HEMOGLOBIN.
The principal interest of the red blood corpuscles for the surgeon, aside from their relative number and shape, inheres in their relation to hemoglobin, and hemoglobin is of particular interest here because much can be learned by estimating the proportion in which it is present. Hemoglobin has, furthermore, an interest which reaches beyond the mere blood appearance, since it is considered to be the apparent source from which both the urinary and biliary pigments are produced. That the amount contained in the blood varies within wide limits under different conditions has long been known. When notably reduced in amount the condition is referred to as oligochromemia. The ideal normal standard is present in but a small proportion of cases, even in strong young men in the third decade of life. The average is considerably lower and can scarcely be placed above 90 per cent. Females show a smaller amount than males—3 or 4 per cent. less. In anemia its reduction is not usually proportionate to that in the number of red cells. After hemoglobin loss, as after surgical operations, much can be gained in the matter of prognosis by estimating the speed of its regeneration. With regard to how much actual hemoglobin loss a patient can bear, it seems to be more important to determine how much still remains in the body. The minimum is apparently 20 per cent. In three cases dying of collapse after operation, Mikulicz found only 15 per cent. remaining. The rapidity of regeneration is a fairly accurate indication of improvement in every other respect. Regeneration is interfered with by constitutional syphilis, and, on the other hand, is often apparently favored in cases of tuberculosis. In malignant tumors the average of hemoglobin is reduced to about 60 per cent., and in these cases also complete regeneration is materially retarded. Incomplete removal or recurrence of cancer prevents typical regeneration or restoration, while, after successful or radical removal, complete restoration to the previous standard, often with positive gain, is obtained. Thus, a woman who had gained thirty pounds after resection of a cancerous pylorus, showed, after three months, hemoglobin repair to the amount of 65 per cent. A prognostic significance often attaches to the accurate estimation of hemoglobin at intervals after removal of malignant tumors.
A very convenient method for the ready estimation of hemoglobin is afforded by the Tallquist color scale. It can be practised at the bedside and is sufficiently accurate for the surgeon’s general purposes.
THROMBOSIS.
Thrombosis is a term applied to the formation of a thrombus—i. e., a clot within the cavity of the heart or one of the bloodvessels—the term being limited to coagulation of blood within these natural cavities, and without specifying the exciting cause of the same. A clot so formed is called a thrombus. To be accurate, a distinction should be made between a thrombus, which is caused always before death—or, rather, during life—and the clot, which is essentially a postmortem affair. Our application, then, of the terms “thrombosis” and “thrombus” refers solely to that which takes place during life. In order to appreciate the conditions which lead to thrombosis it is necessary to fully appreciate the reciprocal conditions which must normally be maintained between the circulating blood and the walls of the vessels in which it flows. Fluidity of blood depends always upon integrity of the vessel wall. As long as its lining membrane is absolutely undisturbed and normal, moving blood will never coagulate within it, and the only thrombi that may be met within it are those which are propagated from a distance. Coagulation of blood is, for the main part, associated with the peculiar properties of fibrin.
Fibrin is produced from fibrinogen, a globulin which is held in solution under ordinary circumstances, which has certain peculiarities of its own. When the change occurs it is entirely consumed and none remains in the blood serum. Fibrinogen is split up by a peculiar ferment called thrombin into what we ordinarily speak of as fibrin and a small amount of a soluble globulin, which remains in solution in the serum. Thrombin is not a normal constituent of the blood, but is formed when it escapes, as the result of the reaction between certain calcium salts and a nucleoproteid, which has been called prothrombin. The latter arises from the disintegration of the leukocytes, especially the polynuclear, and the blood plaques, after the blood leaves the bloodvessels. Calcium salts seem absolutely necessary for coagulation; hence the value of the administration of calcium chloride in certain cases previous to operation. Another essential feature seems to be the absolute integrity of the endothelial lining of the bloodvessels, although for this fact there is no satisfactory explanation. If a portion of a vein is removed from the body after double ligation its contained blood will not coagulate for a long time. Blood which is kept circulating through the lungs and heart alone soon loses its coagulability; hence the liver seems to be concerned in some way in maintaining it. Certain other substances also seem to retard coagulation, such as the albumoses of snake venom, and certain synthetic, colloid, proteid-like substances, which can be introduced very gradually. If, however, they are introduced rapidly, or in large quantities, thrombosis occurs promptly. We have much to learn about the coagulation of the blood, but the above facts are at least suggestive to the surgeon.
PLATE II
FIG. 1
Small Vein showing Diapedesis of Leukocytes. (Engelmann.)