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that when the breathing is inclined to be asthmatical the dyspncea may be aggravated, and the asthmatic feeling very much increased, by a prolonged expiration; while, on the other hand, the spasm may be broken through, and the respiration for the time rendered perfectly free and easy, by taking a long, deep, full inspiration. In severe asthmatic breathing this cannot be done; but in the slight bronchial spasm that characterizes hay-asthma I have frequently witnessed it. ”It seems as if the deep inspiration overcame and broke through the contracted state of the air-tubes, which was not immediately re-established.
Now all this certainly looks as if expiration favoured, and inspiration opposed, contraction of the air-passages--in fact, I think it amounts to positive proof of it. But I am not prepared to say that the bronchial tubes undergo distinct muscular contractions at each expiration. I think it possible to explain the phenomena otherwise. I think it possible that the diminution of their calibre at expiration may be due to the constant and unvarying tendency of their muscular and elastic walls to contract. This tendency is antagonized and overcome during inspiration, by which the tubes, like the other contents of the chest, are forcibly distended; in expiration this tendency is no longer opposed, and, like the other contents of the chest, they collapse. Still the assumed active contraction of the bronchi is quite consistent with the phenomena, especially those which I mentioned with regard to asthma--that a long expiration, namely, deepens the spasm, while a full inspiration may teniporarily annihilate it. This looks as if bronchial contraction and inspiration were incompatible, and could not co-exist. Still, it would be possible to explain both these circumstances by supposing that prolonged expiration merely suffered the tube more completely to yield to the pre-existing asthmatic spasm, while the distension of expiration was too strong for it and overcame it.
In relation to cough, the opinion has been advanced that the muscularity of the bronchial tubes may, by diminishing their calibre, increase the rapidity of the rush of air driven through them by the act of coughing, and thus increase its expulsive power. If this contraction were general and extended to the smaller tubes, the reverse would be the case, for a smaller stream of air would be brought to bear upon the obstructing material. If, however, it is a circumscribed contraction, confined to the situation of the matter to be expelled, then it would be a veritable adjuvant, and the air would rush through the point of narrowing with increased rapidity, and therefore increased expulsive power, just as narrowing an outlet of water clears and deepens the channel. But the contraction being at the seat of the matter to be expelled, and there alone, is an essential condition to this increase of expulsive power. A little glottis is, as it were, formed there, and the material inevitably driven through it.
But there is a third purpose, I think, arising from this very danger of the access of deleterious matter to the lungs, more important than either of the other two to which I have referred, and which I believe to be the purpose, par excellence, of the muscularity of the air-tubes. It is the guarding the delicate ultimate lung-strueture, the shutting off from the air-cells, and preventing reaching them, any deleterious material that may have gained entrance through the glottis. After having passed the glottis, there is no other means by which the further progress of any foreign matter may be arrested ; and its arrest ere it reaches the pulmonary structure seems as essential to the well-being of the lung as its subsequent expuision by cough. We know, in tact, that very little of the foreign particles contaminating the air reaches the air-cells; that it is almost entirely arrested and expectorated; and we know, too, that the respiration of air charged with any irritating or noxious material, such as the smoke of burning pitch, &c., will immediately produce in many people the symptoms of bronchial stricture.
Another office that has been claimed for the muscularity of the bronchial tubes, is the regulation of the supply of air to those portions of the lung in which they terminate, in the same way as the muscularity of the arteries regulates the blood. supply to the capillaries. We can easily understand how, when one lung or one portion of a lung is injured, a relaxation of the bronchial tubes of the other portion would enable them to deliver to it a freer supply of air, and thus capacitate it better for doing double duty. On the other hand, we can imagine how, in certain violent inspiratory efforts, a narrowing of the bronchial tubes would limit the supply of air, and exercise a conservative and protective influence by preventing too great and sudden a distension.
