Manual of Surgery, Alexis Thomson [new books to read txt] 📗
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To prevent bleeding in hæmophilics, intra-venous or subcutaneous injections of fresh blood serum, taken from the human subject, the sheep, the dog, or the horse, have proved useful. If fresh serum is not available, anti-diphtheritic or anti-tetanic serum or trade preparations, such as hemoplastin, may be employed. We have removed the appendix and amputated through the thigh in hæmophilic subjects without excessive loss of blood after a course of fresh sheep's serum given by the mouth over a period of several weeks.
The chloride and lactate of calcium, and extract of thymus gland have been employed to increase the coagulability of the blood. The patient should drink large quantities of milk, which also increases the coagulability of the blood. Monro has observed remarkable results from the hypodermic injection of emetin hydrochloride in ½-grain doses.
Thrombosis and EmbolismThe processes known as thrombosis and embolism are so intimately associated with the diseases of blood vessels that it is convenient to define these terms in the first instance.
Thrombosis.—The term thrombus is applied to a clot of blood formed in the interior of the heart or of a blood vessel, and the process by which such a clot forms is known as thrombosis. It would appear that slowing or stagnation of the blood-stream, and interference with the integrity of the lining membrane of the vessel wall, are the most important factors determining the formation of the clot. Alterations in the blood itself, such as occur, for example, in certain toxæmias, also favour coagulation. When the thrombus is formed slowly, it consists of white blood cells with a small proportion of fibrin, and, being deposited in successive layers, has a distinctly laminated appearance on section. It is known as a white thrombus or laminated clot, and is often met with in the sac of an aneurysm (Fig. 72). When rapidly formed in a vessel in which the blood is almost stagnant—as, for example, in a pouched varicose vein—the blood coagulates en masse, and the clot consists of all the elements of the blood, constituting a red thrombus (Fig. 66). Sometimes the thrombus is mixed—a red thrombus being deposited on a white one, it may be in alternate layers.
When aseptic, a thrombus may become detached and be carried off in the blood-stream as an embolus; it may become organised; or it may degenerate and undergo calcification. Occasionally a small thrombus situated behind a valve in a varicose vein or in the terminal end of a dilated vein—for example in a pile—undergoes calcification, and is then spoken of as a phlebolith; it gives a shadow with the X-rays.
When infected with pyogenic bacteria, the thrombus becomes converted into pus and a localised abscess forms; or portions of the thrombus may be carried as emboli in the circulation to distant parts, where they give rise to secondary foci of suppuration—pyæmic abscesses.
Embolism.—The term embolus is applied to any body carried along in the circulation and ultimately becoming impacted in a blood vessel. This occurrence is known as embolism. The commonest forms of embolus are portions of thrombi or of fibrinous formations on the valves of the heart, the latter being usually infected with micro-organisms.
Embolism plays an important part in determining one form of gangrene, as has already been described. Infective emboli are the direct cause of the secondary abscesses that occur in pyæmia; and they are sometimes responsible for the formation of aneurysm.
Portions of malignant tumours also may form emboli, and their impaction in the vessels may lead to the development of secondary growths in distant parts of the body.
Fat and air embolism have already been referred to.
ArteritisPyogenic.—Non-suppurative inflammation of the coats of an artery may so soften the wall of the vessel as to lead to aneurysmal dilatation. It is not uncommon in children, and explains the occurrence of aneurysm in young subjects.
When suppuration occurs, the vessel wall becomes disintegrated and gives way, leading to secondary hæmorrhage. If the vessel ruptures into an abscess cavity, dangerous bleeding may occur when the abscess bursts or is opened.
Syphilitic.—The inflammation associated with syphilis results in thickening of the tunica intima, whereby the lumen of the vessel becomes narrowed, or even obliterated—endarteritis obliterans. The middle coat usually escapes, but the tunica externa is generally thickened. These changes cause serious interference with the nutrition of the parts supplied by the affected arteries. In large trunks, by diminishing the elasticity of the vessel wall, they are liable to lead to the formation of aneurysm.
Changes in the arterial walls closely resembling those of syphilitic arteritis are sometimes met with in tuberculous lesions.
Arterio-sclerosis or Chronic Arteritis.—These terms are applied to certain changes which result in narrowing of the lumen and loss of elasticity in the arteries. The condition may affect the whole vascular system or may be confined to particular areas. In the smaller arteries there is more or less uniform thickening of the tunica intima from proliferation of the endothelium and increase in the connective tissue in the elastic lamina—a form of obliterative endarteritis. The narrowing of the vessels may be sufficient to determine gangrene in the extremities. In course of time, particularly in the larger arteries, this new tissue undergoes degeneration, at first of a fatty nature, but progressing in the direction of calcification, and this is followed by the deposit of lime salts in the young connective tissue and the formation of calcareous plates or rings over a considerable area of the vessel wall. To this stage in the process the term atheroma is applied. The endothelium over these plates often disappears, leaving them exposed to the blood-stream.
