Gangrene

Definition

Gangrene is the medical term for the death of soft tissue as a result of the

loss of blood supply to the affected part of the body. The loss of blood

supply in turn can result from a disorder of the circulatory system, from

trauma, or from infection. Gangrene most commonly involves the fingers,

toes, hands, or feet, but can also develop within the internal organs.

There are two major types of gangrene, dry and wet. Dry gangrene is

caused by a gradual loss of blood flow through the arteries. It typically

develops slowly over a period of years as the person

impaired by atherosclerosis (hardening of the arteries), diabetes, or

long-term smoking.

Wet gangrene develops much more rapidly than dry gangrene. It is

caused by an untreated wound infection or by bacteria growing in tissue

that has broken down as a result of pressure. Bedsores are a type of wet

gangrene that may develop in patients who are bedridden for long periods

of time.

Gas gangrene is a deadly subtype of wet gangrene caused by bacteria

known as

in the absence of oxygen. It produces gas as well as toxins; these compounds

expand and spread rapidly through nearby tissues. Gas gangrene

is a medical emergency.

Description

Dry gangrene typically begins in the parts of the hands and feet that are

furthest from the trunk of the body. These are the parts that are most likely

to lose their blood supply in patients with diseases that affect the circulatory

system. The affected area becomes cold and numb; it begins to turn red as

the blood cells inside the smaller vessels begin to break down. It then turns

a darker brown or blackish color. The dead tissue may eventually fall off if

it is not removed by surgery first.

Wet gangrene develops when the blood flow to the affected body part

is blocked

tissues supports the rapid growth of bacteria, which causes the tissues to

swell and produce a foul-smelling discharge. The affected area is usually

discolored and very painful, and the patient typically develops a fever. If

the gangrene is not treated, the bacterial infection can spread throughout

the body via the bloodstream and kill the patient. The possibility of death

from spreading infection is the reason why military surgeons from the time

of Augustus Caesar through the end of the nineteenth century routinely

amputated the limbs of wounded soldiers; the operations were necessary

to give the soldiers a chance to survive injuries to their arms or legs.

Gas gangrene is a type of wet gangrene caused by

a bacterium that grows in the absence of oxygen. In addition to

swelling and pain in the affected area, the tissue may also crackle or make

a popping sound if the doctor presses on the affected area. The patient

will become very sick very quickly with gas gangrene, often going into

shock, sweating heavily, and developing mental symptoms (confusion

and disorientation).

Demographics

The frequency of gangrene depends on the type. Gas gangrene is fortunately

rare in the United States, with an average of 900 to 1,000 cases

reported each year. According to the National Institute of Diabetes and

Digestive and Kidney Diseases (NIDDK), about 71,000 amputations

of the feet and lower legs are performed each year in the United States

on diabetics who have developed gangrene. More than 60 percent of all

nontraumatic lower-limb amputations in the United States occur in

people with diabetes.

Both wet and dry gangrene affect both sexes and all races equally.

Risk factors for gangrene include:

•leading to gangrene or to be confined to bed and develop bedsores.

Old age. The elderly are more likely to develop circulatory disorders

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•blood vessels to narrow, reducing the supply of oxygen to body

tissues.

Diabetes. Diabetes tends to weaken the blood vessels over time.Diseases of the blood vessels.HIV infection.Radiation or chemotherapy for cancer.Severe injury, including frostbite.Long-term smoking. The chemicals in tobacco smoke cause the

Causes and Symptoms

The basic cause of gangrene is the loss of blood supply to the soft tissues

in a part of the body. This loss may result from circulatory disorders,

from traumatic injury, or from infection.

The basic symptoms of wet and dry gangrene have already been

described. Gangrene is a serious condition, and anyone with any of the

following symptoms should see their doctor at once:

•appearance of the wound.

Pain in the affected area that is out of proportion to the outward

•gas gangrene, the discharge has a mousy or slightly sweet odor.

A foul-smelling ooze or discharge leaking from a wound or sore. In

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Diagnosis

Skin that is colorless, pale, cold, and numb.Skin that is turning blue, brown, or black.

The diagnosis of gangrene is based on a combination of the patient

a physical examination, a blood test, and imaging studies. The

doctor will ask the patient about any recent injuries, exposure to extreme

cold, recent surgery, chronic diseases (particularly diabetes), smoking

habits, and any disorders that affect the immune system. The physical

examination will include examination of the affected body part as well

as taking the patient

Tests and imaging studies that are usually done to evaluate gangrene

include.

•indicates an infection. A blood test may also be done to identify

the specific bacterium causing the infection (in wet gangrene).

Blood test. A higher than normal white blood cell count usually

•soft tissue when gas gangrene is suspected.

X-ray study. This test may be performed to look for gas bubbles in

•(MRI). These tests may be ordered to check for the spread

of gangrene.

Computed tomography (CT) scans and magnetic resonance imaging

•on an x-ray is injected into the patient

help the doctor determine whether any of the patient

blocked. This type of test is usually done for patients with dry

gangrene.

