+DISEASES AND INJURIES OF THE ARTERIES AND GANGRENE+
+Gangrene+ is a term employed to denote the death of a part of the body,
in mass.
_Necrosis_ and _mortification_ are terms used in a similar sense
though necrosis is reserved in surgery to mean death of bone.
Gangrene may result from the gradual or sudden cessation of the
arterial supply, or from a stoppage of the venous outflow. In general
the etiology of gangrene comprises:
1. Traumatic causes.
2. Constitutional causes.
3. Thrombosis and embolism.
4. Cold.
5. The effect of certain chemicals.
Before entering into a consideration of these subjects, it is wise to
first consider the varieties of gangrene.
There are two forms in which gangrene is observed: _dry_ and _moist_.
+Dry gangrene+, or mummification, is a condition which occurs in
consequence of a gradual diminution and final cessation of the blood
supply, with the venous outflow intact. In this way, aided by
evaporation and the venous return, there is a gradual drying of the
parts. Diseases of the arteries and increasing pressure upon them from
growing tumors, causes this variety.
+Moist gangrene+ is due to the sudden arrest of the arterial supply, or
a similar obstruction to the venous return.
This is the variety commonly met with from crushing or cutting
accidents; from the effects of carbolic and other acids; from cold;
and from thrombosis and embolism.
A _thrombus_ is a blood clot occluding the lumen of a vessel. An
_embolus_ is a loosened part of a thrombus or any other foreign
substance, free in the blood stream, such as a drop of fat, an air
globule, or a detached particle of tissue from growths in the heart or
vessels. Any one of these may find lodgment in a terminal vessel, and
plug it.
Moist gangrene therefore differs from dry gangrene in that the arrest
of circulation takes place more or less suddenly when the tissues are
suffused with blood.
The dry form of gangrene does not occur regularly in the diseases in
which it might be expected, and though a true wet gangrene is not
found, neither is the typical mummification.
Moist gangrene may occur in diabetes, in senility and in Reynaud’s
disease, and probably assumes this form on account of the sudden onset
of inflammation in the part from some slight abrasion, or from weak
heart action.
C+AUSES OF GANGRENE+
_Traumatic._ The sudden cessation of the blood supply to a part in
consequence of a cutting or crushing accident, will obviously produce
the moist form of gangrene. It is not essential that the part be
entirely severed, or even nearly so, for if only the main artery is
severed, gangrene will ensue.
The crushing or pressure upon a large vein will act similarly, owing
to there being no outflow possible, back pressure will cause the total
arrest of circulation in the part.
_Constitutional Diseases._ Certain diseases affect the lumen or
calibre of the blood vessels, gradually diminishing and finally
arresting the stream of blood carried through them.
In these diseases it would be logical to invariably expect dry
gangrene. This does not regularly occur, for the reason just given,
and the mere presence of a moist or dry condition therefore cannot be
regarded as diagnostic.
In diabetes, either form may obtain, and a diagnosis can be assured by
the discovery of sugar in the urine.
The thickened condition of the arteries leading to senile gangrene
must be thought of and proven in aged subjects. Dry gangrene is the
rule in arteriosclerosis.
Reynaud’s disease, or synthetic gangrene, is due to a vasomotor
spasmodic condition of the terminal vessels and is of central nerve
origin. The tips of the toes and fingers, of both sides, are the most
common sites, though the lobes of the ears, cheeks and tip of the nose
may be affected.
A coldness of the parts, with mottling of blue and white, and a
subsequent diffuse blueness, becoming darker and finally black, are
characteristic signs of this disease, and the dry form of gangrene is
usual.
_Obliterating Endarteritis_, is a condition in which the walls of an
artery become inflamed and thickened, thus obliterating its lumen.
_Thromboangiitis Obliterans_ is similar to the above and differs only
in that a thrombotic growth occurs in an artery obliterating its
lumen.
_Thrombosis and Embolism._ Thrombosis and embolism cause a sudden or
gradual stoppage of the blood stream in a vessel, and in consequence,
either moist or dry gangrene occurs, depending on the time required
for the obstruction to become complete.
The stoppage of the outflow because of thrombosis in a large vein,
will cause moist gangrene; the part being unable to drain, will, by
back pressure, arrest circulation.
_Cold._ Frost bite causes gangrene of varying degrees. A small
circumscribed patch of tissue may succumb, or an entire finger or
extremity may be affected. The variety is invariably moist. The
diagnosis is easily made from the history of exposure (See “Frost
bite”).
_Chemicals._ Carbolic acid, even in weak solution, often causes
gangrene of a finger or toe, because of its frequent use as a wet
dressing, and therefore should never be employed in this manner.
Gangrene of a single part, (especially in a young subject), incident
to a slight injury or infection, should always excite suspicion that
phenol has been employed. Moist gangrene is the rule. The part
presents a hard, shriveled, black appearance which is characteristic.
Weak solutions of other chemicals such as lysol, acetic acid, and
potassium or sodium hydroxide, employed as a wet dressing, are also
capable of producing gangrene.
+Symptoms.+ (_Dry Gangrene_). Typical dry gangrene usually develops in
the toes and the feet, and the principal symptoms which point to its
advent are, coldness, numbness, pain and tingling in the feet and
muscles of the legs. Persons about to be affected with dry gangrene
often complain for months, before any local signs of gangrene are
present, of severe burning pain in the feet at night when warm in bed.
