neither bronchial spasm nor tonic contraction of the diaphragm is
capable of explaining why catarrhal secretion should come on at the
close of an attack in which at the commencement there was no catarrh,
attributes the phenomena of asthma to sudden swelling of the bronchial
mucous membrane, the result of dilatation of its blood-vessels produced
through the agency of the vaso-motor nerves; thus reviving the
fluxionary theory of Traube. In support of this theory he cites the
result of Von Loven's[18] experiments, which prove that irritation of
the sensory nerves is followed by reflex engorgement of the territory
to which they are distributed. Weber considers that this engorgement of
the bronchial mucous membrane is somewhat similar to the acute swelling
and stoppage of the nostrils to which many persons are subject--a
closure which often does not last longer than a few moments, and which
is attended with increased redness and swelling of the Schneiderian
membrane. The mucous membrane of the nostril and that of the bronchi
being both parts of the respiratory tract, and somewhat similar in
structure, he concludes that the process in the nostrils is analogous
to that which occurs in the bronchi during the asthmatic paroxysm. As
additional proof of the correctness of his hypothesis he cites the fact
that such occlusion of the nostrils is often the precursor of the
asthmatic attack, and in some cases continues throughout the paroxysm.
See investigations of Daly, Roe, Allen, and Hack, further on.
[Footnote 17: "Ueber Asthma Nervosum," _Tageblatt der 45 Versammlung
deutscher Naturforscher u. Aertze in Leipzig, etc._, 1872, p. 159.]
[Footnote 18: _Naturforscher u. Aertze in Leipzig, etc._, 1872, p.
159.]
The idea that asthma is due to swelling and engorgement of the
bronchial mucous membrane appears to have been confirmed by the
tracheoscopic observations of Stoerk.[19] On examining the air-passages
with the laryngoscope, he could see the mucous membrane of the trachea
as far as visible (that is, to the bifurcation) grow red with the onset
of the paroxysm, and resume its normal appearance after the termination
of the attack. He opposes the spasm theory, denies the correctness of
Biermer's conclusions, and adopts Weber's explanation of the asthmatic
phenomena. He agrees with Wintrich that spasm of the diaphragm occurs,
but claims that it results from the tension to which it is subjected by
the inflated alveolæ: the diaphragm being forced downward by the
distended lung, its fibres are stretched, and the result is a tonic
spasm of that muscle. His objections, although well stated, are not
sufficiently conclusive to cause us to accept his opinion in preference
to that of Biermer and other supporters of the spasm theory.
[Footnote 19: _Mittheilungen über Asthma bronchiale, etc._, Stuttgart,
1875.]
{197} Max Schaeffer maintains that asthma is due to bronchial fluxion,
as advocated by Weber, but claims that the hyperæmia is followed by
spasm of the bronchial muscles, the former being primary and the latter
secondary. He also, with many other recent writers, believes that
asthmatic attacks are often associated with pathological conditions in
and about the upper air-passages, such as naso-pharyngeal and
laryngo-tracheal catarrh, polypi, hypertrophied tonsils, and enlarged
cervical glands; all of which act as irritants, which, being
transmitted through the neighboring nerves to the vagus, induce the
bronchial spasm.
Among the older and discarded theories is that of Bree, who in a work
published at the commencement of the present century expressed the
opinion that the dyspnoea of asthma was simply an effort on the part of
nature to rid the bronchial tubes of an irritating substance supposed
to have accumulated in them previous to the attack. He believed that
this materia peccans was thrown out with the expectoration which occurs
toward the close of the attack. He regarded the violent efforts made by
the respiratory organs to expel this offending substance from the
bronchial tubes as similar to the tenesmus of dysentery or the painful
contractions of the bladder when irritated by a rough calculus. Bree
was unable to define more clearly the nature of this offending
substance, but of late years another writer, Leyden,[20] has discovered
in the sputa of asthmatics certain peculiar crystals to the irritating
effects of which he attributes the various symptoms. These crystals had
been observed previously by Charcot in the blood of leukæmic patients,
and subsequently by Neumann in the medulla of the bones of patients who
had died of that disease. Leyden describes the expectoration in asthma
as tough, grayish-white, and very frothy. Imbedded in a transparent
hyaline mass are a number of small bodies, some thread-like, others in
the form of little plugs or flakes. Under the microscope these little
bodies are found to consist of a mass of brownish cellular detritus
containing large numbers of crystals. These are colorless, octahedral
in form, with sharp points, and vary greatly in size, some of them
visible at once, while others are seen only with the highest powers of
the microscope. Their composition has not been determined, but is
supposed to be a substance resembling mucin. Leyden's idea is that the
sharp points of these octahedral crystals irritate the terminal ends of
the pneumogastric nerve in the mucous membrane of the bronchi, and that
this irritation, being transmitted to the nervous centre, is reflected
back, and thus causes spasm of the bronchial muscles. It seems,
however, that these crystals are not peculiar to bronchial asthma,
having been also found in chronic catarrh and other affections of the
bronchi.[21]
[Footnote 20: "Zur Kentniss des Bronchial Asthmas," _Virchow's Archiv_,
Band liv., 1871.]
