"In the case of the liver, which is commonly considered, when in a scirrhous or enlarged state, to be the seat of these mechanical obstructions, and thus, to be the cause of abdominal dropsy, we have no satisfactory instance yet shown to us, of any such precise condition of that organ. There are, indeed, numerous instances of abdominal dropsies, in those labouring under a scirrhous or enlarged state of the liver; but there are also, numerous examples of such states of the liver, as well as of the spleen and other organs, without any such effusion; and in many cases, when such effusion has taken place, it has been carried off by the natural passages or by tapping, without any return of the dropsy; and yet, without any visible change in the structural condition of the liver."
Dr. A. further remarks, that if the cause were mechanical and existed in the liver, the effect should be constant; which, however, is not the case. Besides, were this mechanical cause necessary, how could we account for the appearance of abdominal dropsy, where there is no disease of the liver, or in other cavities, where no mechanical cause is asserted to be present, and where the remedies by which the cure is effected, have no relation to such causes? Again, if the discharge depended upon a mechanical cause, the water should in every case be of a uniform fluidity, and the progress of its accumulation likewise uniform; so that the operation of tapping should have no tendency to induce a more rapid refilling of the cavity. Yet, the contrary of all this is a subject of daily observation. In addition to this, Dr. A. calls the attention to the fact, that in experiments, in which obstruction has been artificially made, by tying the vena cava for example, the experimenter has committed an error, in reasoning from the lower animal to man—assuming, that as ascites had arisen in dogs, it would in like manner have occurred in human subjects.
"But there was an effect, here overlooked, which was to be expected to take place in the abdomen of the dog, from the injury done to the surrounding parts by the operation itself, and which would be quite independent of any effect arising out of the experiment. In the human subject, the effect would be the highest form of inflammation, by which coagulable lymph or pus would be poured upon the surface of the peritoneum. There would, therefore, be inflammation excited in the abdomen of the dog; but as the lower animals are less easily acted on than man, the inflammation would in this case be in a lower degree. But every degree of inflammation has its particular product. The highest occasions a discharge of pus, whilst the lowest, when seated in a serous membrane, is a larger portion of its proper serous fluid. This, therefore, might be the product of the inflammation, which was produced incidentally by the experiment in the abdomen of the dog; and it would be just as reasonable to regard the coagulable lymph in the human subject, which would result from such an experiment, as an effect of the mechanical obstruction, as to consider the fluid effusion in the dog to be so."
In respect to those instances of diseases of the liver, connected with ascites, in which, in addition to its other morbid states, a partial occlusion of the vena portæ, by the effusion of coagulable lymph into it, is said to have existed, our author remarks, that they are very few in number, occurring, perhaps, in one out of several hundred cases of ascites with hepatic disease; and that we are justified, from analogy, to assume, that any obstruction given to the circulation by diseased vessels, would be quickly relieved by the enlargement of the anastomosing branches, and that no effusion of water into the abdomen would result from it. After referring to some cases, related by the late Mr. Wilson, in which the vena cava was completely obliterated, and no effusion took place; and some cases of morbid condition of the heart of an analogous kind, by which the course of the circulation became greatly obstructed, and yet, without being followed by effusion; our author concludes, that from these facts and others, to be presently noticed, it appears evident,
"That the dropsical effusion, in whatever part it may be seated, does not arise from any want of tone in the exhalant or absorbent system, or from a mechanical obstruction in the liver or other viscus; but, that it proceeds from a morbid action in the cellular or serous tissues, and that this action, as we shall now proceed to show, is allied in its nature to inflammation."
In support of this opinion, Dr. Ayre remarks, that all the phenomena belonging to cases of watery effusion, met with under one or other of the forms of inflammation, are common to those of dropsy. Thus the fluid, discharged under the cuticle in erysipelas or in inflammation induced by heat or a blister, or in cases of pemphigus, is a secretion, and resembles in all respects the fluid found in dropsy. In some cases of acknowledged inflammation, the fluid effused is found to vary greatly in its degree of tenuity, so as to be sometimes of quite a viscid nature. The same circumstance is met with in dropsy; the fluid of which varies sometimes in different forms of the disease, and at different periods in the same patient. With regard to the absence of pain, in ordinary cases of local or general dropsy, which, in the minds of many physicians, might seem to militate against this view of the subject,—since pain accompanies the inflammation of a blister, Dr. A. very justly says, that the difference is referrible to a different degree of sensibility of the parts affected; that, moreover, in pemphigus there is no pain, and that chronic inflammation of the serous membranes is little painful.
That the morbid action producing the effusion is only a modification of inflammation, our author thinks may be further shown by the fact that it obeys the same laws—being translated occasionally, like it, from one part of the body to another. On this subject, Dr. Ayre makes the very pertinent remark, that in these cases, the fluid alone has been thought to be translated; but that the metastasis, is without doubt, exclusively of the action which produces the serous discharge. Analogous also to what occurs in inflammation, especially of the erysipelatous kind, the action occasioning the effusion, as seen in anasarca, commences at a given point, and gradually extends from thence in a continuous course. It ought also to be noticed, that the results of common inflammation vary according to the intensity of the cause; the lowest degree of it, occasioning an increase in the quantity of the proper fluids of the part,—a higher degree, yielding for its product coagulable lymph, and a still higher one producing pus. All these several products of common inflammation, are more or less remedial of their cause; or in other words, are the immediate means of the cessation or abatement of the inflammation which produces them. This same power is likewise a property, though in a much less degree, of the hydropic effusion, when the inflammation which produces it, is idiopathic; or in other words, not created by a visceral or other disease, or some particular excitement of the general system, as is seen in cases of anasarca.
"And here," continues our author, "it may be proper to remark upon a common error, committed by those, who, mistaking the nature of the action which produces the serous effusion, look in the post mortem examination, for some of the common signs of an inflammation having existed; and who conclude, upon not finding such, that the water was derived from some mechanical or other cause foreign to the true one. But in the higher forms of abdominal inflammation, the products are pus or lymph, and these are found upon the surface of the peritoneum, with sometimes a thickening and discoloration or ulceration of its substance; whilst in the lowest form of that increased action to which the serous membranes are subject, the only product is the serous fluid, and there can be, therefore, no visible alteration produced by it in the structure of the serous tissue."
"By the hydropic or serous inflammation, obeying the same laws which govern the other degrees of common inflammation, it follows, that upon a higher excitement being superinduced upon it, the serous effusion should cease. This, therefore, is found to happen in every case, where such higher excitement is brought on. This increased inflammation is sometimes occasioned by design or accident, and at other times, it occurs in the natural and progressive course of some disease, formed within the cavity, which is the seat of the dropsical effusion."
This is exemplified in the effects of the operation for the radical cure of hydrocele; or in the operation of tapping in some cases of ovarian dropsy; or even in some instances, of ascites from chronic inflammation of the liver, spleen, mesentery, &c. In all these cases, the serous membrane, which directly or indirectly was affected to a sufficient degree to occasion a serous effusion, takes on, from the extension of a visceral disease, or from some other cause, a higher degree of inflammation—lymph is thrown out, and the cavity becomes obliterated.