A trivial injury, such as a bruise, the friction of the shoe, or the
cutting of a corn, may act as the exciting cause of the affection. The
part becomes congested and gradually assumes a dark purple color,
finally becoming black and dry; it is insensitive, but the surrounding
parts are congested and may be the seat of intense pain. The dead part
becomes black, shriveled, and dry, and emits little odor.
Dry gangrene usually spreads very slowly; one or two toes may first be
involved and the disease may gradually spread to the rest of the foot
and the leg. There may be little fever at first, but if a large extent
of tissue is involved, a certain amount of fever develops. During the
progress of the disease, pain is usually present to a greater or
lesser degree, sometimes being intense; this is accounted for by the
fact that the nerves are usually the last structures to die.
During the course of the disease, the patient loses much sleep from
continued pain, and becomes worn out and may die of exhaustion.
In dry gangrene there is usually no well marked attempt at the
formation of lines of demarcation and separation, but in some cases,
if the amount of tissue involved is small, say one or two toes, or a
part of the foot, for instance, and if the patient’s strength can be
sustained, the line of separation forms, and the dead tissue may be
cast off, leaving the bones exposed in the wound.
+Moist Gangrene.+ When a part which has had its vitality seriously
interfered with becomes gangrenous, pain, which may have been present,
suddenly ceases, the part becomes insensitive, and the skin is cold,
pale, and mottled purple, green, and red, and finally dark colored;
blebs containing brownish serum form upon the surface; the wound, if
one is present, assumes a grayish color, and an offensive discharge
escapes from it; the dead tissue rapidly undergoes putrefactive
changes. Coincidentally with these changes in the dead tissues, the
living tissue in contact with it becomes red and swollen, and the
separation of the dead tissue from the living is affected by an
ulcerative inflammation, granulations from the living tissue lifting
off the slough.
The patient, at the same time, if the gangrenous process involves any
considerable extent of surface, exhibits the unconstitutional signs of
inflammation (fever, rapid pulse, etc.) and, in some cases, if the
septic infection is intense, may die from septicemia.
In both dry and moist gangrene, when the gangrenous process is
arrested, the dead tissue is separated from the living by a process of
inflammation; the living tissue, at its point of contact with the dead
tissue, and for some distance from it, becomes red and swollen, and
exhibits all the signs of acute inflammation. The line of contact
between the dead and the living tissue is known as _the line of
demarcation_, and the line of granulations which separates the dead
tissue from the living, is known as _the line of separation_.
The separation of the dead tissue is affected by granulations, which
spring up from the living tissue as a result of inflammation, and
there is also a certain amount of pus secreted from the granulations.
In moist gangrene, the lines of demarcation and separation are fairly
well developed. In dry gangrene, on the other hand, these lines are
usually imperfectly developed.
+Early Diagnosis.+ From the foregoing it will be observed that gangrene
is most common in those past middle life, and that its actual onset is
only a stage in an insidious process. This may be either due to
senility or to some constitutional disease. A slight abrasion alone is
sufficient to set up a train of symptoms out of all proportion to the
cause. In such a case, the operation of a small verruca or papilloma
may be followed by a violent inflammatory reaction, with rapid
extension into the entire foot or leg, resulting in gangrene.
Such cases have occurred, but could have been prevented if a proper
survey of the field had been taken and would have saved the
chiropodist much responsibility.
Before operating on subjects past middle life, it should be a routine
practice to note the color and temperature of the foot, both in the
dependent and horizontal positions. The _anterior tibial pulse_ should
also be felt for and its absence or intensity noted. A question to the
patient as to diabetes or thickened arteries may also elicit valuable
information. A very weak or absent anterior tibial pulse (the knack of
feeling the pulse here must be acquired), or peculiar nodules about
the nail grooves, are evidences of an encumbered arterial supply.
Extreme redness or blueness in a foot in the hanging position, and
pallor when elevated, also indicate a similar condition, or one in
which the valves in the veins are impaired.
It is in such conditions that the greatest care should be taken to
avoid deep incisions except in the presence of positive indications.
+Treatment.+ In general, amputation through healthy tissue is the rule
in gangrene affecting any extremity through its entire thickness. The
complete devitalization of even a digital phalanx requires that
amputation be made beyond the next joint above.
In traumatic gangrene it is the rule to amputate immediately through
healthy tissue when restitution of the injured parts is known to be
impossible. In senile gangrene the appearance of the line of
demarcation indicates the extent of the devitalized area and
establishes the point of amputation beyond the next joint above.
Diabetic gangrene presents the peculiarity of a slow and steady
advance, unless an unusually high amputation be performed. Thus, if
the great toe is the site of the beginning of a true diabetic
gangrene, amputation through the lower third of the thigh is
indicated; otherwise the prognosis is very bad.
Inflammatory gangrene, or as it is more properly called _gangrenous
cellulitis_, is a rapidly spreading infective process which destroys
tissue as it advances. It is an acute suppurative process causing
large sloughs. It is a form of cellulitis requiring drainage and
disinfection.
Frost bite may involve tissues to any depth and to any surface extent.
Lesions of circumscribed contour result in the sloughing away of the
area involved and never require amputation. (See “Frost bite.”)
In the event of a phalanx, toe, finger, foot, or hand being involved,
the same rules as above laid down must apply. In this variety,
however, it is important to allow sufficient time to elapse in order
that the depth of the gangrenous process may be ascertained. Should
the line of demarcation be apparent, after a few days the complete
death of the tissues below is certain, and amputation becomes
necessary. If, however, after a few days some slight bleeding or the
appearance of a red point be apparent, the bone, and in all
probability some tissue around it, is still viable. Haste in these
cases should therefore be avoided.