But if we would form a correct idea of the purposes which are stored up in an organ, our attention must not be restricted to its working in health, but must embrace also those exceptional processes that arise in the course of disease—those latent, and, during health, inoperative powers kept in store, as it were, against the emergencies they are to meet-by the possession of which in its different organs, the body becomes not only a self-maintaining and self-regulating, but a self-correcting machine. Have the bronchial tubes any such exceptional office, adapting them to a pathological exigency ? Such a one has been assigned them. It has been maintained that when the smaller bronchial tubes become filled with secretions, as they so commonly do in disease—with mucus, for instance, as in capillary bronchitis; or with muco-plastic matter, as in pneumonia--they empty themselves of it, and pass it on into the larger tubes by a peristaltic contraction. This would be the acquisition in disease of the same kind of action as the ducts of most glands have in health. There are two strong negative reasons in favour of this view. One is, that there is in these minute bronchial tubes an absence of that anatomical peculiarity that would prevent anything like a peristaltic contraction of the larger ones--namely, the flakes of cartilage. The other is, that these ultimate tubes are wanting in the ordinary mechanism of discharge by which the bronchial system keeps itself empty-the vis à tergo, namely, of cough; for, having behind them only so small a volume of air—that contained in the lobule or group of lobules in which they terminate-sufficient explosive force cannot be brought to bear upon the mucus obstructing them—there is no air behind it to drive it forth. The larger the tubes the more effectual cough becomes, because the greater the portion of lung with which they correspond, and the larger the volume of air on which the parietes of the chest exercise their pressure in the explosive expiration of cough. The ultimate bronchiæ, then, being deficient in this power of clearing themselves, we should naturally expect that some succedaneum would be provided, and this we recognise in the peristaltic contraction of which they are probably the seat. Were it not for this, one can hardly conceive by what mechanism they would empty themselves of the materials by which, as shown by the sounds of respiration during life and post-mortem examination, they are so apt to become infarcted.
Now, can we see in these real or probable purposes of the muscular contractility of the bronchial tubes any explanation of the phenomena of asthma, and any clue to the ultimate pathology of the disease? Yes, I think, most clearly. We see that the purpose of this muscular furniture of the bronchial tubes is that they should contract under certain circumstances, and on the application of certain stimuli; and seen by this light we recognise in asthma merely a morbid activity, an excess—of this natural endowment; the tubes fall into a state of contraction, with a proneness, a readiness, that is morbid; the slightest thing will throw them into a state of spasm, the irritability of the muscle is exalted, the contraction violent and protracted, that becomes a stimulus to contraction which should not be, and the nervous and muscular system of the lungs is brought within the range of sources of irritation applied to such distant parts as ordinarily in no way affect them. Any healthy man may have his bronchial tubes temporarily thrown into a state of asthmatic spasm by the inhalation of ammoniacal or carburetted or other irritating gases; but only by such materials, whose exclusion is necessary for the safety of the lung, will this natural asthma be brought about. A greater degree of bronchial sensibility is shown in those cases, by no means uncommon, of what is called “hay-asthma,” in which the stimulus to bronchial spasm is the effuvium of hay; a stiil greater, in those cases much rarer, in which the emanations from ipecacuan powder will at once give rise to asthma; a still greater in that numerous class of cases of asthma in which the disease is called into activity by certain atmospheric peculiarities which are altogether inappreciable, as where an attack of asthma is inevitably brought on by going to a certain place, living in a certain house, sleeping in a certain room. All these cases fall strictly under what we may call the formula of health; they are physiological, they are instances of the con. traction of a muscular tube in obedience to stimulus applied to the mucous membrane that lines that tube; the nervous system engaged is the intrinsic nervous system of the tubes, its own ganglia and perceptive and motor filaments, as in csophageal deglutition or intestinal peristalsis; the error is merely a morbid exaltation of a normal irritability. But there are other cases in which the error is more than this, in which the nervous apparatus involved in the phenomena is abnormally extended; in which certain outlying and distant parts of the nervous system are the recipients of the stimuli that give rise to the bronchial spasm, as in those cases to which I have referred, where an attack is induced by an error in diet, a loaded rectum, the application of cold to the instep, mental emotion; in which the gastric filaments of the pneumogastric nerve, the sympathetic, the cutaneous nerves of the foot, and the brain, are respectively the recipients of the stimulus that gives rise to the bronchial contraction. In the former class of cases the bronchial spasm takes place in obedience to the wrong stimulus applied to the right place; in the latter, place and stimulus are alike wrong; the relation of the asthma to its cause is in the one case immediate or primary, in the other, remote or secondary,-mediate, through the intervention of some part of the nervous system extrinsic to the lungs.