[Footnote 21: Not being able to obtain the original paper, the writer
is indebted for the greater part of what he has written in regard to
the Leyden theory to the treatises on asthma by Knauthe in _Eulenburg's
Encyclopædie der gesammten Heilkunde_, and by Riegel in the work
already quoted.]
Of the different theories of bronchial asthma which have just been
presented, that of Biermer, although unsatisfactory in many respects,
offers the best explanation of the pathology and symptoms of that
disease.
PATHOLOGICAL ANATOMY.--Bronchial asthma being a purely functional
neurosis, the organs involved present no anatomical changes specially
characteristic of that affection. It is true that in cases of long
standing, in which, owing to oft-repeated attacks, the air-cells have
become distended and their walls attenuated, we find the lungs in the
condition which will hereafter be described as emphysema, but these, as
well as the evidences of chronic catarrh observed in these cases, are
due to the secondary affections, and not to the primary disease.
As previously stated, a certain amount of hyperæmia of the mucous {198}
membrane of the larynx, trachea, and bronchi may be observed during
life with the aid of the laryngoscope; but whether this condition leads
to permanent tissue-changes observable after death is exceedingly
doubtful.
In the pneumogastric nerve pathologists have as yet been unable to
discover, either at its origin or along its course to the lungs, any
alteration in structure capable of explaining the phenomena of
bronchial asthma.
DIAGNOSIS.--The suddenness of the attacks; the occurrence of the
paroxysm usually in the latter half of the night; the slow, labored
expiration, with the whistling, wheezing sounds which accompany it; the
expectoration of catarrhal sputa toward the close of the attack; the
normal respiration and absence of all signs of disease during the
interval between the paroxysms,--are the features by which a case of
simple uncomplicated asthma may be readily recognized. When these
symptoms are present in their integrity in an otherwise healthy
subject, there is no difficulty in arriving at the diagnosis; but,
unfortunately, the picture is not always complete. The asthma may be
complicated with organic disease of the heart or lungs, while primary
disease of these organs, as well as certain affections of the nervous
system, may produce symptoms closely resembling those of bronchial
asthma, and from which it is very essential to distinguish them.
The following are some of the affections which may be mistaken for
bronchial asthma:
1. Bronchial catarrh may be accompanied with more or less difficult
respiration, but even in its worst forms it never causes the severe
attacks of dyspnoea observed in bronchial asthma, and, as Riegel justly
remarks, the severity of the symptoms in the latter disease are out of
all proportion to the insignificance of the physical changes.
The dyspnoea of bronchitis comes on more gradually, the attacks being
dependent upon a variety of accidental circumstances; whereas the
asthmatic paroxysm usually occurs quite suddenly in the night without
any apparent cause. The cough in bronchitis is severer and the
expectoration more abundant than in asthma; the latter is also
different in quality, becoming purulent as the disease advances,
whereas in asthma it seldom loses its mucous character. These points of
difference and the presence of the other symptoms of bronchitis are
sufficient to differentiate that disease.
