Manual of Surgery, Alexis Thomson [new books to read txt] 📗

If the part is aseptic it shrivels, and presents the ordinary features of dry gangrene. It is liable, however, especially in the lower extremity and when the veins also are obstructed, to become infected and to assume the characters of the moist type.

The extent of the gangrene depends upon the site of impaction of the embolus, thus if the abdominal aorta becomes suddenly occluded by an embolus at its bifurcation, the obstruction of the iliacs and femorals induces symmetrical gangrene of both extremities as high as the inguinal ligaments. When gangrene follows occlusion of the external iliac or of the femoral artery above the origin of its deep branch, the death of the limb extends as high as the middle or upper third of the thigh. When the femoral below the origin of its deep branch or the popliteal artery is obstructed, the veins remaining pervious, the anastomosis through the profunda is sufficient to maintain the vascular supply, and gangrene does not necessarily follow. The rupture of a popliteal aneurysm, however, by compressing the vein and the articular branches, usually determines gangrene. When an embolus becomes impacted at the bifurcation of the popliteal, if gangrene ensues it usually spreads well up the leg.

When the axillary artery is the seat of embolic impaction, and gangrene ensues, the process usually reaches the middle of the upper arm. Gangrene following the blocking of the brachial at its bifurcation usually extends as far as the junction of the lower and middle thirds of the forearm.

Gangrene due to thrombosis or embolism is sometimes met with in patients recovering from typhus, typhoid, or other fevers, such as that associated with child-bed. It occurs in peripheral parts, such as the toes, fingers, nose, or ears.

Treatment.—The general treatment of embolic gangrene is the same as that for the senile form. Success has followed opening the artery and removing the embolus. The artery is exposed at the seat of impaction and, having been clamped above and below, a longitudinal opening is made and the clot carefully extracted with the aid of forceps; it is sometimes unexpectedly long (one recorded from the femoral artery measured nearly 34 inches); the wound in the artery is then sewn up with fine silk soaked in paraffin. When amputation is indicated, it must be performed sufficiently high to ensure a free vascular supply to the flaps.

Gangrene following Ligation of Arteries.—After the ligation of an artery in its continuity—for example, in the treatment of aneurysm—the limb may for some days remain in a condition verging on gangrene, the distal parts being cold, devoid of sensation, and powerless. As the collateral circulation is established, the vitality of the tissues is gradually restored and these symptoms pass off. In some cases, however,—and especially in the lower extremity—gangrene ensues and presents the same characters as those resulting from embolism. It tends to be of the dry type. The occlusion of the vein as well as the artery is not found to increase the risk of gangrene.

Gangrene from Mechanical Constriction of the Vessels of the part.—The application of a bandage or plaster-of-Paris case too tightly, or of a tourniquet for too long a time, has been known to lead to death of the part beyond; but such cases are rare, as are also those due to the pressure of a fractured bone or of a tumour on a large artery or vein. When gangrene occurs from such causes, it tends to be of the moist type.

Much commoner is it to meet with localised areas of necrosis due to the excessive pressure of splints over bony prominences, such as the lateral malleolus, the medial condyle of the humerus, or femur, or over the dorsum of the foot. This is especially liable to occur when the nutrition of the skin is depressed by any interference with its nerve-supply, such as follows injuries to the spine or peripheral nerves, disease of the brain, or acute anterior poliomyelitis. When the splint is removed the skin pressed upon is found to be of a pale yellow or grey colour, and is surrounded by a ring of hyperæmia. If protected from infection, the clinical course is that of dry gangrene.

Bed-sores, which are closely allied to pressure sores, will be described at the end of this chapter.

When a localised portion of tissue, for example, a piece of skin, is so severely crushed or bruised that its blood vessels are occluded and its structure destroyed, it dies, and, if not infected with bacteria, dries up, and the shrivelled brown skin is slowly separated by the growth of granulation tissue beneath and around it.

Fingers, toes, or even considerable portions of limbs may in the same way be suddenly destroyed by severe trauma, and undergo mummification. If organisms gain access, typical moist gangrene may ensue, or changes similar to those of ordinary post-mortem decomposition may take place.

Treatment.—The first indication is to exclude bacteria by purifying the damaged part and its surroundings, and applying dry, non-irritating dressings.

When these measures are successful, dry gangrene ensues. The raw surface left after the separation of the dead skin may be allowed to heal by granulation, or may be covered by skin-grafts. In the case of a finger or a limb it is not necessary to wait until spontaneous separation takes place, as this is often a slow process. When a well-marked line of demarcation has formed, amputation may be performed just sufficiently far above it to enable suitable flaps to be made.

The end of a stump, after spontaneous separation of the gangrenous portion, requires to be trimmed, sufficient bone being removed to permit of the soft parts coming together.

If moist gangrene supervenes, amputation must be performed without delay, and at a higher level.

