64 Quoted by Levrat, p. 78.
The infecting power of cancer is certainly not equal to that of gangrene. Nevertheless, Lancereaux has shown that cancerous nodules may be produced by metastasis. This belief in the possibility of a simple embolus taking on a cancerous change, and carrying this disease to far-removed parts, has been strongly combated by Cohn. Neither experimental nor human pathology has thus far decided the subject in an absolute manner. Certain it is, however, that the power of emboli from cancerous foci to carry similar disease elsewhere depends partly upon the vitality of the cancerous particles, partly upon the power of receptivity as shown by certain constitutions for developing special diseases, and which relates, after all, to the general question of dyscrasia. Langenbeck has shown that certain animals will die within a few hours after the injection of cancerous juice. On the other hand, it is known that the infective power of the juice only lasts a very brief period. Weber, Luzzato, and others have reported numerous examples of secondary tumors of similar nature developed in the lungs when epithelioma, enchondroma, sarcoma, or carcinoma existed somewhere in the body. Finally, it would appear that emboli containing hydatids in embryo have been the means of transporting these parasites into the pulmonary structure.
DIAGNOSIS.—The sudden commencement of the accidents, especially when a peripheral thrombus has existed previously in one of the large veins of the extremities, renders the diagnosis almost certain. If the patient has been suffering from the effects of a traumatism (contusion, fractures, operation on the veins of the limbs or rectum, etc.), and is almost instantaneously attacked with intense dyspnoea and a feeling of anguish which he refers to the thoracic region, we shall be able usually to eliminate other intercurrent affections and to diagnosticate the existence of pulmonary embolism.
This accident is often confounded with cardiac thrombosis. It may usually be separated from it by the following differential symptoms: Cardiac obstruction from a clot usually comes on insidiously, by degrees; the heart-beats are irregular, tumultuous, muffled, and distant; there may be a murmur from one or other of the cardiac orifices; there is no initial chill; peripheral thrombosis is not present as a rule; there is no sensation of localized obstruction in the chest.
In pulmonary embolism the début may be instantaneous and death follow in a few seconds; or, again, the beginning may be rapid, ushered in by stifling in the chest, a chill, cyanosed face, followed soon by excessive pallor, a distinct sensation of obstacle to breathing in a particular region. Percussion and auscultation may remain negative. The patient may have a succession of similar accidents, and yet finally recover. According to Ball, pulmonary embolism and pulmonary thrombosis cannot be distinguished during life. In one case which he reports where pulmonary embolism should have been present without question the autopsy showed the presence of a thrombus in the pulmonary artery. A succession of chills, general malaise, febrile excitement, the localized phenomena of pneumonia or gangrene of the lung, point indubitably to the existence of septic emboli.
The differential diagnosis between pulmonary embolism and other affections, such as angina pectoris, a foreign body in the air-passages, pneumothorax, etc., may usually be reached without much difficulty. Sometimes the paroxysmal dyspnoea with sensations of great oppression which accompanies mitral stenosis may be mistaken for pulmonary embolism. In these instances the absence of a discoverable cause of the attack in pre-existing emboli, and the presystolic murmur with marked general anæmia, may surely lead to an accurate diagnosis. It must, however, always be remembered that in mitral stenosis it is not infrequent to have cardiac coagula formed in the right auricle, which may become detached and give rise to pulmonary emboli. Under these circumstances a severe localized pain in the side of the chest has considerable diagnostic importance as pointing to the presence of a pulmonary embolus (Cohn).
When there is pre-existing cardiac disease of organic nature a syncopal attack may sometimes occasion doubt with respect of a correct diagnosis. The sudden loss of consciousness, excessive pallor, and absence of pulse will ordinarily, however, confirm the diagnosis of syncope. Rupture of the heart is accompanied with symptoms of syncope rather than those of suffocation (Balzer). Emboli of the bronchial arteries are not accompanied by any characteristic symptoms which will enable us to make a differential diagnosis. There is the same sudden dyspnoea, the initial chill and hæmoptysis, as in pulmonary embolism (Penzold).
PROGNOSIS.—As will be readily understood, the prognosis is sometimes difficult to estimate and varies with many circumstances. Certain emboli, even among those which have occasioned severe symptoms, have never been recognized. Other pulmonary emboli always remain comparatively latent. In this connection we should mention those which take place in the lungs of tuberculous patients. Again, the size and seat of the embolus will always have great importance in regard to the prognosis. If the trunk or primary divisions of the pulmonary artery be suddenly and completely obstructed by emboli, sudden death will surely follow. If secondary divisions of the pulmonary artery are filled up, more or less grave symptoms will usually follow. When emboli are carried into the tertiary or still smaller branches of the artery, they may not occasion any appreciable phenomena other than a moderate and passing dyspnoea. If, however, there be a large number of small emboli carried into both lungs at the same time, it is possible that rapid death may follow their presence. It is true, however, according to certain authors, that even a large embolus blocking up the main trunk of the pulmonary artery may be followed by recovery. Such a case is that of Jacquemier, reported by Ball. Even in this case, whilst the presence of the embolus cannot perhaps be doubted, still the exact size and location may be called in question. And here we may add that in all cases of reported cure of this nature there will naturally and inevitably exist an atmosphere of legitimate doubt about the correct observations and diagnosis of the narrated facts.
What precedes relates exclusively to the existence of simple emboli. Of course if the embolus be of septic origin, it will be followed by the appearance in the lungs of foci of purulent pneumonia or of gangrenous changes of tissue which will finally produce such structural destruction as almost certainly to terminate in death.
TREATMENT.—The majority of those who have studied this subject have recognized how vain are our efforts of treatment in many instances. Pulmonary embolism is one of those accidents which we should always be prepared to admit, however, when its characteristic symptoms show themselves, and should endeavor rationally to combat by the therapeutic means in our power. Even before we have any signs present which indicate obstruction of the pulmonary circulation, we may have those which point in a very certain manner to the existence of a peripheral thrombus. This thrombus may block up completely one of the large veins of the lower extremities, and may, owing to its possible detachment and transport, be a constant menace to life. At times these peripheral thrombi are accompanied by local inflammatory symptoms which belong to phlebitis. This condition of things is not uncommon after fractures or other traumatisms. Frequently there is no evidence of any inflammatory state, and we recognize the thrombus solely by the signs which result directly from obstructed venous circulation and by the existence of a hard, indurated cord which fills the vein at a given level. Now, what are the means we have at our command to prevent the transport of this coagulum, or indeed to dissolve it, or absorb it in its place?