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CHAPTER VI

GANGRENE


Definition--Types: _Dry_, _Moist_--Varieties--Gangrene primarily due to

   interference with circulation: _Senile gangrene_; _Embolic
   gangrene_; _Gangrene following ligation of arteries_; _Gangrene
   from mechanical causes_; _Gangrene from heat, chemical agents, and
   cold_; _Diabetic gangrene_; _Gangrene associated with spasm of
   blood vessels_; _Raynaud's disease_; _Angio-sclerotic gangrene_;
   _Gangrene from ergot_. Bacterial varieties of gangrene.
   _Pathology_--clinical varieties--_Acute infective gangrene_;
   _Malignant oedema_; _Acute emphysematous_ or _gas gangrene_;
   _Cancrum oris_, _etc_. Bed-sores: _Acute_; _chronic_.

Gangrene or mortification is the process by which a portion of tissue dies _en masse_, as distinguished from the molecular or cellular death which constitutes ulceration. The dead portion is known as a _slough_.

In this chapter we shall confine our attention to the process as it affects the limbs and superficial parts, leaving gangrene of the viscera to be described in regional surgery.


TYPES OF GANGRENE

Two distinct types of gangrene are met with, which, from their most obvious point of difference, are known respectively as _dry_ and _moist_, and there are several clinical varieties of each type.

Speaking generally, it may be said that dry gangrene is essentially due to a simple _interference with the blood supply_ of a part; while the main factor in the production of moist gangrene is _bacterial infection_.

The cardinal signs of gangrene are: change in the colour of the part, coldness, loss of sensation and motor power, and, lastly, loss of pulsation in the arteries.

  1. Dry Gangrene# or #Mummification# is a comparatively slow form of local

death due, as a rule, to a diminution in the arterial blood supply of the affected part, resulting from such causes as the gradual narrowing of the lumen of the arteries by disease of their coats, or the blocking of the main vessel by an embolus.

As the fluids in the tissues are lost by evaporation the part becomes dry and shrivelled, and as the skin is usually intact, infection does not take place, or if it does, the want of moisture renders the part an unsuitable soil, and the organisms do not readily find a footing. Any spread of the process that may take place is chiefly influenced by the anatomical distribution of the blocked arteries, and is arrested as soon as it reaches an area rich in anastomotic vessels. The dead portion is then cast off, the irritation resulting from the contact of the dead with the still living tissue inducing the formation of granulations on the proximal side of the junction, and these by slowly eating into the dead portion produce a furrow--the _line of demarcation_--which gradually deepens until complete separation is effected. As the muscles and bones have a richer blood supply than the integument, the death of skin and subcutaneous tissues extends higher than that of muscles and bone, with the result that the stump left after spontaneous separation is conical, the end of the bone projecting beyond the soft parts.

_Clinical Features._--The part undergoing mortification becomes colder than normal, the temperature falling to that of the surrounding atmosphere. In many instances, but not in all, the onset of the process is accompanied by severe neuralgic pain in the part, probably due to anaemia of the nerves, to neuritis, or to the irritation of the exposed axis cylinders by the dead and dying tissues around them. This pain soon ceases and gives place to a complete loss of sensation. The dead part becomes dry, horny, shrivelled, and semi-transparent--at first of a dark brown, but finally of a black colour, from the dissemination of blood pigment throughout the tissues. There is no putrefaction, and therefore no putrid odour; and the condition being non-infective, there is not necessarily any constitutional disturbance. In itself, therefore, dry gangrene does not involve immediate risk to life; the danger lies in the fact that the breach of surface at the line of demarcation furnishes a possible means of entrance for bacteria, which may lead to infective complications.

