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 {237}
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 Stokes[4] 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 Waters[5] 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.
[Footnote 4: _Diseases of Chest_, 2d ed., p. 173.]
[Footnote 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.
{238} 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 {239} 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 {240} 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, Rokitansky[6] 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.
[Footnote 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.
[Footnote 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 {241} 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]
[Footnote 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.
[Footnote 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 {242} 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.
[Footnote 10: _Diseases of the Chest_, p. 156.]