatation of air-cells following acute bronchitis or whooping cough in children may leave no sign of its previous existence after recovery from these diseases. In general, the shorter the duration of the causal diseases, the more likely is the emphysema to disappear; for if it be maintained for a considerable time, the elasticity of the cells may be so damaged that they may never return to their natural size.
In hypertrophic lobar emphysema the prognosis in most cases is unfavorable as regards perfect recovery; while yet the disease may not materially shorten life, and with proper care may be compatible with a fair degree of comfortable existence. And, indeed, even in this form of the disease, provided it do not affect a great extent of lung and have not been of very long duration, there is in some cases ground for hope of ultimate recovery, with restoration of the air-cells to their normal condition. Modern methods of treatment have rendered the prognosis in such cases somewhat less unfavorable than it was once held to be.
TREATMENT.—The treatment of emphysema comprises several distinct objects: 1st, the arrest of the degenerative changes which may be going on in the walls of the air-vesicles, and which favor their dilatation; 2d, the restoration, as far as is possible, of the integrity of the lungs, so that they may resume their natural size; 3d, the relief of bronchitis, asthma, and dropsy, which are associated as secondary affections with the primary disease.
To meet the first of these indications, the arrest of degenerative change, iron is among medicinal agents the one most to be relied upon; for, though neither it nor any other means has power to restore loss of tissue or to reproduce integrity of structure when several alveoli are fused into one cavity by the breaking down of their partition-walls, yet by enriching the blood it may improve the nutrition of these cell-walls so that the tendency to dilatation and rupture may be checked. Iron steadily administered in small doses is the best means for effecting this end, and if the patient object to one form of the metal after using it for some time, it may be changed for another. The best preparation of the drug is probably the tincture of the chloride, and one of the best forms for administering this medicine is the mixture of acetate of iron and ammonium (Basham's mixture) introduced into the U. S. Pharmacopoeia of 1880. This is especially valuable, when any dropsical effusion exists, on account of its gentle diuretic action. In addition to iron, other agents promotive of nutrition, such as cod-liver oil and the hypophosphites, may be used with the same view. Stomachic tonics, such as the simple bitters and pepsin, may be useful by aiding digestion and nutrition; and at the same time, by preventing the formation of flatus, they may relieve the dyspnoea caused by upward pressure on the diaphragm. That real benefit may be derived from such measures is beyond doubt; and it is to be feared that some practitioners, in their conviction that no cure can be wrought in those parts of the lung which have actually undergone wasting and rupture, have to too great an extent neglected the use of means which may at least prevent the advance of similar changes in other parts, and thus tend to stay the progress of the disease.
Deep and hurried respiration will increase the air-pressure within the yielding vesicles; for this reason active exercise is objectionable, especially walking up hill, and the use of wind instruments is to be strictly prohibited. Indeed, as regards this last cause of respiratory pressure the patient's inability to practise is in general warning enough, but in the early stages of the affection a caution against it may be necessary.
The suggestion of the use of strychnia against emphysema is not founded on a correct knowledge of the mode of action of this drug; for, although it may stimulate muscular contractility, it has no influence upon the elasticity of the air-cells and no power to restore them to their natural size. Whatever benefit may result from it is due solely to its action on digestion and the improvement in nutrition to which it may thus contribute.
The second indication of treatment, the restoration of the dilated air-cells to their natural size, is possible, if at all, only at an early period of the disease or in portions of the lung which have not gone beyond a moderate degree of cell-dilatation. An enlarged space formed by the fusion of several cells cannot be lessened in size by any means, medical or mechanical, and the loss of respiratory power from the destruction of the cell-walls in which oxygenation is effected does not admit of permanent relief. Where, however, such destruction has not yet taken place and distension is not extreme, there is reason to believe that a return of the cells to their natural size may in some cases be accomplished. The inhalation of condensed air has been recommended with this view; and no doubt good may result from it, due chiefly to the retardation of the breathing and of the heart's action which it occasions, while dyspnoea is relieved by the larger supply of oxygen taken in at each inspiration. This improvement in respiration causes more complete tissue-metamorphosis, and thus aids nutrition and all the functions.