  1. Moist Gangrene# is an acute process, the dead part retaining its fluids

and so affording a favourable soil for the development of bacteria. The action of the organisms and their toxins on the adjacent tissues leads to a rapid and wide spread of the process. The skin becomes moist and macerated, and bullae, containing dark-coloured fluid or gases, form under the epidermis. The putrefactive gases evolved cause the skin to become emphysematous and crepitant and produce an offensive odour. The tissues assume a greenish-black colour from the formation in them of a sulphide of iron resulting from decomposition of the blood pigment. Under certain conditions the dead part may undergo changes resembling more closely those of ordinary post-mortem decomposition. Owing to its nature the spread of the gangrene is seldom arrested by the natural protective processes, and it usually continues until the condition proves fatal from the absorption of toxins into the circulation.

The _clinical features_ vary in the different varieties of moist gangrene, but the local results of bacterial action and the constitutional disturbance associated with toxin absorption are present in all; the prognosis therefore is grave in the extreme.

From what has been said, it will be gathered that in dry gangrene there is no urgent call for operation to save the patient's life, the primary indication being to prevent the access of bacteria to the dead part, and especially to the surface exposed at the line of demarcation. In moist gangrene, on the contrary, organisms having already obtained a footing, immediate removal of the dead and dying tissues, as a rule, offers the only hope of saving life.


VARIETIES OF GANGRENE

  1. Varieties of Gangrene essentially due to Interference with the

Circulation#

While the varieties of gangrene included in this group depend primarily on interference with the circulation, it is to be borne in mind that the clinical course of the affection may be profoundly influenced by superadded infection with micro-organisms. Although the bacteria do not play the most important part in producing tissue necrosis, their subsequent introduction is an accident of such importance that it may change the whole aspect of affairs and convert a dry form of gangrene into one of the moist type. Moreover, the low state of vitality of the tissues, and the extreme difficulty of securing and maintaining asepsis, make it a sequel of great frequency.

  1. Senile Gangrene.#--Senile gangrene is the commonest example of local

death produced by a _gradual_ diminution in the quantity of blood passing through the parts, as a result of arterio-sclerosis or other chronic disease of the arteries leading to diminution of their calibre. It is the most characteristic example of the dry type of gangrene. As the term indicates, it occurs in old persons, but the patient's age is to be reckoned by the condition of his arteries rather than by the number of his years. Thus the vessels of a comparatively young man who has suffered from syphilis and been addicted to alcohol are more liable to atheromatous degeneration leading to this form of gangrene than are those of a much older man who has lived a regular and abstemious life. This form of gangrene is much more common in men than in women. While it usually attacks only one foot, it is not uncommon for the other foot to be affected after an interval, and in some cases it is bilateral from the outset. It must clearly be understood that any form of gangrene may occur in old persons, the term senile being here restricted to that variety which results from arterio-sclerosis.

[Illustration: FIG. 20.--Senile Gangrene of the Foot, showing line of demarcation.]

_Clinical Features._--The commonest seat of the disease is in the toes, especially the great toe, whence it spreads up the foot to the heel, or even to the leg (Fig. 20). There is often a history of some slight injury preceding its onset. The vitality of the tissues is so low that the balance between life and death may be turned by the most trivial injury, such as a cut while paring a toe-nail or a corn, a blister caused by an ill-fitting shoe or the contact of a hot-bottle. In some cases the actual gangrene is determined by thrombosis of the popliteal or tibial arteries, which are already narrowed by obliterating endarteritis.

It is common to find that the patient has been troubled for a long time before the onset of definite signs of gangrene, with cold feet, with tingling and loss of feeling, or a peculiar sensation as if walking on cotton wool.

The first evidence of the death of the part varies in different cases. Sometimes a dark-blue spot appears on the medial side of the great toe and gradually increases in size; or a blister containing blood-stained fluid may form. Streaks or patches of dark-blue mottling appear higher up on the foot or leg. In other cases a small sore surrounded by a congested areola forms in relation to the nail and refuses to heal. Such sores on the toes of old persons are always to be looked upon with suspicion and treated with the greatest care; and the urine should be examined for sugar. There is often severe, deep-seated pain of a neuralgic character, with cramps in the limb, and these may persist long after a line of demarcation has formed. The dying part loses sensibility to touch and becomes cold and shrivelled.