Changes of a similar kind sometimes occur in the middle coat, the lime salts being deposited among the muscle fibres in concentric rings.
Fig. 65.—Radiogram showing Calcareous Degeneration (Atheroma) of Arteries.
The primary cause of arterio-sclerosis is not definitely known, but its almost constant occurrence, to a greater or less degree, in the aged suggests that it is of the nature of a senile degeneration. It is favoured by anything which throws excessive strain on the vessel walls, such as heavy muscular work; by chronic alcoholism and syphilis; or by such general diseases as tend to raise the blood-pressure—for example, chronic Bright's disease or gout. It occurs with greater frequency and with greater severity in men than in women.
Atheromatous degeneration is most common in the large arterial trunks, and the changes are most marked at the arch of the aorta, opposite the flexures of joints, at the mouths of large branches, and at parts where the vessel lies in contact with bone. The presence of diseased patches in the wall of an artery diminishes its elasticity and favours aneurysmal dilatation. Such a vessel also is liable to be ruptured by external violence and so give rise to traumatic aneurysm. Thrombosis is liable to occur when calcareous plates are exposed in the lumen of the vessel by destruction of the endothelium, and this predisposes to embolism. Arterio-sclerosis also interferes with the natural arrest of hæmorrhage, and by rendering the vessels brittle, makes it difficult to secure them by ligature. In advanced cases the accessible arteries—such as the radial, the temporal or the femoral—may be felt as firm, tortuous cords, which are sometimes so hard that they have been aptly compared to “pipe-stems.” The pulse is smaller and less compressible than normal, and the vessel moves bodily with each pulsation. It must be borne in mind, however, that the condition of the radial artery may fail to afford a clue to that of the larger arteries. Calcified arteries are readily identified in skiagrams (Fig. 65).
We have met with a chronic form of arterial degeneration in elderly women, affecting especially the great vessels at the root of the neck, in which the artery is remarkably attenuated and dilated, and so friable that the wall readily tears when seized with an artery-forceps, rendering ligation of the vessel in the ordinary way well-nigh impossible. Matas suggests infolding the wall of the vessel with interrupted sutures that do not pierce the intima, and wrapping it round with a strip of peritoneum or omentum.
The most serious form of arterial thrombosis is that met with in the abdominal aorta, which is attended with violent pains in the lower limbs, rapidly followed by paralysis and arrest of the circulation.
Thrombo-Phlebitis and Thrombosis in VeinsThrombosis is more common in veins than in arteries, because slowing of the blood-stream and irritation of the endothelium of the vessel wall are, owing to the conditions of the venous circulation, more readily induced in veins.
Venous thrombosis may occur from purely mechanical causes—as, for example, when the wall of a vein is incised, or the vessel included in a ligature, or when it is bruised or crushed by a fragment of a broken bone or by a bandage too tightly applied. Under these conditions thrombosis is essentially a reparative process, and has already been considered in relation to the repair of blood vessels.
In other cases thrombosis is associated with certain constitutional diseases—gout, for example; the endothelium of the veins undergoing changes—possibly the result of irritation by abnormal constituents in the blood—which favour the formation of thrombi.
Under these various conditions the formation of a thrombus is not necessarily associated with the action of bacteria, although in any of them this additional factor may be present.
The most common cause of venous thrombosis, however, is inflammation of the wall of the vein—phlebitis.
Phlebitis.—Various forms of phlebitis are met with, but for practical purposes they may be divided into two groups—one in which there is a tendency to the formation of a thrombus; the other in which the infective element predominates.
In surgical patients, the thrombotic form is almost invariably met with in the lower extremity, and usually occurs in those who are debilitated and anæmic, and who are confined to bed for prolonged periods—for example, during the treatment of fractures of the leg or pelvis, or after such operations as herniotomy, prostatectomy, or appendectomy.
Clinical Features.—The most typical example of this form of phlebitis is that so frequently met with in the great saphena vein, especially when it is varicose. The onset of the attack is indicated by a sudden pain in the lower limb—sometimes below, sometimes above the knee. This initial pain may be associated with shivering or even with a rigor, and the temperature usually rises one or two degrees. There is swelling and tenderness along the line of the affected vein, and the skin over it is a dull-red or purple colour. The swollen vein may be felt as a firm cord, with bead-like enlargements in the position of the valves. The patient experiences a feeling of stiffness and tightness throughout the limb. There is often œdema of the leg and foot, especially when the limb is in the dependent position. The acute symptoms pass off in a few days, but the swelling and tenderness of the vein and the œdema of the limb may last for many weeks.
When the deep veins—iliac, femoral, popliteal—are involved, there is great swelling of the whole limb, which is of a firm almost “wooden” consistence, and of a pale-white colour; the œdema may be so great that it is impossible to feel the affected vein until the swelling has subsided. This is most often seen in puerperal women, and is known as phlegmasia alba dolens.
Treatment.—The patient must be placed at absolute rest, with the foot of the bed raised on blocks 10 or 12 inches high, and the limb immobilised by sand-bags or splints. It is necessary to avoid handling the parts, lest
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