Gangrene

Gangrene

Also called: Wet Gangrene, Dry Gangrene, Gas Gangrene, Moist Gangrene, Internal Gangrene

Summary

Gangrene is death of tissue, typically due to poor blood supply in a limb or, less often, an internal organ.

The two main types are dry gangrene and wet gangrene. Dry gangrene is caused by lack of blood to a body part. Wet gangrene is caused by a bacterial infection in a part of the body that is experiencing poor circulation. Wet gangrene generally develops faster than dry gangrene and can in some cases be fatal if not treated promptly.

People with diabetes have a greater chance than nondiabetics of developing gangrene because they are prone to conditions that can lead to it. These risk factors include infections, diabetic neuropathy, arteriosclerosis, peripheral arterial disease, skin ulcers, impaired immunity and impaired healing.

The signs and symptoms of gangrene include pain and swelling in the affected area, change of skin color and, in some cases, a putrid smell from the area. A physician usually can diagnose gangrene based on a physical examination. However, further tests may be required to confirm the diagnosis.

Standard treatment includes surgery to remove dead tissue and antibiotics to stop infection. Other treatment options involve therapies using oxygen, infrared light or insect larvae. In some cases, amputation may be required to treat gangrene.

People with diabetes can help prevent gangrene by regularly performing foot care and skin care and by promptly treating minor injuries.

About gangrene

Gangrene is a form of tissue death (necrosis). It typically involves a lack of oxygen-rich blood to a body part, often a limb but sometimes an internal organ. It usually affects soft tissues such as skin and muscle but can also invade bone.

Depending on the type of gangrene involved, it can develop and become life-threatening as quickly as hours after injury or infection, or as long as several weeks. In some cases, drastic treatment methods such as amputation may be avoided if the gangrene is diagnosed quickly.

Gangrene can occur when the circulation of blood is prevented from reaching a certain part of the body. Blood transports oxygen throughout the body. If this supply of oxygen to a body-part is interrupted for any period of time, the tissue begins to die.

Tissue death can progress quickly or slowly depending on the initial cause of the interruption in blood supply. In some cases, gangrene is triggered by a bacterial infection in a part of the body that is experiencing poor circulation. When the bacteria begin to grow, they release toxins that attack the tissue. Gangrene caused by a bacterial infection (called wet gangrene) is usually more aggressive than gangrene caused only by interruption of the blood supply (called dry gangrene).

Gangrene is most common in the lower limbs. The legs and feet are served by fewer blood vessels than most of the rest of the body, which means that it is easier for the blood supply to the lower extremities to be interrupted.

Types and differences of gangrene

There are two main varieties of gangrene: wet gangrene (sometimes also referred to as moist gangrene) and dry gangrene.

Wet gangrene is usually caused by bacterial infection in part of the body that is experiencing reduced blood supply. The affected body part is damp and red and may feel hot. Eventually, it turns cold and blue and emits a foul odor. It is uncommon. However, it can spread quickly and lead to death within days.

Dry gangrene is also caused by reduced flow of blood through the arteries, although infection is not generally involved. The affected tissues become dry and atrophied. The dead (necrotic) tissue is cold, turns black and begins to break down. The necrosis typically spreads upward, toward the center of the body. Pain is common in early stages but may be absent if sensation is severely impaired due to causes such as with diabetic neuropathy. Dry gangrene may take weeks to develop.

A rare but severe type of gangrene is gas gangrene, caused by infection by the bacteria Clostridium. There are at least seven types of Clostridium bacteria that can cause gas gangrene. The most common is C. perfringens. The bacteria cause gas bubbles under the skin that may become blisters. The bubbles under the skin make a characteristic “crackling” sound when they are rubbed. The skin can look pale at first, then turn red, bronze, brown or purple and, in later stages, green. Causes of gas gangrene include necrotizing fasciitis (“fleshing-eating bacteria”) and sudden traumatic injury. It can also occur spontaneously in people with some forms of cancer. It can sometimes lead to death within hours.

Fournier’s gangrene, another rare condition involving necrotizing fasciitis, occurs in the genitals or perianal area. It usually affects men and is reported more in diabetic patients than nondiabetics.

In some cases, gangrene develops in the internal organs, where it may be referred to as internal gangrene. Internal gangrene can result when an organ becomes deprived of oxygen. For example, if a part of the intestine becomes twisted, the blood supply may be stopped. Over time, this could result in gangrene. Alternatively, in some cases, internal organs become infected with Clostridium bacteria and develop gas gangrene.