All the physical appearances and clinical symptoms associated with dry gangrene supervene, and the dead portion is delimited by a line of demarcation. If this forms slowly and irregularly it indicates a very unsatisfactory condition of the circulation; while, if it forms quickly and decidedly, the presumption is that the circulation in the parts above is fairly good. The separation of the dead part is always attended with the risk of infection taking place, and should this occur, the temperature rises and other evidences of toxaemia appear.

_Prophylaxis._--The toes and feet of old people, the condition of whose circulation predisposes them to gangrene, should be protected from slight injuries such as may be received while paring nails, cutting corns, or wearing ill-fitting boots. The patient should also be warned of the risk of exposure to cold, the use of hot-bottles, and of placing the feet near a fire. Attempts have been made to improve the peripheral circulation by establishing an anastomosis between the main artery of a limb and its companion vein, so that arterial blood may reach the peripheral capillaries--reversal of the circulation--but the clinical results have proved disappointing. (See _Op. Surg._, p. 29.)

_Treatment._--When there is evidence that gangrene has occurred, the first indication is to prevent infection by purifying the part, and after careful drying to wrap it in a thick layer of absorbent and antiseptic wool, retained in place by a loosely applied bandage. A slight degree of elevation of the limb is an advantage, but it must not be sufficient to diminish the amount of blood entering the part. Hot-bottles are to be used with the utmost caution. As absolute dryness is essential, ointments or other greasy dressings are to be avoided, as they tend to prevent evaporation from the skin. Opium should be given freely to alleviate pain. Stimulation is to be avoided, and the patient should be carefully dieted.

When the gangrene is limited to the toes in old and feeble patients, some surgeons advocate the expectant method of treatment, waiting for a line of demarcation to form and allowing the dead part to be separated. This takes place so slowly, however, that it necessitates the patient being laid up for many weeks, or even months; and we agree with the majority in advising early amputation.

In this connection it is worthy of note that there are certain points at which gangrene naturally tends to become arrested--namely, at the highly vascular areas in the neighbourhood of joints. Thus gangrene of the great toe often stops when it reaches the metatarso-phalangeal joint; or if it trespasses this limit it may be arrested either at the tarso-metatarsal or at the ankle joint. If these be passed, it usually spreads up the leg to just below the knee before signs of arrestment appear. Further, it is seen from pathological specimens that the spread is greater on the dorsal than on the plantar aspect, and that the death of skin and subcutaneous tissues extends higher than that of bone and muscle.

These facts furnish us with indications as to the seat and method of amputation. Experience has proved that in senile gangrene of the lower extremity the most reliable and satisfactory results are obtained by amputating in the region of the knee, care being taken to perform the operation so as to leave the prepatellar anastomosis intact by retaining the patella in the anterior flap. The most satisfactory operation in these cases is Gritti's supra-condylar amputation. Haemorrhage is easily controlled by digital pressure, and the use of a tourniquet should be dispensed with, as the constriction of the limb is liable to interfere with the vitality of the flaps.

When the tibial vessels can be felt pulsating at the ankle it may be justifiable, if the patient urgently desires it, to amputate lower than the knee; but there is considerable risk of gangrene recurring in the stump and necessitating a second operation.

That amputation for senile gangrene performed between the ankle and the knee seldom succeeds, is explained by the fact that the vascular obstruction is usually in the upper part of the posterior tibial artery, and the operation is therefore performed through tissues with an inadequate blood supply. It is not uncommon, indeed, on amputating above the knee, to find even the popliteal artery plugged by a clot. This should be removed at the amputation by squeezing the vessel from above downward by a "milking" movement, or by "catheterising the artery" with the aid of a cannula with a terminal aperture.