In what, then, does the peculiarity of the asthmatic essentially consist ? Manifestly, in a morbid proclivity of the musculo-nervous system of his bronchial tubes to be thrown into a state of activity; the stimulus may be either immediately or remotely applied, but in either case would not normally be attended by any such result. There is no peculiarity in the stimulus, the air breathed is the same to the asthmatic and the non-asthmatic, the ipecacuan powder, the hay effluvium, is the same in both; nor, probably, is there any peculiarity in the irritability of the bronchial muscle ; the peculiarity is confined to the link that connects these twothe nervous system, and consists in its perverted sensibility, in its receiving and transmitting on to the muscle, as a stimulus to contraction, that of which it should take no cognizance. In those cases where the spasm is produced by some irritant applied to the air-passages themselves, this perverted irritability is confined to the bronchial nervous system. The exact seat of the perverted nervous action in those other cases where the stimulus is remote, is more doubtful. Take, for instance, that case in which cold water thrown on the instep immediately produced asthmatic dyspnea. Was the cerebro-spinal nervous system in fault here? Did it transmit to the pulmonary a morbid stimulation, or was the fault, as in the other cases, confined to the pulmonary nervous system-to its being morbidly affected by a nervous impression perfectly normal? These are questions that in the present state of our knowledge it would be difficult or impossible to pronounce upon. At any rate, it is clear that the vice in asthma consists, not in the production of any special irritant, but in the irritability of the part irritated.
These considerations, I think, tend to rationalize our notions of asthma, and to impart at once an interest and an order to its phenomena.
On the Theory of Inflammation. By James Hinton, M.R.C.S.
INFLAMMATION, being the most frequent form of disturbance in the animal body, haş received from pathologists the largest amount of study. By observation and experiment its phenomena have been traced from first to last
. Yet the word conveys to us still but an indefinite meaning; the relation which the changes implied by it bear to each other has not been distinctly grasped. The senses have contributed their part, but the mental element is defective. We still wait for that true knowledge which consists in the recognition of order and mutual dependence; and our efforts must continue until we are able to place before our intellectual sense the observed phenomena in a rational and necessary sequence.
Nor is there in such an attempt anything unreasonable. The links of necessary causation must exist, and a right knowledge of them must be simpler and more conformable to reason than hypotheses constructed in ignorance. We seek the relation in which certain observed processes stand to each other, the rational bond between them. In a word, we require a dynamic view of inflammation. Some progress in this direction has indeed been made in the proposition now so generally held, that inflammation is “an altered nutrition." Unquestionably this is so far good. It recognises in inflammation a process, and excludes therefore the idea, which is so apt to suggest itself to us in relation to all that is not understood, of a specific entity. But this expression can hardly be said to advance us far on the road to a positive knowledge. If we may, on the one hand, affirm it to be true, must we not, on the other, admit it to be a truism? What is the amount of information it conveys to us which we did not previously possess ? It tells us that inflammation is a diseased or perverted state of life, but are we not apt to think that it tells us much more? Does not that unknown term “nutrition" stand in our thoughts for some definite addition to our knowledge ? Does it present itself to us so clearly as it should do that if the meaning of nutrition be so large, and we know so little of its nature, it is but a form of words to say that inflammation is an altered state of it?
All writers on inflammation have recognised in it processes of two opposite characters and tendencies. Mr. Paget classifies them into those that are productive, and those that are destructive, and the distinction is broadly obvious. Into the ordinary conception of nutrition itself indeed both these processes enter; it is regarded as including two opposite actions or series of changes-- growth and decay. But this oppositeness of action is even more marked in inflammation than in health. In an inflamed part we may see a structure decomposing, not in invisible molecules, or by mere interstitial removal of its elements, but dying in large masses, while all around it the evidences of vital action, of the impetus towards growth, are seen in more than ordinary energy. Is there any intimate relation between these opposite actions; may inflammation consist in either alone; or, if both be essential, what is their connexion
That an increase of both processes, the decay and the vital action, is necessary to constitute inflammation, appears when we consider the distinctive characters of that affection. It differs from were increased decay, as primary gangrene or atrophy, on the one hand; and from mere increase of vital action-hypertrophy, repair, or developmentupon the other. Its peculiar characters involve at once an abnormal increase of destruction and of growth.
