Part 3

Though inflammation does not always accompany the sensation of pain, yet the latter, in a greater or less degree, attends inflammatory action; and, perhaps, it is fortunate that it does so. Because, were it not for the occurrence of pain, the patient’s attention would not be directed to the disease; he would continue to use the part as if in health, and the affection would thus be much aggravated. Whereas, according to the existing provision of nature, pain is felt at the commencement of the action, the presence of which the patient is thereby made aware of; and he is compelled to employ such measures for its removal as reason naturally dictates, of which none is more effectual than disusing the affected part. The nerves are thus the safeguards of the various parts of the body in health—their nurses in disease. A part deprived of sensation may be used, even to the destruction of its texture, without producing any impression on the sensorium, and consequently without the animal being conscious of it.

The presence of pain, as a symptom of inflammation, may be easily explained. The connexion of the vascular with the nervous system is very constant and intimate. Their ramifications accompany each other, and are contained in the same cellular sheath; and without the reciprocal influence of each, neither could perform its functions perfectly. By injecting a limb soon after its separation from an animal, and before its vital heat has departed, spasms of all muscles are sometimes produced; showing the intimate connexion between these two systems. This, however, is distinct from the contractions of the muscular fibre produced by the application of stimuli. In the former case, the contractions are universal, and induced through the medium of the nerves. In the latter, the irritability of the fibre is excited.

When the circulation is excited, the nerves accompanying the affected vessels are unusually compressed, and over-stimulated by the circulating fluid, in which, probably, some change takes place, and in this manner unnatural impressions are produced; the nerves themselves are likewise the seat of disease, in consequence of the enlargement of the minute capillaries which permeate them. Over-distension of the coats of the vessels may also be supposed to give rise to painful feelings, independently of any affection of the accompanying nervous trunks.

The degree of pain is generally in proportion to the sensibility of the part when in health; it also depends upon the distensibility of the parts affected, and on the intensity of the inflammatory action. When bones, tendons, &c., which in their uninflamed state are nearly insensible, become inflamed, the pain and suffering are most excruciating, owing to the resistance opposed to the dilatation of the vessels, and the prevention of the effusion by which they naturally relieve themselves.

The kind of pain also varies, in consequence of different modifications in the action causing different impressions on the sensorium. Pain is not always increased in proportion to the natural sensibility of the part; for in some instances the sensibility is rendered much more intense, while in others it is much obtunded.[1]

The last, and, according to some writers, the only unequivocal symptom of inflammation, is _Heat_. In extravasation of blood into the cellular texture, as under the conjunctiva, there is redness, swelling, and occasionally pain; but at first, and unless the action of the bloodvessels be excited, there will be neither heat nor throbbing. In many internal inflammations heat is much complained of; and in Enteritis it has been considered a pathognomonic symptom.[2]

The signs, symptoms, and consequences of inflammation—and amongst others, heat—are modified by the distance of the affected part from the centre of circulation. All actions, healthy as well as morbid, proceed with more vigour in the superior extremities—in the head, the neck, and the trunk, than in the more remote parts of the body; for to the former the blood is transmitted more speedily, if not in greater quantity, and is not so liable to be impeded in its return. Hence an arm may bear up under a severe injury, which, to an inferior extremity, would prove inevitable destruction. The heat, however, of an inflamed part, is generally supposed to be much greater than it really is. The sensation of heat is considerable to the patient, as well as to any observer, whilst the absolute increase of temperature is very slight indeed. It has been proved by the most decided experiments of Mr. Hunter, on the mucous canals of animals, first when in health, and again after violent inflammation had been excited, that little or no variation of temperature can be observed. The elevation of temperature is probably constant, though only amounting to a degree, or even less. As the blood is the source of heat, wherever an increased quantity is circulated, there should, to some extent, be increased heat.

The effects of an incited action of the vessels on the system at large must now be adverted to; or, in other words, that general disturbance in the system which attends inflammatory incitation, and which occurs in a degree proportioned to the power of the exciting cause, and the kind of texture primarily affected. The functions both of the sanguiferous and nervous systems are deranged, producing a state termed Symptomatic or Sympathetic Inflammatory Fever. From some observations of my friend Mr. Gulliver, it is probable that this state is frequently, if not generally, dependent on changes in the blood consequent on inflammation. A sort of decomposition of part of the fluid and vitiation of the remainder; the fibrin being separated and effused into the injured part for the purposes of reparation, while the blood globules are converted into pus in the capillaries, and mixed with the circulating fluid. Thus the presence of pus in the blood may become the proximate cause of fever; but if an outlet to the matter be established, if it be discharged by the occurrence of suppuration in a cavity or on a surface, the case is benefited and the constitution relieved. This points to an important principle in practice. Nature puts it in operation in small-pox, for example—how favourable it is for the pustules to come out, and to what danger is not the patient exposed if they are repelled.