It is to be borne in mind that the object of amputation in these cases is merely to remove the gangrenous part, and so relieve the patient of the discomfort and the risks from infection which its presence involves. While it is true that in many of these patients the operation is borne remarkably well, it must be borne in mind that those who suffer from senile gangrene are of necessity bad lives, and a guarded opinion should be expressed as to the prospects of survival. The possibility of the disease developing in the other limb has already been referred to.

[Illustration: FIG. 21.--Embolic Gangrene of Hand and Arm.]

  1. Embolic Gangrene# (Fig. 21).--This is the most typical form of gangrene

resulting from the _sudden_ occlusion of the main artery of a part, whether by the impaction of an embolus or the formation of a thrombus in its lumen, when the collateral circulation is not sufficiently free to maintain the vitality of the tissues.

There is sudden pain at the site of impaction of the embolus, and the pulses beyond are lost. The limb becomes cold, numb, insensitive, and powerless. It is often pale at first--hence the term "white gangrene" sometimes applicable to the early appearances, which closely resemble those presented by the limb of a corpse.

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.

  1. 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.

  1. 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 hyperaemia. 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.

  1. Gangrene from Heat, Chemical Agents, and Cold.#--Severe #burns# and
  2. 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.

  1. 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 anaesthetic 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.

  1. 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 ischaemia 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.

  1. 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, oedema, 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 toxaemia. Occasionally the other limb becomes gangrenous. On the other hand, the glycosuria may diminish or may even disappear after amputation.

  1. 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, anaemia, 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. They last for a few minutes or even for some hours, and as they pass off the parts become hyperaemic and painful.

A more advanced stage of the disease is known as _local asphyxia_. The circulation through the fingers becomes exceedingly sluggish, and the parts assume a dull, livid hue. There is swelling and burning or shooting pain. This may pass off in a few days, or may increase in severity, with the formation of bullae, and end in dry gangrene. As a rule, the slough which forms is comparatively small and superficial, but it may take some months to separate. The condition tends to recur in successive winters.

The _treatment_ consists in remedying any nervous or uterine disorder that may be present, keeping the parts warm by wrapping them in cotton wool, and in the use of hot-air or electric baths, the parts being immersed in water through which a constant current is passed. When gangrene occurs, it is treated on the same lines as other forms of dry gangrene, but if amputation is called for it is only with a view to removing the dead part.

  1. Angio-sclerotic Gangrene.#--A form of gangrene due to _angio-sclerosis_

is occasionally met with in young persons, even in children. It bears certain analogies to Raynaud's disease in that spasm of the vessels plays a part in determining the local death.

The main arteries are narrowed by hyperplastic endarteritis followed by thrombosis, and similar changes are found in the veins. The condition is usually met with in the feet, but the upper extremity may be affected, and is attended with very severe pain, rendering sleep impossible.

The patient is liable to sudden attacks of numbness, tingling and weakness of the limbs which pass off with rest--_intermittent claudication_. During these attacks the large arteries--femoral, brachial, and subclavian--can be felt as firm cords, while pulsation is lost in the peripheral vessels. Gangrene eventually ensues, is attended with great pain and runs a slow course. It is treated on the same lines as Raynaud's disease.

  1. Gangrene from Ergot.#--Gangrene may occur from interference with blood

supply, the result of tetanic contraction of the minute vessels, such as results in ill-nourished persons who eat large quantities of coarse rye bread contaminated with the _claviceps purpurea_ and containing the ergot of rye. It has also occurred in the fingers of patients who have taken ergot medicinally over long periods. The gangrene, which attacks the toes, fingers, ears, or nose, is preceded by formication, numbness, and pains in the parts to be affected, and is of the dry variety.

In this country it is usually met with in sailors off foreign ships, whose dietary largely consists of rye bread. Trivial injuries may be the starting-point, the anaesthesia produced by the ergotin preventing the patient taking notice of them. Alcoholism is a potent predisposing cause.

As it is impossible to predict how far the process will spread, it is advisable to wait for the formation of a line of demarcation before operating, and then to amputate immediately above the dead part.


