Gangrene

Picture of gangrene of the foot.

Gangrene is a medical term used to describe the death of an area of the body. It develops when the blood supply is cut off to the affected part as a result of various processes, such as infection, vascular (pertaining to blood vessels) disease, or trauma. Gangrene can involve any part of the body; the most common sites include the toes, fingers, feet, and hands.

Two major types of gangrene exist:

• Dry gangrene is caused by a reduction of blood flow through the arteries. It appears gradually and progresses slowly. In most people, the affected part does not become infected. In this type of gangrene, the tissue becomes cold and black, begins to dry, and eventually sloughs off. Dry gangrene is commonly seen in people with blockage of arteries (arteriosclerosis) resulting from increased cholesterol levels, diabetes, cigarette smoking, and genetic and other factors.
• Wet or moist gangrene develops as a complication of an untreated infected wound. Swelling resulting from the bacterial infection causes a sudden stoppage of blood flow. Cessation of blood flow facilitates the invasion of the muscles by the bacteria and the multiplication of the bacteria because disease-fighting cells (white blood cells) cannot reach the affected part.
  • Gas gangrene is a type of wet gangrene caused by the bacteria known as Clostridia. Clostridia are a type of infection-causing bacteria that grow only in the absence of oxygen. As Clostridia grow, they produce poisonous toxins and gas; therefore, the condition is called gas gangrene.

The following conditions are risk factors for the development of gangrene:

• Injury or trauma, such as a crush injury, a severe burn, or frostbite
• Diseases that affect the circulation of blood, such as arteriosclerosis, diabetes, smoking, or Raynaud's disease
• Infection of wounds

• Dry gangrene:
  • The affected area becomes cold and numb.
  • Initially, the affected area becomes red.
  • Then, it develops a brown discoloration.
  • Finally, it becomes black and shriveled.
• Wet or moist gangrene:
  • The affected area becomes swollen and decays.
  • It is extremely painful.
  • Local oozing occurs.
  • It produces a foul-smelling odor.
  • It becomes black.
  • The affected person develops a fever.
• Gas gangrene:
  • The wound is infected.
  • A brown-red or bloody discharge may ooze from the affected tissues.
  • Gas produced by Clostridia may produce a crackling sensation when the affected area is pressed.
  • It becomes swollen, and blisters may develop.
  • Pain in the affected area is severe.
  • The affected person develops a fever, increased heart rate, and rapid breathing if the toxins spread into the bloodstream.

Consult a healthcare provider immediately if the following signs develop:

• An area of the body turns blue or black.
• A wound does not heal in seven to 14 days.
• Pain in a localized area is severe.
• Unexplained fever is persistent.
• Pus or blood drains from the wound.
• A foul-smelling odor discharges from the wound.

The diagnosis of gangrene is based on history, physical examination, blood tests, and other exams.

• The healthcare provider asks the person about any history of injury, chronic diseases (such as diabetes), surgery, cigarette smoking, and exposure to extreme cold.
• A physical examination of the affected area is performed to look for signs of gangrene.
• Blood test results show an increase in the number of white blood cells in persons with wet gangrene or infection.
• A sample of the drainage from the wound is examined to identify the bacteria causing the infection.
• An X-ray film may be performed to examine the affected tissue for the presence of gas bubbles or for bone involvement or osteomyelitis.
• Imaging studies, including a CT scan and/or MRI, can help determine the extent of damage to the tissues and the amount of gas present.

In people with dry gangrene, an arteriogram may be performed to visualize any obstruction in the artery which supplies blood to the affected part.

People with gangrene require urgent assessment and treatment to prevent the spread of gangrene. Antibiotics and surgery are the primary treatments and have been proven very effective. Hospitalization is necessary for treatment.

Dry gangrene: Because the cause of dry gangrene is a lack of blood flow, restoring the blood supply is vital. Assessment by a vascular surgeon can help determine whether surgical intervention to restore blood supply would be beneficial.

Wet gangrene: Surgical debridement (removal of dead tissue) of the wound is performed, and intravenous antibiotics are administered to control the infection.

Gas gangrene: This condition needs to be treated aggressively because of the threat of the infection rapidly spreading via the bloodstream and damaging vital organs. The wound requires immediate debridement. Antibiotics are administered to the affected person.

• Antibiotics are usually administered intravenously to control the infection.
• Pain relievers are administered as necessary.
• Anticoagulants are administered to prevent blood clotting.
• Intravenous fluids are administered to replenish electrolytes.

The wound is cleared of dead tissue (debrided) to allow healing and to prevent the spread of infection to surrounding areas.

If the infection cannot be controlled with debridement and administration of antibiotics, amputation of the affected part becomes necessary to prevent further deterioration.

Hyperbaric oxygen is delivered through a specially designed chamber that contains oxygen under high pressure.

• Hyperbaric oxygen has been shown in some studies to improve wound healing, and it ensures that bacteria that thrive only in an oxygen-free environment (anaerobic bacteria) will be killed.
• However, this therapy is not available in all medical centers.
• People receiving hyperbaric oxygen therapy must be monitored for symptoms of oxygen toxicity, such as profuse sweating, difficulty breathing, and convulsions.

• Keep the affected area clean.
• Follow the healthcare provider's instructions regarding changing bandages and dressings.
• Be sure to complete the antibiotic course that is prescribed.
• Limit activity as much as possible for a few days.

The best weapon against gangrene is prevention.

• Keep wounds clean and sterile by cleaning all wounds thoroughly with an antiseptic solution.
• Watch for signs of infection, such as pus, redness, swelling, or unusual pain.
• Consult a healthcare provider if any wound becomes infected.
• People with diabetes should control their blood sugar levels with proper medication.
• Education about proper foot care is vital for people with diabetes. They should routinely examine their feet for any signs of injury or change in skin color. Any minor injury should be immediately cared for. They should keep their nails trimmed and wear comfortable well-fitting shoes.

The outlook for a person with gangrene depends on the following factors:

• Part of the body affected
• The extent of gangrene
• The cause of gangrene
• The overall health status of the individual

The prognosis is generally favorable except in people in whom the infection has spread through the bloodstream. Gangrene is usually curable in the early stages with intravenous antibiotic treatment and debridement. Without treatment, gangrene may lead to a fatal infection.

Gas gangrene can progress quickly; the spread of infection to the bloodstream is associated with a significant death rate. However, if it is diagnosed and treated early, approximately a majority of people with gas gangrene survive without the need for any amputation.

People with dry gangrene most often have many other health problems that complicate recovery, and other system failures usually prove fatal rather than the gangrene itself.