During the paroxysm of inflammatory fever all the secretions and excretions are diminished or suppressed; and hence the hot dry state of the skin, the thirst with foul and dry tongue, the scanty and high coloured urine, and the constipation of the bowels. This last symptom, however, though it may arise partially from the diminished secretion of mucus, yet is often dependent on disturbance of the functions of the brain and nerves. The pulsations of the arteries become rapid and strong, the sanguiferous system being unable to relieve itself by effusion, in consequence of the obstruction of the exhalants.

If the extreme vessels are in any way obstructed, and the general circulation in consequence much accelerated, the internal viscera become oppressed, and are interrupted in their functions; and relief is experienced only when relaxation occurs in the vessels upon the surface of the body. Thus, in any violent and continued exertion, there is a sense of oppression in the chest, and the functions of the encephalon are somewhat disordered, but as soon as perspiration breaks out the relief is instantaneous, and the animal can, without difficulty, persevere in its exertions.

In inflammatory fever, the breathing is often difficult, and the appetite declines; the patient is restless and watchful, and when he does sleep, he is not thereby refreshed. In the more violent cases, the sensorial functions are much disturbed; even delirium supervenes, with violent muscular exertion and convulsions, and may be followed by coma, should the local affection not subside. The delirium attendant on violent diseases and accidents may often be considered a beneficent effect of nature’s operations; for the patient, frequently losing all consciousness of his situation, seems to be under the influence of the most pleasing hallucinations, and is freed from the more lamentable state of severe mental as well as bodily affliction.

Writers on Inflammation have expatiated at great length on _Sympathies_; and these have been divided into, 1st, The Partial—the Remote, the Continuous, and the Contiguous;—Remote, when parts sympathise, though situated at a considerable distance from each other;—Contiguous, when the sympathetic action seems to be produced, in separate parts, merely from juxtaposition;—Continuous, when the action extends in parts which are of similar texture, and conjoined with that which is primarily affected.—2d, Universal, where the whole system suffers along with parts of it. For instance, the whole system is often disturbed by a deranged state of the alimentary canal, and, conversely, the bowels, or the skin, the brain, the osseous or any other of the textures, may suffer from a general disorder.

The system sympathises much more with some parts than with others; and we accordingly find that disorder in one part will give rise to alarming constitutional excitement, whilst in another, a much greater derangement in function and structure will apparently be almost entirely disregarded by the constitution.

_Irritation_ is an effect of sympathy, and differs from inflammation, inasmuch as the functions of the nervous system, and not those of the sanguiferous, are disturbed;—the latter frequently supervenes on the former. Irritation is local, or constitutional. As examples of the strictly local species, may be mentioned that peculiar and dreadfully annoying sensation produced in the alveoli by the presence of a diseased tooth, or the irritation caused by ascarides in the rectum, or by stone in the bladder.

But, from this action being dependent on the nervous agency, irritation is frequently produced in a part remote from the source of the action. Thus, if an irritating cause of any kind be applied to the origin of a nerve, the effects of the irritation may be evinced in a part supplied by its extreme branches; while, if the cause is applied to the termination of a nerve, a similar action is produced at its commencement, and in parts supplied by nerves from the same origin. Thus, disease of the hip-joint causes pain in the knee, whilst dentition in children not unfrequently produces fatal effusion at the base of the brain; and again, irritation at the neck of the bladder frequently gives rise to pain in the feet.

Local impressions, injuries, or irritations, though apparently of little importance, frequently produce irritation which affects the whole system, and is therefore termed _constitutional_. Syncope sometimes follows the passing of a bougie along the urethra. We meet with too many instances of constitutional irritation following severe injuries or operations, especially if attended with much hemorrhage. In general, there is considerable prostration of strength; the patient is anxious and restless; his sleep is disturbed; the pulse is weak and fluttering, occasionally intermittent; the tongue is white and loaded; the appetite is gone; the stomach rejects the little food which the patient is able to take; he is startled and annoyed by the slightest external impression. At this period of the disorder, rigors generally occur, and are followed by a sense of heat, and by perspiration; then the above symptoms gradually decrease, and the patient recovers; but in certain instances his breathing becomes quick and somewhat oppressed, attended with a peculiar spasmodic elevation of the nostrils; all the secretions are diminished, the intellectual functions become impaired, and there are occasional convulsive twitchings; coma supervenes, preceded by a low muttering delirium, and followed by death.