Risk factors and causes of gangrene

Gangrene is typically caused by lack of blood supply to a part of the body. Without a constant supply of oxygen-rich blood, soft tissues begin to die. In addition, parts of the body that are deprived of oxygen may be more susceptible to bacterial infections that can trigger or quicken tissue death. An insufficient blood supply usually occurs after injury or disease. It may also follow surgery.

Many factors can interrupt the blood supply, including:

  • Impaired circulation. Certain medical conditions can interfere with circulation of blood. Because the legs and feet are served by fewer blood vessels than most of the body, impaired circulation is more likely to result in gangrene of these areas. Conditions that may impair circulation include peripheral arterial disease (PAD, a type of atherosclerosis), diabetic angiopathy, blot clots and other obstructions, and conditions such as Raynaud’s phenomenon. Additionally, some surgical wounds may have an inadequate blood supply that may result in gangrene.
  • Crushing injury and trauma. These are injuries that are caused by the crushing of a body part, therefore cutting off the blood supply. This type of trauma is commonly caused by automobile accidents. Other causes may include industrial or war-related accidents.
  • Thermal injury. In some cases, severe burns or frostbite (frozen body tissue) can result in a lack of oxygen to affected parts of the body. In most cases, burns and frostbite can be treated to prevent further damage. Untreated severe burns or frostbite are likely to result in gangrene.
  • Medications. In rare cases, vasoconstrictors (drugs that narrow the blood vessels) can reduce circulation enough to kill tissues.

People with diabetes are at increased risk of gangrene because they are more likely than nondiabetics to develop conditions that predispose it. For example, diabetic patients are at a high risk for foot conditions and skin conditions, such as ulcers, and for vascular diseases such as PAD. Narrowing of arteries in the legs (lower-extremity PAD) is the type of PAD that, left untreated, most often leads to gangrene.

Diabetic neuropathy (nerve damage caused by diabetes) makes people with diabetes more susceptible to injuries and less likely to notice or treat injuries early. This also increases the risk of gangrene among people with diabetes. Additionally, people with diabetes typically have compromised immune systems and experience hyperglycemia (high blood sugar), which feeds infectious organisms that can increase the risk of gangrene and hinder healing.

Additional risk factors for gangrene include:

  • Immune disorders, such as AIDS
  • Immune suppression caused by chemotherapy for cancer
  • Inflammatory diseases
  • Abuse of alcohol or intravenous drugs
  • Smoking and caffeinated beverages (constrict blood vessels)

Gangrene is generally not contagious, although caregivers should be cautious (e.g., washing hands, wearing gloves) when handling infected body parts.

Signs and symptoms of gangrene

Initial signs and symptoms of gangrene depend on its type, location and cause.

People with dry gangrene (which does not involve a bacterial infection) may initially notice pain in the affected body part. However, people with impaired sensation due to factors such as diabetic neuropathy may not feel pain. Affected tissue dies and becomes very dry, and may be distinguished from adjacent tissue by a line of inflammation. The affected area may become cold to the touch and will turn pale. Eventually, the affected area will darken to brown and then black. If left untreated, the dead skin and muscle will separate from living tissue and fall away from the body.

The signs and symptoms of wet gangrene are slightly different from those of dry gangrene. Wet (moist) gangrene generally develops after a blister, ulcer or other wound becomes infected with bacteria. The patient may feel severe pain, warmth and swelling in the affected area. The skin color may also change to red or bronze as the tissue beneath the skin begins to die. There may be a foul-smelling discharge from the wound.
People who are infected with bacteria that cause gas gangrene may also notice gas bubbles beneath the skin that make a characteristic crackling sound when pressed.

In many cases of wet gangrene and gangrene of internal organs, the bacteria quickly spread throughout the body and cause a systemic infection. Signs and symptoms of this may include:

  • Fever. This may be low-grade early in the disease.
  • Rapid heartbeat (tachycardia). A heart rate over 100 beats a minute in adults.
  • Elevated leukocyte (white blood cell) count.
  • Anemia. Low count of red blood cells.
  • Low blood pressure (hypotension).
  • Edema (swelling).
  • Confusion.

Severe cases of untreated gangrene can lead to kidney failure, shock, delirium, unconsciousness or death.

Anyone who experiences the symptoms of gangrene should consider it a medical emergency and seek immediate medical care. Some forms of gangrene are aggressive and can result in amputation, coma or death if not treated within hours of symptoms appearing.

Diagnosis methods for gangrene

Gangrene is usually apparent upon visual inspection during a physical examination. The physician may conduct a medical history to determine whether the patient has had any recent accidents or other trauma and whether the patient has diabetes or other medical conditions that would increase the risk of gangrene.