2. Emphysema is frequently associated with asthma, either as a cause,
as is believed by many, or as an effect of that disease. It is often
exceedingly difficult to determine whether the emphysema when present
is the cause of the dyspnoea (symptomatic asthma), or whether the
inflation of the air-cells and other symptoms are not the result of the
bronchial spasm: a careful inquiry into the history of the case will
often decide the question. The points of difference between the two
diseases are very similar to those to which we have just called
attention as the distinguishing features between the dyspnoea of
bronchitis and the true asthmatic paroxysm. The suddenness with which
the attack comes and goes, the severity of the symptoms compared with
the insignificance of the local lesions, the absence of dyspnoea in the
intervals between the attacks (in uncomplicated cases), are all the
reverse of what is observed in emphysema. In that disease the attacks
develop more gradually; there is always more or less shortness of
breath, and the evidences of changes in the structure of the lung are
quite marked.
3. Dyspnoea resulting from cardiac disease is often very severe, but
may be distinguished from bronchial asthma by the presence of the
various murmurs and other physical signs by means of which that class
of diseases is recognized. The asthmatic paroxysm, as a rule, comes on
when the patient is most quiet, usually during sleep. The attack of
cardiac dyspnoea, on the contrary, is always brought on or aggravated
by physical exertion, mental excitement, or some other apparent cause.
In asthma the respiration during {199} the intervals between the
paroxysms is quite natural; in cardiac dyspnoea there is always more or
less embarrassment. Pain in the region of the heart, in many cases
quite severe and extending down the left arm, may direct attention to
that organ as the source of the dyspnoea.
4. Spasm of the glottis, croup, oedema of the glottis, tracheal
stenosis, are all attended with more or less violent attacks of
dyspnoea. We are indebted to Biermer for having directed attention to
an important symptom by means of which all these affections may be
distinguished from bronchial asthma. In the latter, and in all other
diseases causing narrowing or obstruction of the finer bronchi, the
dyspnoea is during the expiration, but if the impediment be in the
larger air-passages the dyspnoea will be during the inspiration.
"Dyspnoea during expiration is just as characteristic of narrowing of
the finer bronchi as the same condition during inspiration is of croup
and other forms of laryngeal stenosis." In croup the neck is extended
and the head thrown back. Notwithstanding the violent inspiratory
efforts of the patient, the lungs are but partially filled; the air in
them becomes rarefied, causing a yielding of the less-resisting parts
of the thorax--_e.g._ the supraclavicular space, the lower portion of
the sternum, and adjacent costal cartilages--and a sinking in of the
abdomen. During expiration, which is accomplished quickly and with
comparative ease, the thorax resumes its natural form. In bronchial
asthma, on the contrary, the head is thrown forward, and the shoulders
fixed in such a position as to enable the muscles of expiration to work
to the best advantage. The thorax, instead of sinking in, is expanded
and abnormally round, giving on percussion the peculiar pasteboard-box
sound (Schachtelton) which Biermer has described as characteristic of
inflation of the alveolæ. In croup the sibilant râles are heard during
inspiration, while in asthma they are more pronounced during
expiration.
5. Spasm of the diaphragm is another affection from which it may be
necessary to distinguish bronchial asthma. This rare disease, which is
almost always associated with hysteria, is characterized by a short
inspiratory movement, during which all the muscles of inspiration are
brought into action, and we have the same sinking in of the more
yielding portions of the thorax which has just been mentioned as one of
the distinguishing features of laryngeal stenosis. After this the
thorax remains fixed for a few seconds, the muscles of inspiration
remaining in a state of contraction. There then ensues a quick and
powerful expiratory effort, accompanied by a sound not unlike that of
hiccough; then another inspiration, with a repetition of the above
symptom; and so on until the attack is over. It will be seen from this
description that this affection resembles singultus more than asthma,
and that there is but little likelihood of its being mistaken for the
latter disease.
6. Paralysis of the posterior crico-arytenoid muscles, like croup,
spasm of the glottis, and all other affections which produce narrowing
of the larger air-passages, is distinguished by the dyspnoea being
inspiratory, and not expiratory. The function of the posterior
crico-arytenoid muscles being to enlarge the glottis, the result of
their being paralyzed would be to lessen the opening through which the
air passes to reach the lung; and in viewing the cords in such a case
with the laryngoscope it will be found that the opening is reduced to a
narrow chink. Another distinguishing feature is that the dyspnoea is
continuous, and, unlike bronchial asthma, does not come on in
paroxysms.
