The pathological changes in pyæmia simplex are of the same kind as those which have just been described as characterizing pyæmia multiplex, with the exception of the metastatic abscesses, which are always absent. Furthermore, the disease in both instances is believed to have its origin from the same causes, and the dissimilarities in the pathological lesions are equally susceptible of a rational explanation, as are those of scarlatina simplex and scarlatina maligna.
There were reported by the committee of the London Pathological Society some interesting details pertaining to this form of pyæmia. Their report shows that among the one hundred and fifty-five cases classed as pyæmia there were twenty-four cases without visceral abscesses; and furthermore it shows that in twenty-three of these cases there was no suppuration, although local inflammations affected many of the different tissues, since these patients suffered with arthritis, cellulitis, pleuritis, meningitis, pericarditis, and carditis. It is also added that "the post-mortem appearances, in addition to the local secondary inflammation before noted, were in many cases those changes common to all forms of blood poisoning. Out of the twenty-four cases, the following are noted: Swollen spleen, nine times; congestion of the lungs, ten times; swollen liver, six times; cloudy swelling of the kidney, fourteen times."38
38 Trans. London Pathological Soc., vol. xxx. p. 26.
In this form of pyæmia it has been supposed by some authors that the materies morbi occasionally produces death before the metastatic abscesses have had time to develop, but this is not always the case. The same committee report on the above-mentioned twenty-four cases, on this point, as follows: "The duration of the cases before the fatal termination was very various. It is tolerably accurately recorded in eighteen cases: of these five died in the first week, five in the second, four in the third, and the remaining four survived to the thirtieth, forty-ninth, fifty-second, and sixty-second days."39
39 Trans. London Pathological Soc., p. 25 et seq.
The pathology of pyæmia multiplex having been already fully described, and since the only essential difference in these morbid conditions consists in the complete absence of the metastatic abscesses in cases of pyæmia simplex, it is therefore thought unnecessary to dwell here longer on this subject.
The morbid anatomy of septicæmia has been carefully studied of late, and it is now known that the most characteristic lesions are found in the blood and the alimentary canal.
As a manifestation of the general poisoning of the blood, it might be expected that putrefaction would follow rapidly after the death of the patient. In fact, Davine defines septicæmia as "putrefaction of a living body." Observation has now thoroughly confirmed that which was formerly an anticipation. Panum, Hemmer, and Bergmann have each called attention to the fact that rapid decomposition follows the death of all animals in which septicæmia has been produced for experimental purposes. It has also been observed that putrefaction in the human cadaver begins much sooner, and progresses much more rapidly, under similar circumstances, when the death has been produced by this disease than when it has occurred from any other cause. Furthermore, this rapid decomposition is not limited to the internal organs, but may be frequently strongly marked on the surface of the body after the lapse of twelve hours, although it has been kept in a comparatively dry and cool atmosphere. In those cases where the septicæmia has originated in an external wound it has been uniformly observed that putrefaction goes on most rapidly in the vicinity of the wound after the death of the patient.
In every case of fatal septicæmia the post-mortem examination will show that the coagulability of the blood has been diminished or destroyed. In fact, it has been abundantly shown that in all cases of true septicæmia the coagulability of the blood is more or less diminished. The few imperfect clots of blood found after death are of a deep-black color. The putrefaction of the soft tissues is greatly hastened by the presence of this blood; and, consequently, this process goes on most rapidly in the most dependent portions of the body, especially along the course of the large veins. The septicæmic blood possesses a peculiar putrefactive odor, and it is occasionally found to be acid in its reaction, according to Vogel and Scherer, making it highly probable that it will end in the formation of the carbonate of ammonium. The chemical examinations of septicæmic blood which have heretofore been made have completely failed to give satisfactory results in regard either to the existence or nature of the materies morbi in this disease, although, without doubt, there has occasionally been found, principally in the blood of those who have died of acute septic intoxication, a poisonous substance, which Bergmann designated sepsin. Microscopic examinations have shown that in the blood and also in various organs of those who have died of septicæmia there are always present, under these circumstances, a large number of the rod bacteria; in fact, they are more numerous than after death from any other infectious disease. Furthermore, they are found in the blood, lymph-glands, and cellular tissues during the whole course of the disease.
There are no pathological changes in the central nervous system which arise directly from septicæmia, although in some cases, when there has been some cardiac complication or very severe dyspnoea from any cause immediately prior to the death of the patient, there may be found hyperæmia of the membranes of the cerebro-spinal axis. The brain and spinal cord remain unchanged.