Still greater benefit is to be derived from the exhalation into rarefied air—a measure which acts upon mechanical principles, and has been found to give relief not only to the symptoms of emphysema, but to the organic disease itself; for the retention and stasis of the residual air, which is far larger in amount in emphysema than it is in health, serve at once to keep up the dilatation of the cells and to increase the dyspnoea; and therefore any means which will effect the withdrawal of this air will favor the return of the cells to their normal size, and at the same time relieve the dyspnoea. This benefit is accomplished by the method of expiration into rarefied air, which acts by suction—or pneumatic aspiration, as it may be termed—drawing out the air from the distended vesicles, and relieving them of the continual presence and pressure of this air. Better results would appear to be gotten from the conjoint use of the two methods—the inspiration of compressed air and expiration into rarefied air—than from either one alone.
By the persistent use of these means in cases which have not advanced so far as to defy all treatment not only may the symptoms of dyspnoea, cough, asthma, and impaired nutrition be improved, but the size of the chest may be diminished, as shown by measurement; and this can result only from the return of the distended air-cells, in some degree at least, to their normal capacity.
The apparatus best fitted to effect this double purpose is that of Waldenburg, as modified by Tobold.12 The method of using it is simple, and can readily be understood by examining the instrument. It must be said that the most valuable action of this apparatus consists in the withdrawal of the air from the cells which it effects, for this tends to produce an organic change for the better—viz. the diminution of the enlarged cells by a sort of suction; while its other action, the supply of condensed air, gives relief to symptoms mainly. In emphysema the expiratory act is relatively more impaired than the inspiratory, and the apparatus is best adapted to the relief of this greater deficiency. Henry Saltzer, formerly of Germany and now of Baltimore, has recently obtained very favorable results from its use in emphysema, not only as regards the dyspnoea and other symptoms, but also in the way of lessening the size of the chest as determined by measurements.13
12 This instrument is made by Messrs. J. Reynders & Co. of New York.
13 A reference to Saltzer's observations and measurements may be found in Weil's Handbook of Topographical Percussion, pp. 107, 108, Leipzig, 1880.
The third indication of treatment has reference to the complications of emphysema. Of these the most common, and one of the most important, is bronchitis, which is to be treated in the same way as when it occurs as an independent affection. Expectorants to promote and remove secretion and agents to allay cough are very important means, because the retention of secretion and the effort of cough to expel it cause a strain upon the air-cells, and thus increase the emphysema. The local use, by inhalation or spray, of opiates, belladonna, hyoscyamus, and other agents of this class, is often most serviceable by giving relief to the cough without disturbing digestion. As bronchitis is in many emphysematous patients a very chronic affection, and is attended with submucous thickening in the bronchial tubes and consequent diminution of their calibre, the iodide of potassium is an agent of special value for its relief. Whether the influence of this remedy is due to a sorbefacient power or to some other unexplained mode of action, there is no doubt of its great value in chronic bronchitis, so that for this complication of emphysema it claims a very high rank among medicines. The rapidity with which relief is afforded to the cough and dyspnoea of bronchitis, and to the asthmatic paroxysms attending it, by full doses of 10 or 15 grains of iodide of potassium at intervals of four hours, makes it probable that its action is partly neurotic in character. It is remarked by Austin Flint, Sr., that when the iodide has effected a marked improvement in the chronic bronchitis he has known the characteristic deformity caused by the emphysema to be notably diminished.14
14 Clinical Medicine, p. 131.
A dangerous symptom which sometimes arises in the course of the chronic bronchitis accompanying emphysema is profuse bronchial catarrh, which may destroy life by producing apnoea, the surface becoming cold and the pulse feeble and vanishing as the patient seems to be drowning in his own secretion. In this condition the writer has in several instances found prompt and unmistakable benefit from the hypodermic injection of hydrobromate of quinia, and he would strongly advise the use of this agent. The solution he has employed is of the strength of 4 grains of the salt to 20 minims, and of this 15 to 20 minims has been the dose given. Under the action of this remedy the pulmonary capillaries would appear to be so toned that further effusion is checked, and the gasping and cyanotic condition has been speedily succeeded by comfortable breathing. For the same symptom Waters advises the use of moderately large doses of turpentine (drachm doses in aromatic water every two hours) on a plan suggested by Sir D. Corrigan of Dublin.15