7. An affection which, like asthma, comes on in the night during sleep
is the condition known as nightmare, and, like the former disease, is
characterized by labored breathing. To distinguish it, it is only
necessary to awaken the patient, when the immediate cessation of all
symptoms will at once remove all doubt as to the nature of the
affection.
8. Through carelessness or ignorance intercostal neuralgia has been
{200} sometimes mistaken for asthma. Pain along the course of the nerve
and the presence of the points douloureux, which Valleix has described
as characteristic of neuralgic affections, are sufficient to establish
the diagnosis.
9. Embolism of one of the middle or larger branches of the pulmonary
artery is also characterized by great embarrassment of respiration, but
is not likely to be mistaken for asthma by any one at all familiar with
the two affections. The cachectic appearance of the patient, the
intense anxiety depicted on his countenance, the evidence of cardiac
disease or of some affection of the vessels, the weakened cardiac
impulse, the thready and at times irregular pulse, together with
evidences of more or less pulmonary oedema, are sufficient to
distinguish this form of dyspnoea from that of asthma.
PROGNOSIS.--As there is no well-authenticated case of death from
uncomplicated asthma, the prognosis quoad vitam may be regarded as
absolutely favorable. That death never occurs during the severe
paroxysms of asthma may be due to the action of the deficiently aërated
blood upon the respiratory centres, and bronchial spasm, causing
relaxation when the symptoms have become most threatening. The
asthmatic, if his case be incurable, may live for a number of years,
and even attain to extreme old age, but his life will be one of intense
suffering, which becomes more intolerable as he advances in years.
Sooner or later, bronchitis, emphysema, or heart disease is developed,
which in its turn may lead to renal disease and dropsy.
Such is the almost invariable result in middle-aged and elderly
persons; in the young, however, the chances of recovery are much more
favorable. Salter[22] states "that in youth the tendency is invariably
toward recovery, whereas in one attacked with it after forty-five the
tendency is generally toward a progressive severity of the disease and
the production and aggravation of those complications by which asthma
kills." The favorable result in childhood he attributes to the
recuperative power of youth: growth and change, being more rapid than
later in life, enable the system to repair during the intervals
whatever damage may have been sustained during the paroxysms.
[Footnote 22: _On Asthma_, Am. ed., p. 168.]
There is another class of cases in which, owing to our being able to
recognize and remove the cause, the prognosis is quite favorable: thus,
if it has been discovered that the disease is due to some local
influence, change will often effect a cure, and the patient will remain
well as long as he remains in the locality which agrees with him, but
generally relapses if he ventures to return to the place where he first
contracted the disease. The same may be said of that form of asthma in
which the disease is due to some trade or pursuit necessitating the
inhalation of irritating dust or gases: the indications are obvious.
Cases in which the paroxysms have been traced to the presence of nasal
polypi or to a tumor pressing upon the course of the pneumogastric
nerve have been promptly cured by the removal of these growths. In all
these cases it is presupposed that there is no organic disease, for the
presence of any one of the serious complications we have mentioned
would dissipate all hope of cure.
In arriving at a prognosis it is all-important to inquire into the
severity and frequency of the attacks, as violent paroxysms at short
intervals soon lead to incurable complications. It is also essential to
ascertain the condition of the patient during the intervals between the
paroxysms: if at that time he feels well and does not suffer with
shortness of breath, we may infer that as yet no organic change has
occurred; if, however, he complains of more or less dyspnoea during the
intervals, we may safely conclude that some organic disease has set in
and that the case is incurable. Salter attaches great importance to the
persistence of expectoration during the intermissions, regarding it as
indicative of bronchitis, and therefore as an unfavorable indication:
to use his own words, "Spitting is one of the worst signs in asthma."
{201} Briefly, those cases may be regarded as favorable in which the
patient is young and has no inherited tendency to the disease, is free
from the many complications of asthma, and in whom the attacks are
light and occur at long intervals. On the other hand, all cases may be
regarded as unfavorable in which the patient has reached or passed the
middle period of life, has inherited a tendency to asthma, if the
attacks are severe with short intervals, or if he has some one or more
of the secondary affections of the disease.