Gangrene from Heat, Chemical Agents, and Cold.—Severe burns and scalds may be followed by necrosis of tissue. So long as the parts are kept absolutely dry—as, for example, by the picric acid method of treatment—the grossly damaged portions of tissue undergo dry gangrene; but when wet or oily dressings are applied and organisms gain access, moist gangrene follows.

Strong chemical agents, such as caustic potash, nitric or sulphuric acid, may also induce local tissue necrosis, the general appearances of the lesions produced being like those of severe burns. The resulting sloughs are slow to separate, and leave deep punched-out cavities which are long of healing.

Carbolic Gangrene.—Carbolic acid, even in comparatively weak solution, is liable to induce dry gangrene when applied as a fomentation to a finger, especially in women and children. Thrombosis occurs in the blood vessels of the part, which at first is pale and soft, but later becomes dark and leathery. On account of the anæsthetic action of carbolic acid, the onset of the process is painless, and the patient does not realise his danger. A line of demarcation soon forms, but the dead part separates very slowly.

Gangrene from Frost-bite.—It is difficult to draw the line between the third degree of chilblain and the milder forms of true frost-bite; the difference is merely one of degree. Frost-bite affects chiefly the toes and fingers—especially the great toe and the little finger—the ears, and the nose. In this country it is seldom seen except in members of the tramp class, who, in addition to being exposed to cold by sleeping in the open air, are ill-fed and generally debilitated. The condition usually manifests itself after the parts, having been subjected to extreme cold, are brought into warm surroundings. The first symptom is numbness in the part, followed by a sense of weight, tingling, and finally by complete loss of sensation. The part attacked becomes white and bleached-looking, feels icy cold, and is insensitive to touch. Either immediately, or, it may be, not for several days, it becomes discoloured and swollen, and finally contracts and shrivels. Above the dead area the limb may be the seat of excruciating pain. The dead portion is cast off, as in other forms of dry gangrene, by the formation of a line of demarcation.

To prevent the occurrence of gangrene from frost-bite it is necessary to avoid the sudden application of heat. The patient should be placed in a cold room, and the part rubbed with snow, or put in a cold bath, and have light friction applied to it. As the circulation is restored the general surroundings and the local applications are gradually made warmer. Elevation of the part, wrapping it in cotton wool, and removal to a warmer room, are then permissible, and stimulants and warm drinks may be given with caution. When by these means the occurrence of gangrene is averted, recovery ensues, its onset being indicated by the white parts assuming a livid red hue and becoming the seat of an acute burning sensation.

A condition known as Trench feet was widely prevalent amongst the troops in France during the European War. Although allied to frost-bite, cold appears to play a less important part in its causation than humidity and constriction of the limbs producing ischæmia of the feet. Changes were found in the endothelium of the blood vessels, the axis cylinders of nerves, and the muscles. The condition does not occur in civil life.

Diabetic Gangrene.—This form of gangrene is prone to occur in persons over fifty years of age who suffer from glycosuria. The arteries are often markedly diseased. In some cases the existence of the glycosuria is unsuspected before the onset of the gangrene, and it is only on examining the urine that the cause of the condition is discovered. The gangrenous process seldom begins as suddenly as that associated with embolism, and, like senile gangrene, which it may closely simulate in its early stages, it not infrequently begins after a slight injury to one of the toes. It but rarely, however, assumes the dry, shrivelling type, as a rule being attended with swelling, œdema, and dusky redness of the foot, and severe pain. According to Paget, the dead part remains warm longer than in other forms of senile gangrene; there is a greater tendency for patches of skin at some distance from the primary seat of disease to become gangrenous, and for the death of tissue to extend upwards in the subcutaneous planes, leaving the overlying skin unaffected. The low vitality of the tissues favours the growth of bacteria, and if these gain access, the gangrene assumes the characters of the moist type and spreads rapidly.

The rules for amputation are the same as those governing the treatment of senile gangrene, the level at which the limb is removed depending upon whether the gangrene is of the dry or moist type. The general treatment for diabetes must, of course, be employed whether amputation is performed or not. Paget recommended that the dietetic treatment should not be so rigid as in uncomplicated diabetes, and that opium should be given freely.

The prognosis even after amputation is unfavourable. In many cases the patient dies with symptoms of diabetic coma within a few days of the operation; or, if he survives this, he may eventually succumb to diabetes. In others there is sloughing of the flaps and death results from toxæmia. Occasionally the other limb becomes gangrenous. On the other hand, the glycosuria may diminish or may even disappear after amputation.

Gangrene associated with Spasm of Blood Vessels.—Raynaud's Disease, or symmetrical gangrene, is supposed to be due to spasm of the arterioles, resulting from peripheral neuritis. It occurs oftenest in women, between the ages of eighteen and thirty, who are the subjects of uterine disorders, anæmia, or chlorosis. Cold is an aggravating factor, as the disease is commonest during the winter months. The digits of both hands or the toes of both feet are simultaneously attacked, and the disease seldom spreads beyond the phalanges or deeper than the skin.

The first evidence is that the fingers become cold, white, and insensitive to touch and pain. These attacks of local syncope recur at varying intervals for months or even years.