Arteriogram. An arteriogram is a test in which a dye that shows up’s blood circulation. It can’s arteries are

•examined under the microscope for signs of tissue death.

Removal of a sample of the affected tissue. The sample can be

•be cultured in a laboratory to look for signs of

gas gangrene is suspected.

In some cases the patient may be taken directly into surgery to determine

how far the gangrene has spread inside the body.

Removal of a sample of fluid from the affected area. The fluid canC. perfringens when

Treatment

Gangrene is a serious condition requiring treatment in a hospital.

A patient diagnosed with dry gangrene will be assessed by a surgeon who

specializes in vascular disorders to determine whether it is possible to

restore blood flow to the affected area. The tissue that has already died,

however, is usually removed surgically.

Wet gangrene requires immediate treatment with intravenous antibiotics

to stop the spread of infection and debridement (surgical removal

of the dead tissue). If the affected area is large, the patient may need a

skin graft to restore the appearance of the limb. In severe cases, the

patient

spread of infection to vital organs.

Gas gangrene is a medical emergency. The patient is given intravenous

antibiotics while the wound is debrided. Following surgery, the

patient may be placed in a hyperbaric oxygen chamber, a room in which

pure oxygen under pressure is delivered to the patient. Hyperbaric

oxygen raises the oxygen levels in the patient

help to fight the bacteria that cause gas gangrene.

’s blood, which in turn may

Prognosis

The prognosis depends on the type of gangrene, the length of time before

the patient sought treatment, and the patient

conditions, and immune status. Dry gangrene usually has a better prognosis

than wet gangrene because it does not involve infection. Gas gangrene

has a mortality rate ranging from 25 percent in otherwise healthy

patients to 67 percent in patients being treated for cancer.

’s age, underlying medical

Prevention

All people can prevent gangrene by cleansing wounds promptly with an

antiseptic; by watching for signs of infection in the wound (pus, redness,

swelling, and unusual pain); and by going to the doctor at once if a

wound looks infected.

People with diabetes need to take special care to prevent gangrene

in the feet, which is a potential complication of the disease. The reason

for this complication is that diabetes sometimes affects the nerves in the

feet, causing a loss of sensation. The diabetic person may not notice a

cut or other injury to the foot because they cannot feel it. An infection

can then develop and lead to gangrene. NIDDK recommends that

people with diabetes take the following precautions to prevent gangrene

in their feet:

•completely, particularly between the toes.

Wash the feet in warm (not hot) water every day and dry them

•or toenail problems.

Check the feet every day for cuts, blisters, swelling, redness, calluses,

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•wearing sandals.

Cut the toenails once a week after washing the feet.Always wear shoes or slippers to protect the feet from injuries.Always wear socks or stockings to prevent blisters, even when

•sure there are no rough edges that might injure the feet.

The Future

Gangrene will always be a potential complication of traumatic injuries as

well as such chronic diseases as diabetes and HIV infection. Recent

advances in wilderness and battlefield medicine have reduced the risk

of gangrene in injured hikers, explorers, and military personnel. Current

clinical trials are evaluating the effectiveness of new antibiotics in treating

diabetic foot gangrene and of hyperbaric oxygen therapy in treating gas

gangrene.

SEE ALSO

Diabetes; Frostbite; Necrotizing fasciitis

For more information

BOOKS

Dvorchak, George.

of Outdoor Emergencies

Giesbrecht, Gordon G.

Survival, Rescue and Treatment

Books, 2006.

The Pocket First-Aid Field Guide: Treatment and Prevention. Accokeek, MD: Stoeger Publishing Company, 2007.Hypothermia, Frostbite, and Other Cold Injuries: Prevention,. 2nd ed. Seattle, WA: Mountaineers

WEB SITES

eMedicine Health.

.com/gangrene/article_em.htm (accessed August 5, 2008).

Mayo Clinic.

gangrene/DS00993 (accessed August 5, 2008).

National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK).

Gangrene. Available online at http://www.emedicinehealthGangrene. Available online at http://www.mayoclinic.com/health/

Prevent Diabetes Problems: Keep Your Feet and Skin Healthy

at http://diabetes.niddk.nih.gov/dm/pubs/complications_feet/ (accessed

August 6, 2008).. Available online

WORDS TO KNOW
Amputation: Surgical removal of a limb.
Bedsore: A type of wet gangrene that develops
when a bedridden person cannot turn over to
relieve pressure on soft tissue caused by the
weight of the body. Bedsores are sometimes
called pressure ulcers.
Debridement: The medical term for the surgical
removal of dead or damaged soft tissue.
Wear shoes that fit well, and check them before wearing to make’s toes, fingers, or limbs may have to be amputated to prevent the’s history,’s pulse, temperature, and blood pressure.—often by a traumatic injury—the blood that collects in the softClostridium perfringens,’s circulation isClostridium perfringens. C. perfringens is an organism that grows

Gangrene