BACTERIAL VARIETIES OF GANGRENE

The acute bacillary forms of gangrene all assume the moist type from the first, and, spreading rapidly, result in extensive necrosis of tissue, and often end fatally.

The infection is usually a mixed one in which anaerobic bacteria predominate. The anaerobe most constantly present is the _bacillus aerogenes capsulatus_, usually in association with other anaerobes, and sometimes with pyogenic diplo- and streptococci. According to the mode of action of the associated organisms and the combined effects of their toxins on the tissues, the gangrenous process presents different pathological and clinical features. Some combinations, for example, result in a rapidly spreading cellulitis with early necrosis of connective tissue accompanied by thrombosis throughout the capillary and venous circulation of the parts implicated; other combinations cause great oedema of the part, and others again lead to the formation of gases in the tissues, particularly in the muscles.

These different effects do not appear to be due to a specific action of any one of the organisms present, but to the combined effect of a particular group living in symbiosis.

According as the cellulitic, the oedematous, or the gaseous characteristics predominate, the clinical varieties of bacillary gangrene may be separately described, but it must be clearly understood that they frequently overlap and cannot always be distinguished from one another.

  1. Clinical Varieties of Bacillary Gangrene.#--#Acute infective gangrene#

is the form most commonly met with in civil practice. It may follow such trivial injuries as a pin-prick or a scratch, the signs of acute cellulitis rapidly giving place to those of a spreading gangrene. Or it may ensue on a severe railway, machinery, or street accident, when lacerated and bruised tissues are contaminated with gross dirt. Often within a few hours of the injury the whole part rapidly becomes painful, swollen, oedematous, and tense. The skin is at first glazed, and perhaps paler than normal, but soon assumes a dull red or purplish hue, and bullae form on the surface. Putrefactive gases may be evolved in the tissues, and their presence is indicated by emphysematous crackling when the part is handled. The spread of the disease is so rapid that its progress is quite visible from hour to hour, and may be traced by the occurrence of red lines along the course of the lymphatics of the limb. In the most acute cases the death of the affected part takes place so rapidly that the local changes indicative of gangrene have not time to occur, and the fact that the part is dead may be overlooked.

[Illustration: FIG. 22.--Gangrene of Terminal Phalanx of Index-Finger, following cellulitis of hand resulting from a scratch on the palm of the hand.]

Rigors may occur, but the temperature is not necessarily raised--indeed, it is sometimes subnormal. The pulse is small, feeble, rapid, and irregular. Unless amputation is promptly performed, death usually follows within thirty-six or forty-eight hours. Even early operation does not always avert the fatal issue, because the quantity of toxin absorbed and its extreme virulence are often more than even a robust subject can outlive.

_Treatment._--Every effort must be made to purify all such wounds as are contaminated by earth, street dust, stable refuse, or other forms of gross dirt. Devitalised and contaminated tissue is removed with the knife or scissors and the wound purified with antiseptics of the chlorine group or with hydrogen peroxide. If there is a reasonable prospect that infection has been overcome, the wound may be at once sutured, but if this is doubtful it is left open and packed or irrigated.

When acute gangrene has set in no treatment short of amputation is of any avail, and the sooner this is done, the greater is the hope of saving the patient. The limb must be amputated well beyond the apparent limits of the infected area, and stringent precautions must be taken to avoid discharge from the already gangrenous area reaching the operation wound. An assistant or nurse, who is to take no other part in the operation, is told off to carry out the preliminary purification, and to hold the limb during the operation.

  1. Malignant Oedema.#--This form of acute gangrene has been defined as

"a spreading inflammatory oedema attended with emphysema, and ultimately followed by gangrene of the skin and adjacent parts." The predominant organism is the _bacillus of malignant oedema_ or _vibrion septique_ of Pasteur, which is found in garden soil, dung, and various putrefying substances. It is anaerobic, and occurs as long, thick rods with somewhat rounded ends and several laterally placed flagella. Spores, which have a high power of resistance, form in the centre of the rods, and bulge out the sides so as to give the organisms a spindle-shaped outline. Other pathogenic organisms are also present and aid the specific bacillus in its action.

