The occlusion of the blood-vessels in this diseased condition is a subject which has given rise to much discussion. Some of the earlier writers supposed this phenomenon constituted the disease pyæmia, while others believed it to be the essential cause. Roser says: "But the thrombus is, as can be easily proved, not the cause, but only a symptom, of pyæmia. If a surgical patient—e.g. one suffering with an injury of the head—is attacked by inflammation, and occlusion of a large vein, as of the common iliac vein, for instance, then there are three different theories for the inflammation of the occluded vessel—viz. Hunter's, Rokitansky's, and Virchow's. According to the old Hunterian phlebitic theory, the coagulation of the blood should be the result of the inflammation of the vein. On account of the circumstances under which the coagulation of the blood in the vein has occurred, one might suppose that the cause must be the oozing of coagulable exudation from the inflamed wall of the vein, but pathological dissections, especially Rokitansky's, would not accord with it. Large veins were found plugged up without the existence of corresponding indications of inflammation, and perfectly clear indications were often present that occlusion had preceded the inflammation. Consequently, the occlusion of the vein was the primary condition, and this must be explained in some other way than by its inflammation. Rokitansky in his theory recognized an independent disease of the blood. Yet it does not appear, on examination of the morbid conditions, that this theory can account for them. If it is recognized as correct that a primary disease of the blood is to be admitted, yet the coagulation of the blood in a large vein has not been traced back to it. It remained wholly unexplained why a single vein, especially one so large and strong as the common iliac, should become the seat of the local coagulation. The necessity of finding a local basis for the local coagulation could not be denied. For that reason it was greeted as a highly desirable advance when Virchow pointed out that the occlusion of such large veins could be dependent on the coagulation of the blood in the concave spaces behind the valves of the veins, or through the coagulation in the small branches—e.g. the hypogastric veins, which is gradually carried forward until it reaches the common iliac, and by continual increase this vein may also be filled up. At the same time, it was demonstrated that not infrequently, much oftener than was formerly supposed, the coagulated masses of blood are broken up and carried farther on in the circulation, in this manner producing occlusion of the pulmonary artery or its branches."26
26 Archiv der Heilkunde, Erst. Jahrg., Erst. Heft, S. 4.
The examination of this subject finally brings Roser to this conclusion: "Contamination of the blood is essentially the primary cause of pyæmia; thrombosis is only a result of this morbid contamination, and cannot, therefore, be regarded as the cause of pyæmia, but only as an apparent part, as one of the symptoms of the same."27 The opinion here expressed by Roser I believe to be the one generally entertained by the profession at this time.
27 Ibid., S. 43.
In cases of pyæmia there are recognized two principal sources of contamination of the blood—viz. the wound itself, and the vitiated condition of the atmosphere surrounding the patient—contamination, in the first place, directly from the wound through the blood-vessels; and in the second, by the passage of disease-germs or of the poisonous elements into the blood along the respiratory tract. E. Wagner says: "The latest examinations in regard to the vegetable parasites have made it very probable not only that these are the active agents, but also—what has been clinically quite generally accepted—that septicæmia and pyæmia owe their origin to different plants (the first to rod bacteria, the latter to globular bacteria); and, finally, that both may combine."28 These germs may be generated in the wound or be received into it from the surrounding atmosphere. The character of the wound and the conditions surrounding the patient thus become important subjects for the consideration of the surgeon.
28 Manual of General Pathology, p. 593.
It has been observed, and is now generally admitted, that wounds complicated with a fracture of the long bones of the extremities, opening large medullary cavities and accompanied by extensive laceration of the soft parts, always increase the danger of blood-poisoning. This fact may be more thoroughly understood by a brief consideration of the condition of the parts. Frequently in open fractures large quantities of pus constantly remain in contact with the surface of the wound, while detached fragments of bone, which become speedily necrosed, move about with every motion of the injured limb, lacerating more or less the surrounding tissues, and thus exciting inflammation and suppuration. The periosteum becomes inflamed; a widespread suppurative periostitis is the result; necrosis of the bone from insufficient nutrition follows, while mechanical pressure on the pus aids in its absorption. The medulla frequently takes on suppurative inflammation, and here the surgeon fails to receive prompt warning of danger; slowly the suppuration progresses, without pain or other symptoms unless the disease has extended to the other tissues; the medullary cavity at the fractured end of the bone may be completely or partially occluded by a new osseous formation; and in such cases the absorption of pus by the comparatively large venous vessels of this cavity is greatly facilitated.
The soft parts may also be the seat of dangerous trouble. The same force that produced the wound and fracture may have also contused the soft parts, destroying in a greater or less degree their nutrition, thus giving rise to gangrenous sloughs, or in other cases to the formation of abscesses, etc. I will also call attention to the fact that the laudable pus in these cases is most favorably situated for a rapid change into that commonly called ichorous. The heat of the parts and the contact of the pus with the atmosphere will not fail to effect its rapid decomposition.
ETIOLOGY OF SPONTANEOUS PYÆMIA.—It is unquestionable that cases of true pyæmia have been observed in which the etiology was not traceable to a wound; and it is equally certain that this failure to discover such a source of contamination in the majority of cases is no proof that it did not exist. When it is remembered that a large portion of the alimentary canal, the respiratory and the genito-urinary tracts, are so situated that the existence of a contaminating wound might be absolutely undiscoverable, we are compelled to admit the possibility of a local centre of contamination in all these cases. But the question may be asked here with propriety, "Is fatal pyæmia, independent of a wound, ever produced by breathing vitiated air?" The answers to this question must generally be a negative, although it is certainly true that poisoning of the blood does take place to a certain degree, as is abundantly shown by the different symptoms arising in patients thus exposed who are not suffering with wounds. It is said that dogs exposed in this way are found to rapidly emaciate and suffer from severe and constant diarrhoea. The various symptoms arising in patients confined in overcrowded and pus-infected wards, among which may be mentioned loss of appetite, with diarrhoea and emaciation, are too well known to require an enumeration here. Therefore it appears highly probable that living in and breathing a vitiated atmosphere may act as a strongly predisposing cause, only requiring a slight scratch or abrasion of the skin, in which the infection may be said to act as an exciting cause of pyæmia.
In reference to such complications the following questions are asked by Roser: "Is it a specific deleterious material, a miasmatic or contagious disease-poison, or, as it is generally expressed, a zymotic agent? Must we regard each particular typhus-like fever, with its remarkable changes of blood, with its various localizations in all the organs and membranes, with its chills, furred tongue, petechiæ, delirium, etc., as we regard typhus, scarlatina, variola, etc.? or, as Virchow teaches us, is this pyæmia, so greatly feared by all surgeons, only an ontological idea? Is the word pyæmia only a general name for three different conditions—viz. leucocythæmia, thrombosis, and embolism, or ichorrhæmia and septicæmia? or are there, as many have supposed, two ways in which pyæmia may originate? Is there one primary miasmatic pyæmia analogous to the other epidemic, so-called zymotic diseases? and again, a secondary pyæmia arising from suppurative inflammation, wherein the poison is formed in the patient's own body, which is infected by a single organ?"29