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ance of thoracentesis has been advised and practiced as a common and harmless measure for the removal of intra-pleural serum, the security against the entrance of air being the principal assigned reason for the safety of the procedure, while other sources of danger have been quite generally ignored.
Although a few authors, as Dr. Anstie, in Reynolds's "System of Medicine," and Fraentzel, in Ziemssen's "Cyclopædia of the Practice of Medicine," have advised the exercise of some caution in resorting to the operation, with care and moderation in the procedure itself for fear of ultimate injurious effects, particularly the production of pyothorax, by the great majority of recent writers to whose works I have access, no mention is made of this danger. While by a few some general cautions are given, the tone pervading the literature of the subject has seemed to encourage the idea of the innocuousness of the operation, and in many instances I have noted that no reference was made to injurious results. Beginning with the two hundred and fifty or more cases given by Bowditch, and adding other reports, the operation is shown statistically to be safe; although, in quoting from these lists, the care that had been exercised in selecting cases needing the operation and the indications and rules relating to the amount of liquid to be withdrawn are omitted. The only precaution generally enforced has been to suspend the operation "when the patient complains of a constricting pain at the epigastrium," or dyspnoea is produced. It seems evident to me that, when these symptoms result from the operation, the safety of the patient has been jeopardized; for their presence indicates a profound disturbance in the position and relation of the thoracic organs, and, consequently, some plan should be adopted by which the operation shall cease prior to their production.
The rationale of the matter has seemed to me to be the following:
A consideration of the pathology of pleuritis should give due prominence to the condition of vascular supply of the immediate surface of the pleura. Whatever our views may be concerning the migration of the white corpuscles from the
blood-vessels, the active division of pre-existing cells in and at the surface of the tissues, the introduction of disease-germs from without, and other questions in minute pathology connected with suppuration, it is an accepted fact that, soon after the development of pleuritis and the occurrence of some liquid effusion, there exists on the surface of the pleura more or less fibrinous material, the future history of which is variously determined by the progress of the disease. It may either be absorbed, at least, in a great measure; it may increase to a considerable thickness and result in plaques of scar-like tissue; it may enter, more or less directly and permanently, into bands of union between the opposing surfaces; or it may be a contributory element in determining the development of pyothorax. Immediately beneath the adherent layers of this fibrinous material, the nutrition of the pleura is modified, the vascular supply is increased, and apparently an effort is made to organize the new formation by the extension into it of blood-vessels. At all events, whether the vessels at an early date be new or not, the blood circulating near the surface of the pleura, and particularly beneath the layers of fibrin, is contained within vessels having fragile walls, and the conditions, therefore, are favorable to rupture if the intra-vascular pressure be increased. In considering the mechanical effect of aspiration, this condition of the vessels should be kept prominently in mind, as well as the probable existence of layers and bands of fibrin, which may, even at a comparatively early period, prevent the free expansion of the lung on the removal of the liquid.
Having before us a case requiring aspiration, there will be sufficient effusion in the pleural cavity to cause the pressure to be from within outward, or against the free surface of the pleura, and support is thereby given to the fragile blood-vessels; but, when the process of aspiration is begun, this pressure is diminished until, from inability of the lung to move or expand regularly and freely, owing to the plastic material covering its surface or to adhesions limiting its motion in certain directions, if the aspiration be sufficiently continued, the pressure finally becomes from without inward, or toward the pleural cavity. So
long as this force is expended upon the thoracic parietes, upon the expanding lung through the medium of the bronchi, and upon the other organs within the chest, and it does not exceed the pressure proper for the vessels in the diseased pleura, probably no harm would result; but, when the aspiration is carried to a considerable extent, with inability of the lung to readily follow the outgoing liquid, on simple physical principles, a certain part of the aspirating force will be expended in filling the bloodvessels in the pleura, and from their repletion we have a condition which must influence the future progress of the case. If the congestion thus produced be considerable, it must result in more or less transudation into the pleural cavity; while it also may readily be carried to a point resulting in hæmorrhage, as it did in the case I have related, as shown by the color of the liquid removed at the second aspiration. A hæmorrhage thus induced, even if slight, would doubtless modify unfavorably the soluble fibrin contained in the pleural effusion; for pathologists tell us that the addition of blood to such exudations as we are considering promotes the formation of fibrinous masses; but, whether such speculations be of value or not, if we carry our operation too far, we shall develop or intensify one of the physical conditions connected with inflammation; viz., increased vascular supply; and it is not irrational to suppose that we have thereby increased the probability of suppuration.
To a certain extent, an analogy is furnished in the rapid emptying of the urinary bladder when it has been for some days distended by retained urine, in which case it is a matter of common observation to find the second drawing of urine more or less bloody, and even to have the bladder fill with blood, which may coagulate, and this, when no suspicion of direct instrumental violence can obtain, and without the additional influence due to aspiration, as in the case of hydrothorax. Dr. Gouley has strongly insisted on certain precautions to be taken in emptying a fully-distended bladder; and it seems to me that the same reasons apply with even greater force to the removal of liquid from the chest.
The risk of increasing the inflammatory exudations, I be
lieve, can be obviated by removing a moderate quantity of the liquid, this to be left, of course, to the judgment of the operator and to vary according to the object and effect of the operation. When the operation is for the relief of dyspnoea, it should cease promptly on the attainment of that object, and it will probably rarely be necessary to remove more than a pint of liquid; while, if the object be to accelerate delayed absorption, the withdrawal of even a less quantity may suffice, and, from clinical experience, I am satisfied that eight ounces will often be sufficient for one aspiration. Should the removal of so small a quantity not suffice to secure absorption, I should consider the repetition of the operation, even several times, a lesser danger than would be incurred by the withdrawal of a large quantity, while, at the same time, it would give the lung a chance, through the respiratory movements, to modify the bands or incasements which interfere with its uniform and free expansion.
The objections to the aspirator in the hydrothorax of pleuritis do not obtain when the effusion is due to cardiac or renal disease; in which case I can see no valid objection to a complete removal of the liquid, assuming that the operation is demanded and that it is carefully performed; for here the lung is in a condition to follow the escaping liquid, and no leaven of suppurative change is at hand, unless it be introduced through the carelessness of the operator.
I am aware that formidable arrays of successful cases may be and have been presented as illustrating the innocuousness of aspiration in hydrothorax; but it seems to me that this argument is not sound. As well might Keith have pointed to his long and unbroken list of successful cases of ovariotomy and claimed its freedom from risk; but then came the few fatal cases so near together that he reviewed his means and methods and considered seriously whether the measures to which he had ascribed his former success did not contain the principal cause of the recent deaths.
Medicine furnishes many illustrations of the great value of the numerical method in the study of disease and of therapeutic
measures; but all conclusions based upon numerical data should be subjected to a careful criticism as to whether or not the classification has been complete in all its details.
I recognize in the aspirator an instrument of much value, capable of being used with great benefit; but I also see it as an engine of harm, misery, and death, when used injudiciously. It should never be used for the purpose of emptying and leaving empty a non-collapsing cavity. Its operation is so silent, unseen so far as the actual effect is concerned, and at the same time it does its work so strikingly, that the temptation is to go on with the operation so long as any liquid remains. With the inconsiderate use of the aspirator, I believe it has destroyed more lives than it has saved; for every case of successful aspiration is by no means a life saved.
In another field, where it has been quite commonly used (in pelvic troubles), I regard it as an instrument of special risk, to be used only after a careful consideration of the danger and the possible benefit to be expected.