gangrene

Gangrene is the death of tissue due to an interruption of blood flow to that particular area of the body. The condition primarily affects the extremities with the toes being more susceptible than the fingers. It is important to note that you can also have tissue death of the muscles and internal organs as well, but this discussion will be directed toward the toes and feet.

Causes of gangrene include the following:

Risk factors involved in gangrene include:

• age older individuals are more prone to this condition.
• Diabetes can cause tissue death because if your blood sugars are not adequately controlled, the elevated blood sugars eventually damage the blood vessels that supply blood to the feet and toes and cuts off the circulation.
• Arteriosclerosis or hardening of the arteries may also end up blocking blood flow into the toes.
• blue toe syndrome a blood clot into the foot could cause diminished blood flow to the toes.
• Injury including surgery, which traumatizes the skin and underlying tissue may cut off circulation creating lack of circulation to the tissue.

  One of the protocols in foot surgery is to always make sure there is enough distance between two incisions so that the skin in between does not have its circulation cut off and thus die.

• exposure to severe cold (frostbite) which can cause tissue death because extreme cold clamps closed the small vessels going into the toes.
• Immunosuppression may also cause tissue death because immuno-compromised patients have a higher risk of developing infection which then cuts off circulation.

Signs and symptoms of tissue death as it affects the toes

• black or blue discoloration of the skin. Sometimes if there has been trauma to a toe, the black or blue discoloration may be nothing more than dry blood, but it is important for a doctor to check the toe to make sure it is only dry blood.
• severe pain at the end of the toe
• feeling of numbness
• the toe may also be swollen
• drainage coming from the toe
• odor which would indicate the area is probably infected
• Many people will also develop a fever and will have a feeling of not being well.

Tissue death comes in different forms

Dry gangrene is characterized by dry leathery type skin which is usually purplish to black in color. It is seen more in people who have hardening of the arteries. Generally, this type is not infected. In the picture below you can see the distinct demarcation of healthy vs. unhealthy tissue on the great toe. This black area is completely dry and has a leathery texture to it.

Wet Gangrene means that there is a bacterial infection. It is characterized by swelling, drainage, and possible blistering. This is considered a medical emergency and needs to be treated immediately because these infections can spread rapidly. Looking at the picture to the right you will see that it looks similar to the above picture, but it is not. This toe is actively draining exudate (pus) and there is an opening in the toe leading to deeper tissue.

Gas gangrene affects deep muscle tissue that has been deprived of its blood supply either by surgery or trauma. This will occur more in the foot rather than the toes. When the blood supply is cut off to a muscle, a bacteria, Clostridium perfringens, produces a toxin which creates gas under the skin. This will eventually cause tissue death. This is also considered a medical emergency as these infections can also spread very quickly. If you look at the xray below, note the yellow arrow. It is pointing to a cloudy area in the xray which is the gas that is produced from the infection.

As just stated, wet and gas variety are medical emergencies and require immediate care. The dry version also requires medical attention but is usually not an acute emergency but can certainly worsen if not properly treated. In many cases of dry gangrene, particularly in parts of the world not readily accessible to medical care, the dead tissue may just slough off (autoamputation). If the patient is lucky and the area does not get infected the area may heal on its own.

The other two types of gangrene are treated much more aggressively. Untreated gangrene of the wet and gas variety will lead to a worsening of the associated sepsis which can lead to death.

Usually there will be a surgical procedure to remove the "dead" tissue. The surgeon will need to determine the demarcation between where there is no circulation and adequate circulation and the removal of tissue will take place at that junction. If gangrene of a toe is just a symptom of very poor circulation in the leg such as in a diabetic, then an amputation further up the foot or leg may be necessary.

In addition intravenous antibiotics will be administered to clear up any infection. This will all require a hospital stay. Some institutions have begun treating this condition with hyperbaric oxygen which is high pressure oxygen that is delivered to an oxygen deprived area (such as the foot with poor circulation) in an effort to re-introduce oxygen into the tissues that are otherwise not getting enough oxygen due to poor circulation. The idea here is two-fold. One is to give the tissue the oxygen it needs to heal itself and the other is to kill some bacteria known as anaerobic bacteria which thrive in an environment where there is low oxygen tension.

Like most medical conditions, the best way to treat this condition is through prevention.

• avoiding tobacco, which clamps closed your blood vessels is a must.
• Avoiding exposure to cold
• Diabetics need to closely monitor their blood sugars with their doctor in an effort to keep them as close to normal as possible.
• Many diabetics suffer from neuropathy and so it is important they have regular foot exams to make sure there are no problems developing on their feet. If there is a wound that occurs for whatever reason, the patient should see their doctor immediately for proper treatment in an effort to avoid infection.

REFERENCES

Mayo Clinic

Johns Hopkins Medicine

MedLine Plus

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