15 Diseases of the Chest, p. 172.
As bronchitis has so much power to produce emphysema when the conditions favorable to its occurrence exist, and to increase it when already established, everything tending to prevent it is of great importance. With this view the avoidance of cold and wet, and, when practicable, recourse to a mild climate in winter, are advisable.
The attacks of asthma to which emphysematous patients are subject are to be treated in the same way as the purely spasmodic form occurring independently of discoverable organic disease. If the difficult breathing has come on suddenly and the patient is not laboring under advanced dilatation of the heart, prompt relief may be given by a hypodermic injection of morphia; but if the heart is much dilated, this might endanger too great depression. Chloral is generally unsafe for the same reason. The bromides in full doses may be serviceable in the less severe attacks, and the tincture of lobelia in doses of 10–20 drops every fifteen minutes until slight nausea is felt is often of great benefit, as is also the smoking of stramonium-leaves.
The dropsy met with in advanced stages of emphysema may be so prominent a symptom as to require special treatment. Its cause is found in dilatation and weakness of the right chambers of the heart, which result from obstruction to the circulation through the lungs when compensative hypertrophy is no longer efficient, for then these give rise to passive congestion of the liver and kidneys and remora of the general venous system, with dropsical leakage, seen first and chiefly in the lower extremities. Treatment is therefore to be directed chiefly to increasing the tone of the heart; and for this purpose digitalis is most useful, as it is in other forms of cardiac dropsy. The chief indication of its beneficial action is seen in the better action of the kidneys consequent upon the increased impulsive force given to the heart. When acting favorably, marked relief both of the dropsy and the dyspnoea may be obtained from the use of this agent in the dose of 2 to 4 drachms of the infusion or 10 or 15 drops of the tincture every three or four hours. If the stomach should not bear the digitalis, as is sometimes the case, or if it fail to act or lose its power, the fluid extract of convallaria, recently introduced as synergistic with foxglove, may be employed as a substitute for it.
Under similar circumstances, if the patient's strength will admit of it, great benefit will sometimes result from a mercurial purge, by which passive congestion of the portal system may be relieved and the upward pressure of an engorged liver in some degree lessened.
4. Atrophic Lobar Emphysema.
This disease differs from the hypertrophic form of emphysema in the circumstance that the bulk of the affected lungs has undergone diminution from waste or atrophy of their tissue. Absolutely, the lungs may contain no more air than they should in health—they may even contain less—but, relatively, there is an increased amount of air in them in consequence of the diminished amount of the lung-tissue. Such relative increase of air in a given area of the lung may be very considerable from the atrophy and destruction of the cell-walls, the alveoli coalescing so as to form cavities, while the individual air-cells are not dilated. The entire lung, however, is shrunken, the chest-wall correspondingly depressed and contracted, and the thoracic muscles atrophied. The function of the affected lungs is impaired in consequence of their loss of size and the diminution of the respiratory movements. This is of course especially noticeable when exertion is made, while under other circumstances there may be little or no embarrassment of breathing unless the disease is far advanced and has involved a large amount of both lungs. But, in general, this form of disease causes less distress and is a less formidable affection than hypertrophic emphysema. In some cases a mingling of the two forms is found, as when a person the subject of general atrophic emphysema has a local vesicular dilatation developed at the top and margins of the lungs.
The shrunken state of the lungs in atrophic emphysema prevents the heart from being overlapped, so that the area of cardiac dulness is not lessened, as it is in the hypertrophic form; and as the general waste of the system is attended with a diminution of the amount of blood, dilatation of the right ventricle, and consequent dropsy, are not apt to occur, as they are in hypertrophic emphysema.