At the bedside it is difficult, if not impossible, to distinguish it from acute infective gangrene. Both follow on the same kinds of injury and run an exceedingly rapid course. In malignant oedema, however, the incidence of the disease is mainly on the superficial parts, which become oedematous and emphysematous, and acquire a marbled appearance with the veins clearly outlined. Early disappearance of sensation is a particularly grave symptom. Bullae form on the skin, and the tissues have "a peculiar heavy but not putrid odour." The constitutional effects are extremely severe, and death may ensue within a few hours.

  1. Acute Emphysematous# or #Gas Gangrene# was prevalent in certain areas

at various periods during the European War. It follows infection of lacerated wounds with the _bacillus aerogenes capsulatus_, usually in combination with other anaerobes, and its main incidence is on the muscles, which rapidly become infiltrated with gas that spreads throughout the whole extent of the muscle, disintegrating its fibres and leading to necrosis. The gangrenous process spreads with appalling rapidity, the limb becoming enormously swollen, painful, and crepitant or even tympanitic. Patches of coppery or purple colour appear on the skin, and bullae containing blood-stained serum form on the surface. The toxaemia is profound, and the face and lips assume a characteristic cyanosis. The condition is attended with a high mortality. Only in the early stages and when the infection is limited are local measures successful in arresting the spread; in more severe cases amputation is the only means of saving life.

  1. Cancrum Oris# or #Noma#.--This disease is believed to be due to a

specific bacillus, which occurs in long delicate rods, and is chiefly found at the margin of the gangrenous area. It is prone to attack unhealthy children from two to five years of age, especially during their convalescence from such diseases as measles, scarlet fever, or typhoid, but may attack adults when they are debilitated. It is most common in the mouth, but sometimes occurs on the vulva. In the mouth it begins as an ulcerative stomatitis, more especially affecting the gums or inner aspect of the cheek. The child lies prostrated, and from the open mouth foul-smelling saliva, streaked with blood, escapes; the face is of an ashy-grey colour, the lips dark and swollen. On the inner aspect of the cheek is a deeply ulcerated surface, with sloughy shreds of dark-brown or black tissue covering its base; the edges are irregular, firm, and swollen, and the surrounding mucous membrane is infiltrated and oedematous. In the course of a few hours a dark spot appears on the outer aspect of the cheek, and rapidly increases in size; towards the centre it is black, shading off through blue and grey into a dark-red area which extends over the cheek (Fig. 23). The tissue implicated is at first firm and indurated, but as it loses its vitality it becomes doughy and sodden. Finally a slough forms, and, when it separates, the cheek is perforated.

Meanwhile the process spreads inside the mouth, and the gums, the floor of the mouth, or even the jaws, may become gangrenous and the teeth fall out. The constitutional disturbance is severe, the temperature raised, and the pulse feeble and rapid.

The extremely foetid odour which pervades the room or even the house the patient occupies, is usually sufficient to suggest the diagnosis of cancrum oris. The odour must not be mistaken for that due to decomposition of sordes on the teeth and gums of a debilitated patient.

The _prognosis_ is always grave in the extreme, the main risks being general toxaemia and septic pneumonia. When recovery takes place there is serious deformity, and considerable portions of the jaws may be lost by necrosis.

[Illustration: FIG. 23.--Cancrum oris.

(From a photograph lent by Sir George T. Beatson.)]

_Treatment._--The only satisfactory treatment is thorough removal under an anaesthetic of all the sloughy tissue, with the surrounding zone in which the organisms are active. This is most efficiently accomplished by the knife or scissors, cutting until the tissue bleeds freely, after which the raw surface is painted with undiluted carbolic acid and dressed with iodoform gauze. It may be necessary to remove large pieces of bone when the necrotic process has implicated the jaws. The mouth must be constantly sprayed with peroxide of hydrogen, and washed out with a disinfectant and deodorant lotion, such as Condy's fluid. The patient's general condition calls for free stimulation.