TREATMENT.--The treatment of bronchial asthma consists of measures to
mitigate and relieve the paroxysms and prevent their recurrence.
_A._ Of the Paroxysm.--A patient suffering with an attack of asthma
will generally instinctively assume the position in which he can use
the muscles of respiration to the greatest advantage, but if found in
the recumbent posture he should be advised to sit up in bed and grasp
the knees with his hands, so as to gain a position which admits of the
more ready entrance of air into the lungs. In severe cases it is better
to have him rise from the bed and support the head with the hands, the
elbows resting on a table in front of him. An ingenious
suspension-apparatus, intended to promote the comfort of persons
suffering with severe dyspnoea, was extensively advertised several
years ago, and may possibly still be furnished by the
instrument-makers. It consists of a cross-piece suspended from the
ceiling, to which straps are attached for supporting the shoulders
without in any way pressing upon the chest; it is also provided with a
band for the support of the head. In severe and protracted cases, when,
notwithstanding the patient's exhaustion, he is unable to rest upon
pillows, such an arrangement might afford great relief. If not
undressed, the clothing should be so arranged as to interfere as little
as possible with the respiratory movements. An abundant supply of fresh
air is essential, and to secure this one or more windows should be
thrown open.
Asthma being the most capricious of diseases, remedies often acting
differently in each individual case, it is well before commencing
treatment to follow Salter's advice and inquire of the patient what
remedy has usually afforded the most prompt relief in previous attacks,
and thus avoid the risk of prolonging suffering by using remedies
which, although apparently indicated, may in his case, owing to
peculiar idiosyncrasies, prove to be useless or even injurious.
We have seen that the disease is often due to some special cause, such
as the inhalation of an atmosphere laden with the perfumes of certain
flowers, with ipecac, dust, etc., the removal of which, if practicable,
should of course precede all attempts at treatment. The condition of
the stomach and bowels should be inquired into, and if found overloaded
they should at once be relieved, the one by an emetic and the other by
enema.
In the absence of any hint afforded by the previous experience of the
patient the choice of the remedial agent will depend upon the severity
of the attack. In the majority of cases, when severe, no remedy will
afford such prompt relief as the subcutaneous injection of morphia. To
be effective, the dose should be a full one, a fourth to a third of a
grain, either alone or, if there is likelihood of this occasioning
nausea, combined with one one-hundredth to one-eightieth of a grain of
sulphate of atropia. The writer is aware that the use of opium and
other hypnotics in bronchial asthma is discouraged by one of the most
distinguished authorities on that disease, Salter, who claims that they
are not only worthless, but often injurious. He believes that sleep
tends to promote the paroxysm, reflex action being much more active
then than during the waking hours, and that any agent which induces
such a condition is necessarily contraindicated--that, in his opinion,
in addition to exalting reflex action, it acts prejudicially, as "by
lowering sensibility it prevents that acute and prompt perception of
respiratory arrears which is the normal stimulus to those extraordinary
breathing efforts which are necessary to restore the balance." These
objections, although supported by {202} scientific evidence, are
insufficient to cause the abandonment of an agent which in the hands of
others has proved so prompt and efficacious in relieving the terrible
sufferings of asthma, and Salter himself admits that since writing the
above he has had cases in which it has been of signal service. A
serious objection to its use is that the dose has to be increased as
the patient becomes accustomed to its use. In confirmation of its
marked beneficent effects, I give the following extract from
Steavenson's treatise on asthma. Describing his own experience, he
says:[23] "Sedatives and antispasmodics I should consider most
serviceable drugs, but above all in value I should place the hypodermic
injection of morphia. This has never failed to relieve an attack in
myself, and I have never seen it fail in other patients. The objection
to it is that if often used the dose must be increased; but it is
better to increase the dose of morphia than suffer the agonies of
asthma and allow those organic changes in the constitution to take
place which I have described when speaking of the pathology of the
disease. I have now used morphia for five years, but my attacks are so
quickly relieved and so reduced in frequency that I have never yet had
to increase the dose I commenced with--namely, one-sixth of a grain."
[Footnote 23: _Op. cit._, p. 29.]