ETIOLOGY.—Atrophic emphysema is always due to constitutional causes. It is found chiefly in old persons or in those in whom impaired nutrition has produced the degenerative changes of old age. Hence it is described by some writers as senile emphysema or senile atrophy of the lungs.
SYMPTOMS.—Of the general symptoms of atrophic emphysema, apart from those which belong also to the hypertrophic form, the most marked are—first, the lessened size of the thorax; and, second, the character of the dyspnoea, which is not urgent, and is not apt to occur except on making exertion. The blood is lessened in amount from the general impairment of nutrition, and is therefore adapted, so to speak, in quantity to the diminished aërating space. Percussion in general gives exaggerated resonance, from the relative increase of air in the lung and the thinness of the thoracic wall, which thus vibrates more perfectly. In some cases, however, from loss of elasticity in the cartilages of the ribs, the resonance is even diminished. On auscultation there are found somewhat prolonged expiration and, in general, feeble inspiratory murmur—signs which belong also, but in greater degree, to true hypertrophic emphysema, from which, however, the atrophic form is to be distinguished by the contraction of the chest that is seen throughout its entire contour.
In some cases of hypertrophic emphysema there may be, it is true, an appearance of partial contraction of the chest-wall, since where the emphysema has produced a marked bulging of the upper portion of the thorax the part below may seem by contrast to be contracted. But in the atrophic form of the disease no distension is seen at any part of the chest-wall, the whole surface being more or less sunken and contracted. Even in hypertrophic emphysema with distension of the thorax, when the disease has lasted a long time there may be some degree of wasting of the lung-tissue; but this condition does not constitute true atrophic emphysema, which is such from the beginning without any preceding stage of hypertrophy.
DIAGNOSIS.—The diagnosis of atrophic emphysema is to be made by the physical signs studied in connection with the conformation of the chest.
PROGNOSIS.—The prognosis of this affection is hopeless as regards a cure, since the organic change is due to the degeneration of age; yet the disease may continue for years without materially or at all affecting the duration of life.
TREATMENT.—The atrophied lungs can never be restored to their integrity; treatment is therefore limited to the use of tonics and nutriment in order to hold in check the process of waste; and to the relief of bronchial catarrh, which is apt to be attended with profuse purulent secretion. The agents best suited to these two purposes have already been considered.
II. INTERLOBULAR OR EXTRA-VESICULAR EMPHYSEMA.
Interlobular or extra-vesicular emphysema is, as has been previously stated, an affection differing anatomically and pathologically from the form of disease already described. In the vesicular form air is present where it normally belongs, but in undue amount; in the interlobular form it is present where it ought not to be—that is, in the meshes of the connective tissue between the lobules, beneath the pleura, and around the bronchial tubes and pulmonary vessels. These situations may be reached by the air through a rupture of the vesicles, and thus in some cases vesicular may be associated with interlobular emphysema, the rupture having occurred from violent cough; or the emphysematous infiltration may be gaseous, as the result of gangrene occurring during life or of decomposition after death.
DIAGNOSIS.—The presence of air in the connective tissue of the lungs cannot be determined by any signs or symptoms; if, however, it should be discovered in the subcutaneous tissue of the neck, face, or chest, giving rise to puffiness and crackling of the integument, its presence in the areolar tissue of the lungs may be suspected, especially if there be coexisting vesicular emphysema, the air having passed into the mediastinum and thence into the tissue beneath the skin.
The existence of interlobular emphysema is not, in general, of serious significance, as the air commonly disappears from the subcutaneous tissue in a few days; whence it may be inferred that it likewise disappears from the connective tissue of the lung, the opening which had admitted it there having become closed. If present in large amount in the lung-substance, it may, however, increase the difficult breathing of an emphysematous subject by compressing a number of the air-vesicles. Or, again, if the interstitial emphysema be subpleural, the bulla may burst, and the air, escaping into the cavity of the chest, may occasion pneumothorax, or even hydro-pneumothorax, from the resulting inflammation. Such an occurrence is, however, very uncommon.
Even when the diagnosis of interlobular emphysema is established, no treatment is needed or practicable.