Methods used to confirm diagnosis include:

  • Blood tests. These may reveal abnormalities including anemia and an elevated count of white blood cells.
  • X-rays. These radiology tests might reveal gas under the skin in cases of gas gangrene.
  • CAT scan (computed axial tomography), MRI (magnetic resonance imaging) or bone scan. These imaging tests may reveal extent of tissue damage, or may be used to identify other internal conditions that may be responsible for a patient’s symptoms.
  • Tissue analysis. Examination of a sample of dead tissue or blister fluid may reveal type of infectious organism.
  • Angiography. Also called arteriography, this test uses a x-rays and an injected dye called a contrast medium to view arteries. It may be used to diagnose blockages in the arteries and to plan treatment.

Treatment and prevention of gangrene

Successful treatment of gangrene depends on how aggressive the gangrene is and how much damage has been done to the affected body part. It also depends on the patient’s general health.

Patients who have early-stage dry gangrene may be treated by removing the dead (necrotic) tissue and preventing the spread of gangrene. Necrotic tissue and any foreign matter must be removed before healing can occur. Excision may be done under local, regional or general anesthesia depending on the severity of the gangrene and the extent of tissue involvement. Antibiotics may be given to people with dry gangrene to prevent bacterial infection.

Patients with wet gangrene (gangrene usually caused by a bacterial infection) may be administered intravenous penicillin or other antibiotics to attempt to stop the infection. However, in many cases of wet gangrene, the infection may be too severe to effectively treat with antibiotics. Other methods to treat and control gangrene include:

  • Hyperbaric oxygen therapy. Use of high-pressure oxygen to attack infection. The patient may be placed in the same type of oxygen chamber used to treat scuba divers who have “the bends” (decompression sickness). Hyperbaric chambers are available at some hospitals. Research is continuing on its effectiveness in controlling infection.
  • Maggot therapy (also called larval therapy). The medicinal use of tiny blowfly larvae to eat dead tissue and infectious organisms. Some physicians have revived this ancient treatment as more bacteria have become resistant to antibiotics. It is more likely to be used with chronic infections after other treatments have failed. It is reported to be highly effective in some cases.
  • Infrared light therapy. A recent innovation is a light-emitting device approved by the Food and Drug Administration (FDA). The gadget features a pad strapped to the injured area. Dozens of diodes in the pad send painless infrared light into the body. The light is said to dilate the blood vessels, encourage new blood vessels to grow and promote wound healing.
  • Amputation. If all other options fail, surgical removal of part or all of a gangrenous body part may be necessary. This may involve the toes, foot or leg. It may also involve the fingers, hand or entire arm, depending on the extent of the gangrene. In many cases, this controls the spread of gangrene.

In some cases, gangrene results in death. This is especially likely if the gangrene is left untreated for long periods of time, increasing the possibility of a systemic infection. Some forms of gangrene can be fatal if not treated within a few hours of symptom onset.

In many cases, gangrene can be prevented by eliminating risk factors in an individual. Medical conditions, such as artheriosclerosis and peripheral arterial disease (PAD), should be treated to reduce the risk of poor circulation. Additionally, patients should treat all injuries as soon as possible to prevent infections. A physician may recommend that some patients be given antibiotics following surgery to prevent the risk of infection.

People with diabetes should take extra precautions to prevent gangrene. This includes:

  • Control of glucose (blood sugar) and other diabetic risk factors
  • A program of daily foot care, hygiene and inspections
  • A program of daily skin care
  • Periodic complete foot exams by a physician
  • Prompt treatment of blisters, nicks and other minor wounds
  • Notifying a physician if a sore worsens

Questions for your doctor about gangrene

Preparing questions in advance can help patients have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions about gangrene:

  1. Am I at risk for gangrene?

  2. Could my symptoms be due to gangrene? What else might be causing them?

  3. Can you diagnose gangrene with a physical exam, or will I need to have tests?

  4. What type of gangrene do I have?

  5. What caused my gangrene?

  6. What are my treatment options?

  7. What is my prognosis?

  8. If I am at risk of amputation, can anything be done to avoid the need for this surgery?

  9. What risks would delaying treatment pose for me?

  10. How can I reduce my risk of gangrene? Do I need to improve my diet and exercise habits? Do I need to improve control of my glucose, blood pressure, cholesterol or anything else?

  11. What sort of routine foot care and skin care should I perform?

  12. How often should I have a comprehensive foot examination?
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