This action, as well as every other, is much modified by the importance of the part which is the source of the action, and by the constitution of the patient. It is more severe in children than in adults. The affection will be more fully detailed, when treating of local injuries, and the management of patients after severe operations.

The _Causes_ of Inflammation come next to be considered; and first, of the proximate cause or theory. The different states of the Vessels, in their healthy and in their incited condition, have given rise to much discussion. In the first place, considerable difference of opinion exists as to the relative share which the heart, the larger arteries, and the capillaries, have in propelling the circulating fluid in a state of health. Some physiologists are inclined to attribute the principal power to the heart, the blood being propelled and returned, according to them, almost entirely by the vis a tergo; while they suppose that the arteries possess merely a degree of elasticity or tonicity. Considering the arteries as elastic tubes, performing an indispensable part in the propulsion of the blood, we will now briefly consider their state in inflammation.

Passing over the different theories of error loci, spasm, &c., which have at various times been entertained, let us first examine the condition of the capillary vessels, for these are primarily and principally concerned. In inflammation, the balance of the circulation is destroyed, but a diversity of opinion has existed as to the precise nature of the change which occurs. It has been supposed, and perhaps correctly, that the circulation is, in the first instance, much accelerated in the capillary vessels of an inflamed part; but it has been satisfactorily proved by experiment, that, after inflammation is fairly established, the blood circulates more slowly than in the healthy state of the vessels. There appears, in fact, to be, as insisted upon by some writers on the subject, a state of excitement, then of collapse, followed, if the life of the part is not destroyed, by reaction. When a part is stimulated, the circulation is accelerated, and a greater quantity of blood is transmitted by its vessels: if the excitement is speedily removed, they recover themselves, though perhaps a little dilated, and no inflammation ensues. If, for instance, a foreign body of any kind gets entangled betwixt the upper eyelid and the bulb of the eye, and it is permitted to remain a few moments only, redness of the whole surface of the conjunctiva takes place, but it is transitory, and disappears entirely some short time after the extraction of the foreign body. If, however, it is permitted to continue longer in contact with this sensible surface, the membrane reddens more and more, and becomes thickened. Violent pain, with discharge of tears, and alteration of the secretion from the mucous surface, take place, ophthalmia is, in fact, established. If the exciting cause is applied for a sufficient length of time, the extreme vessels lose their contractility, they are weakened, become dilated, and the contained blood circulates slowly. When inflammation is fairly established in a part, the capillaries become considerably dilated, and the blood is often completely stagnated in the inflammatory point. In the circumference of this focus, it is accelerated as formerly noticed: the blood is probably stagnated for two or three days in the capillaries and in the contiguous cellular tissue, when the action is at all violent. It, however, begins to move again; it loses its colouring matter, while stagnated; the fibrin is assimilated to the neighbouring parts, or rather effused, so as to cause the thickening, and the blood globules have possibly undergone a change, and been converted into those of pus. If the disease be of a limited extent, and without breach of surface, they are carried into the circulation very gradually, and in such small numbers as not to produce injury to the health; otherwise the contamination of the blood by a large quantity of pus causes inflammatory fever. It is probable that the permanent dilatation occurs in consequence of the larger vessels in the immediate vicinity being incited, and propelling more blood into the minute capillaries than they can readily return into the corresponding veins; and in consequence of so great a degree of distension being produced, the vessels are incapable of again speedily contracting; the blood, also, from being stagnant, becomes of a darker colour. The larger trunks propelling blood into the distended and comparatively inert capillaries, which are incapable of transmitting into the veins the same quantity of fluid which they receive, will cause the throbbing or pulsating sensation. The blood circulating in the parts around is sometimes apparently changed in quality; it is redder, flocculi appear floating in it, and the globules disappear. These last may have been broken down, or partial decomposition may have taken place from a loss of vital power in the vessels themselves.