The deformity resulting from these necessarily heroic measures is not so great as might be expected, and can be further diminished by plastic operations, which should be undertaken before cicatricial contraction has occurred.


BED-SORES

Bed-sores are most frequently met with in old and debilitated patients, or in those whose tissues are devitalised by acute or chronic diseases associated with stagnation of blood in the peripheral veins. Any interference with the nerve-supply of the skin, whether from injury or disease of the central nervous system or of the peripheral nerves, strongly predisposes to the formation of bed-sores. Prolonged and excessive pressure over a bony prominence, especially if the parts be moist with skin secretions, urine, or wound discharges, determines the formation of a sore. Excoriations, which may develop into true bed-sores, sometimes form where two skin surfaces remain constantly apposed, as in the region of the scrotum or labium, under pendulous mammae, or between fingers or toes confined in a splint.

[Illustration: FIG. 24.--Acute Bed-Sores over Right Buttock.]

_Clinical Features._--Two clinical varieties are met with--the acute and the chronic bed-sore.

The _acute_ bed-sore usually occurs over the sacrum or buttock. It develops rapidly after spinal injuries and in the course of certain brain diseases. The part affected becomes red and congested, while the surrounding parts are oedematous and swollen, blisters form, and the skin loses its vitality (Fig. 24).

In advanced cases of general paralysis of the insane, a peculiar form of acute bed-sore beginning as a blister, and passing on to the formation of a black, dry eschar, which slowly separates, occurs on such parts as the medial side of the knee, the angle of the scapula, and the heel.

The _chronic_ bed-sore begins as a dusky reddish purple patch, which gradually becomes darker till it is almost black. The parts around are oedematous, and a blister may form. This bursts and exposes the papillae of the skin, which are of a greenish hue. A tough greyish-black slough forms, and is slowly separated. It is not uncommon for the gangrenous area to continue to spread both in width and in depth till it reaches the periosteum or bone. Bed-sores over the sacrum sometimes implicate the vertebral canal and lead to spinal meningitis, which usually proves fatal.

In old and debilitated patients the septic absorption taking place from a bed-sore often proves a serious complication of other surgical conditions. From this cause, for example, old people may succumb during the treatment of a fractured thigh.

The granulating surface left on the separation of the slough tends to heal comparatively rapidly.

_Prevention of Bed-sores._--The first essential in the prevention of bed-sores is the regular changing of the patient's position, so that no one part of the body is continuously pressed upon for any length of time. Ring-pads of wool, air-cushions, or water-beds are necessary to remove pressure from prominent parts. Absolute dryness of the skin is all-important. At least once a day, the sacrum, buttocks, shoulder-blades, heels, elbows, malleoli, or other parts exposed to pressure, must be sponged with soap and water, thoroughly dried, and then rubbed with methylated spirit, which is allowed to dry on the skin. Dusting the part with boracic acid powder not only keeps it dry, but prevents the development of bacteria in the skin secretions.

In operation cases, care must be taken that irritating chemicals used to purify the skin do not collect under the patient and remain in contact with the skin of the sacrum and buttocks during the time he is on the operating-table. There is reason to believe that the so-called "post-operation bed-sore" may be due to such causes. A similar result has been known to follow soiling of the sheets by the escape of a turpentine enema.

_Treatment._--Once a bed-sore has formed, every effort must be made to prevent its spread. Alcohol is used to cleanse the broken surface, and dry absorbent dressings are applied and frequently changed. It is sometimes found necessary to employ moist or oily substances, such as boracic poultices, eucalyptus ointment, or balsam of Peru, to facilitate the separation of sloughs, or to promote the growth of granulations. In patients who are not extremely debilitated the slough may be excised, the raw surface scraped, and then painted with iodine.

Skin-grafting is sometimes useful in covering in the large raw surface left after separation or removal of sloughs.