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Third stage
Surgery
Lec-3
.د
زياد
1/1/2014
GANGRENE
It implies death of macroscopic portions of tissue; the term necrosis may be used
synonymously.
Clinical features
A gangrenous part lacks arterial pulsation, venous return, capillary response to pressure,
sensation, warmth and function.
The colour of the part changes through a variety of shades according to circumstances
(pallor, dusky grey, mottled, purple) until finally taking on the characteristic dark-brown,
greenish-black or black appearance, which is caused by the disintegration of hemoglobin
and the formation of Iron Sulphide.
Dry gangrene occurs when the tissues are desiccated by gradual slowing of the
bloodstream; it is typically the result of atheromatous occlusion of arteries. The affected
part becomes dry and wrinkled, discoloured from disintegration of hemoglobin, and greasy
to the touch.
Moist gangrene occurs when infection and putrefaction are present; the affected part
becomes swollen and discoloured and the epidermis may be raised in blebs. Crepitus may
be palpated as a result of infection by gas-forming organisms. This situation is quite
common in diabetics.
Separation of gangrene
A zone of demarcation between the truly viable and the dead or dying tissue will
eventually appear. Separation is achieved by the development of a layer of granulation
tissue, which forms between the dead and the living parts.
In dry gangrene, if the blood supply of the proximal tissues is adequate, the final line
of demarcation appears in a matter of days and separation occurs neatly and with the
minimum of infection (so called separation by aseptic ulceration).
In moist gangrene there is significant infection and suppuration extends into the
neighbouring living tissue, thereby causing the final line of demarcation to be more
proximal than in dry gangrene (separation by septic ulceration). This is why dry
gangrene must be kept as dry and aseptic as possible, and why every effort should be
made to convert moist gangrene into the dry type.
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Treatment of gangrene
This depends on the blood supply proximal to the gangrene. Sometimes this can be
improved by radiological or surgical intervention.
A good blood supply may allow a conservative excision or distal amputation, avoiding a
major ablation. Conservative treatment involves keeping the affected part absolutely
dry. Exposure to the air and the use of a fan may assist in the desiccation process and
may relieve pain.
The limb must not be heated. Local pressure areas, e.g. the skin of the heel or the
malleoli, must be protected if fresh patches of gangrene are not to occur in these
places. Foam blocks and air beds are useful preventative aids. Occasionally, the lifting
of a crust or the removal of hard skin helps demarcation or releases pus and relieves
pain.
a proximal life-saving amputation is required for rapidly spreading symptomatic
gangrene and gas gangrene.
Specific varieties of gangrene
1) Diabetic gangrene
Its related to three factors:
trophic changes from peripheral neuropathy,
ischaemia as a result of atheroma,
and low resistance to infection because of excess sugar in the tissues
Treatment:
bringing the diabetes under control by diet and drugs.
The gangrene is treated as described above.
A rapid spread of infection requires drainage by incision and the removal of any
obviously dead tissue.
2) Bedsores
A bedsore is gangrene caused by local pressure . predisposed by five factors:
pressure, injury, anaemia, malnutrition and moisture.
They can appear and extend rapidly in immobile patients and in those with debilitating
illness.
Prophylactic measures :
the avoidance of pressure over bony prominences by the use of foam blocks or similar,
regular turning, and nursing on specially designed beds.
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Injury from wrinkled sheets and maceration of the skin by sweat, urine or pus must be
prevented by skilled nursing and the use of an adhesive film dressing.
The affected area must be kept dry and an aerosol silicone spray may be used.
Once pressure sores develop, they are difficult to heal. They may be treated by lotions
or by exposure to keep them as dry as possible. They should be kept clean and debrided
if necessary.
Advice from a plastic surgeon should be sought for major lesions; rotation flaps can be
effective.
3) Drug abuse
Inadvertent arterial injection of drugs has become common in many countries with
significant numbers of drug addicts.
Usually, the femoral artery in the groin is involved and presentation is with pain and
mottling distally in the leg.
Fortunately, most cases resolve and progression to gangrene is rare.
It should be remembered that many of these patients carry the human
immunodeficiency virus and/or various hepatitis viruses.
4) Frostbite
Caused by exposure to cold.
Seen both in climbers at high altidudes and in the elderly during cold.
Vessel walls are damaged, leading to transudation and oedema.
The sufferer experiences a severe burning pain in the affected part, which later
assumes a waxy appearance as the pain disappears. Blistering and then gangrene
follow.
Frostbitten parts must be warmed gradually; any temperature higher than that of the
body is detrimental. The part should be wrapped in cotton wool and kept at rest.
Friction, e.g. rubbing with snow, may damage already devitalised tissues. Warm drinks
and clothing should be provided and powerful analgesics given to relieve the pain that
heralds the return of circulation.
Amputations should be conservative.
5) Venous gangrene
Although deep vein thrombosis is common, venous gangrene is surprisingly rare. It
occurs when the circulation of a limb (usually the leg) is disrupted by overwhelming
outflow obstruction and this requires massive deep vein thrombosis at a proximal site.
Treatment
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in those at risk is by full anticoagulation with heparin
effective elevation of the swollen leg, preferably with the head and trunk level.
Some would advocate venous thrombectomy in extreme circumstances using a Fogarty
catheter.
AMPUTATION
Its resection of part or all of a limb.
INDICATIONS :
o Dead (or dying) Peripheral vascular disease accounts for almost 90 % of all
amputations. Other causes of limb death are severe trauma, burns and frostbite.
o Dangerous ‘Dangerous’ disorders are malignant tumours, potentially lethal sepsis
and crush injury.
o Damned nuisance Retaining the limb may be worse than having no limb at all. This
may be because of:
pain
gross malformation
recurrent sepsis or
severe loss of function.
COMPLICATIONS OF AMPUTATION STUMPS
EARLY COMPLICATIONS
In addition to the complications of any operation (especially secondary haemorrhage),
there are two special hazards:
Breakdown of skin flaps This may be due to ischaemia, suturing under excess tension
or (in below-knee amputations) an unduly long tibia pressing against the flap.
Gas gangrene Clostridia and spores from the perineum may infect a high above-knee
amputation (or re-amputation), especially if performed through ischaemic tissue.
LATE COMPLICATIONS
Skin
-Eczema is common, and tender purulent lumps may develop in the groin. A rest from
the prosthesis is indicated.
-Ulceration is usually due to poor circulation, and re-amputation at a higher level is
then necessary. If, however, the circulation is satisfactory and the skin around an ulcer
is healthy, it may be sufficient to excise 2.5 cm of bone and re-suture.
Muscle If too much muscle is left at the end of the stump, the resulting unstable
‘cushion’ induces a feeling of insecurity that may prevent proper use of a prosthesis; if
so, the excess soft tissue must be excised.
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Blood supply Poor circulation gives a cold, blue stump that is liable to ulcerate. This
problem chiefly arises with below-knee amputations and often re-amputation is
necessary.
Nerve a cut nerve always forms a neuroma and occasionally this is painful and tender.
Excising 3 cm of the nerve above the neuroma sometimes succeeds.
Phantom limb the feeling that the amputated limb is still present. appear to have
greater significance in those who also have features of depressive symptoms. The
patient should be warned of the possibility; eventually the feeling recedes or
disappears but, in some, long-term medication may be needed. A painful phantom
limb is very difficult to treat.
Joint The joint above an amputation may be stiff or deformed.
Bone A spur often forms at the end of the bone, but is usually painless. If there has
been infection, however, the spur may be large and painful and it may be necessary to
excise the end of the bone with the spur.