Chapter V

.)

=Fat Embolism.=--Fat embolism as a distinct, sometimes fatal, surgical condition has received of late so much study as to be entitled to consideration by itself. By this term is meant a plugging of small arteries by minute drops of fat, which, having been set free somewhere about the periphery, are carried into the venous circulation and thence distributed to various parts of the system. Inasmuch as the capillaries of the lungs are often their first lodging place, fat embolism here is most often met with, and consequently recognized and studied. But it may occur in the brain, the choroid, the kidneys, or other parts, provided only that there has been sufficient _ris a tergo_ on the part of the heart to force the fat globules through the pulmonary capillaries and into the systemic circulation.

[Illustration: FIG. 2

Fat embolism of lungs. Large branching pulmonary artery filled with spherical, oval, cylindrical, and branching masses of fat. Fresh mashed preparation in potassium hydrate. (Kaiserling.)]

Fat embolism occurs frequently, and to a slight extent in nearly every case of fracture and laceration. So common is it, and so closely allied are some of its most prominent symptoms to those of shock, that as a matter of fact many cases heretofore considered shock are to be regarded as instances of this condition. Indeed, even in a miscellaneous series of 260 dead bodies fat embolism was found in 10 per cent. The injuries most likely to be followed by it are simple, and particularly compound fractures of bones; laceration of soft parts, especially of adipose tissues; certain surgical operations; acute infections of bone and periosteum; rupture of fatty liver; and certain pathological conditions where the phenomena are not so easily explained, _e. g._, icterus gravis, diabetes, etc.

Drops of fat may be seen floating on fluid or semifluid blood after many operations and compound injuries, and the possibility of escape of fat--or, more accurately, its suction into the vessels from which this blood has escaped--is easily appreciable. But it has also been shown that absorption of fat is possible even from serous surfaces, and that fat embolism may occur when fluid fat has been passed into the heart through the thoracic duct, although more slowly. Oil drops are also found in the interior of the tissues, while in a piece of lung spread out in water in the visible vessels highly refracting fatty material may be noted. _Fatty infarction_, particularly in the lower lobes, is sometimes plainly visible to the naked eye. Under a low objective, especially with osmic-acid staining, the presence of fat is easily demonstrated.

The essential danger in case of fat embolism is of so clogging the pulmonary capillaries that oxygenation shall become so imperfect as to lead to absolute asphyxiation from carbonic dioxide poisoning. When this fact is understood, the cyanosis, the rapid breathing, the overaction of the heart, etc., are easily and correctly interpreted.

Fat embolism by itself cannot cause inflammation nor infection, nor sepsis in any sense. It may, however, lead to ecchymoses in conjunction with fatty infarcts in the organs most affected. The minute hemorrhages are easily explained by the bursting of the capillaries in the attempt to force blood through them. Fatty emboli, however, take the same course as do septic--are carried first to the right side of the heart and distributed over the lungs; are, if the patient lives, forced through the lungs into the systemic circulation, and are then carried to the brain, kidneys, etc. The first symptoms are referable to the plugging of the pulmonary capillaries; the secondary symptoms to the systemic disturbance.

=Symptoms.=--Pallor of countenance with facial expression of anxiety and distress, followed by cyanosis and contracted pupils, are seen. Patients are usually first excited, sometimes more or less disturbed, then become somnolent, and, finally, comatose in the fatal cases. The respiration rate increases from normal up to 50 or 60, and breathing is sometimes stertorous. Dyspnea, increasing in intensity until it becomes agonizing, sometimes marks these cases. Occasionally foam, possibly blood, proceeds from the mouth, as in edema of the lungs. Sometimes hemoptysis occurs. The pulse becomes weak, frequent, and irregular, while toward the close it is fluttering. Temperature is not notably disturbed, at least not typically.

These symptoms set in usually within thirty-six to seventy-two hours after the lesion which has caused them. I have, however, known death to occur in one or more cases within eighteen hours after reception of injury.

After fat has been forced through the lungs and carried to the kidneys it will be eliminated with the urine, and may be found floating upon it in the shape of oil-like drops. Discovery of this condition is positive evidence of fat embolism. It is to be distinguished from shock in that by the time the symptoms of embolic disturbance are at their height, all or nearly all symptoms of pure shock have subsided. Furthermore, cyanosis and embarrassment of respiration are not indicative of shock; and, finally, the discovery of fat in the urine will be corroborative.

A mild degree of fat embolism may be noted, if looked for, after almost all serious fractures. It will give rise to slight embarrassment of respiration and cyanosis and to the elimination of fat by the kidneys.

=Prognosis.=--Prognosis varies according to the extent of the injury and the proximity of the lesion to the heart and lungs; also to the possibility of continuous entrance of fat, _i. e._, from its continual absorption. Prognosis really depends upon whether the heart can be given sufficient vigor and endurance to continue pumping blood with its burden of fat through the pulmonary circulation. A secondary danger may come from the circulation of this fat-ladened blood through the capillaries of the brain. Should the source of motive power thus become paralyzed with resulting general enfeeblement, death may ensue. When well-marked evidences of fat embolism are present, but are followed by recovery, the worst of the trouble is usually over within forty-eight hours after it begins.

=Treatment.=--Obviously treatment is mainly directed toward the heart, so that we may stimulate it to carry its load of fat through from the venous into the arterial system. If it can do this, the fat is disposed of by oxidation or is saponified by the alkalies in the blood. Physiological rest of the injured part is the first indication, however, and if this occurs in a patient, say with delirium tremens, powerful mechanical restraint may be necessary. The most effective cardiac stimulants are called for--alcohol, adrenalin, strychnine. In other respects treatment is largely symptomatic. Next to giving the heart vigor in this way, inhalations of oxygen give the most promise, because of the crying need of the system during this ordeal for this life-giving gas.[1]

[1] See paper by the author. New York Medical Journal, August 16, 1884.

PHYSICAL PROPERTIES OF THE LEUKOCYTES.

=Phagocytosis.=--All leukocytes have the power of shifting their location. The lymphocytes, so called, being the youngest of the white corpuscles, show it less than the older forms. The eosinophile cells are less able to manifest the peculiar activities of the other forms. It is particularly the mononuclear and polynuclear corpuscles which are endowed with most pronounced activity. These have the power, like the ameba among the lowest forms of life, to not only spread themselves around inert bodies, like granules of carmine or other

## particles used for experiment, or the particles of coal-dust found in

certain conditions in the human body, but they also have the power to englobe many living organisms, for the main part vegetable (bacteria). Under the microscope it is possible to see living bacilli, performing

## active movements, although enclosed in the nutritive vacuoles of

the leukocytes, in some of the lower animals. This _ameboid_ power possessed by these cells of thus attacking and disposing of foreign bodies or irritants has been demonstrated and proved, especially by Metchnikoff, and has been called by him _phagocytosis_. His views were for a long time disputed, and are perhaps not yet absolutely and generally accepted. Nevertheless, they fulfil every demand made upon them for explanation, and are susceptible of such demonstration under the microscope that we now have practically a new and apparently a correct theory of the inflammatory process. (See