If, then, both these changes be essential to inflammation, can there be traced between them any other connexion than that of co-existence? Are they related as cause and effect? Which is the starting-point of the morbid process?
I answer: they are related as cause and effect; the increased decomposition is the starting point; the increased vital action is secondary and dependent.
The first proof of this position is found in the nature of the causes by which inflammation is induced. All of these, it has often been remarked, are such as clearly tend to lower the vital power or to produce actual destruction of the parts on which they act. In every case in which the origin of inflammation is distinctly traced, the starting-point is found to be in fact an anti-vital change.
And this practical evidence is reinforced by the most cogent theoretical considerations. Can we represent to our thonghts any clear idea of a primary abnormal increase of the vital or formative action that shonld be inseparable, as inflammation is, from a concurrent increase of decay? And this increased decay, not such as attends and is subservient to increased growth, but of so disproportionate an amount as almost always to result in a lessened vitality of the affected part. Is it not a contradiction that an approximation to death should be the result of an increased life? It is not inquired now how such a primary increase of the formative action should arise, and especially in such circumstances of debility and depression as most favour inflammation, because that subject will be considered hereafter in tracing the relation between inflammation and adventitious growths; but there is a direct bearing on the question in the fact that inflammation arises in tumours then first when decay begins in them. It is incompatible with the increased formative action which produces them; it is a constant attendant on their disintegration,
Connecting thus the two series of changes, destructive and formative, as cause and effect, both may be understood. For the increased formative action some cause is demanded, some additional and locally acting force to which it may be ascribed. This demand is fulfilled by the increased decomposition, which is a known source of force, and which is itself sufficiently accounted for by the tendency of all organized substances to undergo decay. The abnormal decomposition is referrible to known and sufficient causes, and itself supplies a cause for the abnormally increased activity of the formative process. For not only is decomposition of the tissues (a change belonging to the class of chemical actions) a recognised source of force as such, and thus capable of acting as a stimulus upon the vital activity of adjacent tissues, but it is shown by well-known facts to be immediately concerned in the production of the formative action. Such facts are the liquefaction of certain portions of the embryo as conditions for the development of other portions; the decomposition of the food which forms the first stage of digestion; and especially the immediate dependence of the nutrition of any organ upon its functional activity.
Inflammation indeed stands thus but as an exaggerated instance of this normal relation of decomposition and growth: it is strictly correlated to the ordinary processes of life; an abnormal or excessive functional or decomposing change, producing a similar excess of the reparative action. It may seem strange indeed how so natural an interpretation of the facts should have escaped the sagacity of those observers who have especially noticed the intimate connexion between functional activity and inflammation, and who have remarked that excessive function of an organ leads to or becomes inflammatory action by such continuous gradation that the line cannot be drawn between them.
Inflammation is excessive function, with or without qualitative perversions : common in the absence of such perversions, specific when they exist. The term “ function" is here used to signify that disintegrating change of which the functional activity is an indication. In attributing inflammation to an excess in this respect, nothing is assumed but a known tendency, the chemical affinities, which may always be presumed to act when not prevented by opposing force, or absence of the requisite conditions ; and which are therefore necessarily brought into play by all that diminishes the perfection of the vital state. From the operation of these forces all the main phenomena of inflammation may be traced in a consequent series, and no recourse is necessary, as upon the hypothesis of a directly increased vital action, to mysterious, or at least to unknown, powers.
The twofold nature of the processes concerned in inflammation has been one chief source of the difficulty that has invested the subject; these processes not being seen in their true relation, nor recognised as corresponding, in respect to that relation, to the healthy life. Two opposite views have been maintained by different writers, each with