The blood globules are, perhaps, merely compressed; for whenever motion is produced in the fluid, they speedily reappear. Fresh globules also find their way into the affected capillaries from neighbouring vessels. The alteration in the component parts of the blood has been supposed to depend upon the previous state of the inflamed vessels in which it is contained: it is said soon to reassume its natural appearance, when brought into a healthy vessel, and reference is made to experiments on the web of the frog’s foot. When once altered, it is, however, questionable if the blood ever reassumes its natural appearance; of course the blood which takes the place of that which was stagnated in the capillaries will be natural. If there have been extensive inflammation, and therefore much altered blood, one of two things will happen, viz., inflammatory fever and its consequences, or the discharge of the offending matter (the altered blood) as pus. We may also conclude that the blood of an inflamed part undergoes chemical changes; for when the part becomes gangrenous, the blood then loses its red colour, and assumes a yellowish-brown hue, from the absorption of its colouring matter, which necessarily implies an alteration in its chemical constitution. It seems not unlikely, that the change which is early observed in the appearance of the blood of an inflamed part is the commencement of a chemical process, which, if the vessels do not regain their contractile power, terminates in the total destruction of the ordinary properties of that fluid. It is probable that the more modern speculators in medical science have paid too little attention to the state of the fluids, and to the fact that, when diseased action occurs in a part, its secretions and supplying fluid are very considerably changed.

But the blood in inflammation also undergoes a change, observable after its removal from the circulation, and especially when the system sympathises with the part affected. The blood, it is generally believed and stated, does not coagulate so quickly as in the natural state, or else, it is said, the red globules, being increased in specific gravity, fall rapidly to the lower part of the containing vessel, so that a yellowish crust appears on the surface of the crassamentum or clot; and this appearance is termed the inflammatory or buffy coat. The blood extracted from the veins of a patient labouring under inflammatory fever often appears to coagulate very quickly; but it contains an unusual proportion of fibrin. In certain states of inflammation, this crust is also much contracted, so that its marginal circumference is at a considerable distance from the sides of the containing vessel; its margins also are elevated and inverted; its upper surface is smooth, whilst the under adheres firmly to the coagulum; and in this state the blood is said to be cupped, as well as buffed. The appearance of the buffy coat is not peculiar to the inflammatory state, but is apparently dependent on hurried circulation, however occasioned. It frequently presents itself in blood removed from the circulation during pregnancy, and in several other conditions of the system, apparently altogether unconnected with inflammatory excitement. In these circumstances, however, the contracted or cupped appearance of the coagulum is hardly ever observed. An ignorance of the above fact leads to dangerous practice, inasmuch as certain practitioners will bleed, and continue to bleed, for very equivocal inflammatory symptoms, conceiving themselves fully warranted in so doing by the presence of the buffy coat. This coat is often not so apparent in the blood first drawn as in that afterwards abstracted.

In inflammation, as was formerly remarked, a greater quantity of blood not only flows into the capillary vessels, but it also escapes from them, or is extravasated. This may occur with or without rupture of the vessels, and to a greater or less extent, according to the violence of the action, and the texture of the part.

When local inflammatory action exists to a considerable degree, the general circulation is more or less disturbed. The heart, and the larger vessels supplying the capillaries, which are more immediately concerned in the local action, subsequently sympathise with the part affected, and, acting with greater vigour than usual, propel the blood into the extreme branches; so that the inflammatory excitement may be said to be gradually communicated by the continuous sympathy, till the whole sanguiferous system becomes subject to its influence. The degree of this general excitement depends greatly on the texture and function of the part primarily affected.

The term _Passive_ Inflammation has been applied to that state in which the larger vessels are not excited, or have ceased to sympathise with the capillary branches. The term _Chronic_ Inflammation is properly limited to the consequence of the acute inflammatory action, the part remaining turgid and swollen, the vessels over-distended with dark blood, but with little or no pain, and without heat or throbbing. _Congestion_ is also employed to denote fulness of the vessels, large as well as small, when no sign of excited circulation, or of decided inflammatory action, has occurred. It is most frequently used, however, when describing the condition of an internal organ. An over-distention of a particular set of vessels may certainly exist (as a consequence of inflammation, or altogether unconnected with it), unattended with inflammatory action. These two states ought to be carefully distinguished from a similar condition of the vessels, attended with inflammation; for practice, which would be beneficial in the one case, is highly prejudicial in the other, and lamentable examples of the non-attention to this distinction are every day observed.

It may here be mentioned, that some have denied the existence of vitality in the blood; and to some minds it may, perhaps, be difficult to conceive how a fluid should be possessed of this principle. But no one can either doubt or deny that the blood, in its distribution, in its manner of receiving increase, in the secretions furnished by it, and in its various morbid changes, is governed by certain laws and principles which cannot be explained by those of chemistry or mechanics, but must belong to some other power. It is allowed, and has been promulgated by all authors, that the blood is one of the most active agents in the animal economy—in repairing waste, in affording peculiar fluids necessary in that economy, in supplying organs with materials for carrying on their functions, &c.; and yet all this, according to some, is accomplished by a dead animal fluid; no one can plausibly object to the laws by which the blood is governed being referred to the power of life, and to their being called Vital Principles.