Gangrene (GANG-green) is the decay or death of living tissue caused by a lack of oxygen supply to the tissue and/or bacterial infection of the tissue.
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What Is Gangrene?
Gangrene is not a contagious disease. It is a condition in which living tissue (e.g., skin, muscle, or bone) begins to decay and die because blood flow (and oxygen) to an area is blocked or because harmful bacteria invade the body's tissues after entering through a wound or sore. Gangrene most commonly affects the feet, toes, hands, and fingers. Gangrene can also occur inside the body in abdominal organs such as the intestines.
Doctors recognize three major forms of gangrene: dry, wet, and gas gangrene.
Dry gangrene is the most common form of gangrene, and it occurs most frequently in the feet of people with diabetes * . Dry gangrene results from the gradual loss of blood supply to a part of the body. The tissue slowly dies because it receives little or no oxygen and nutrients from the blood, but it does not become infected. The first symptoms of dry gangrene are often numbness and tingling in the affected area. This is usually followed by severe pain as the condition progresses and the tissue begins to die; the skin temperature drops, and the color of the tissue changes, eventually turning black.
Dry gangrene is most often a complication of diabetes, arteriosclerosis * , or frostbite * . Because this condition usually develops gradually, it may go unnoticed for weeks or months, especially in elderly people. Dry gangrene usually is not life threatening, but it needs to be treated promptly.
* diabetes (dye-uh-BEE-teez) is a condition in which the body's pancreas does not produce enough insulin or the body cannot use the insulin it makes effectively, resulting in increased levels of sugar in the blood. This can lead to increased urination, dehydration, weight loss, weakness, and a number of other symptoms and complications related to chemical imbalances within the body.
* arteriosclerosis (ar-teer-e-o-sklah-RO-sis) is a condition in which arteries of the body have become narrowed and hardened from the buildup of calcium, cholesterol, and other substances, causing decreased blood flow through these vessels.
* frostbite is damage to tissues resulting from exposure to low environmental temperatures. It is also called congelation (kon-jeh-LAY-shun).
Wet gangrene is caused by a bacterial infection from severe wounds or burns or by a crushing injury that causes blood to stop flowing to a certain part of the body. When blood flow stops, bacteria begin to invade the damaged tissue. In wet gangrene, there is pain, swelling, and blistering of the skin, and the wound gives off a foul smell. Organisms that are commonly involved in wet gangrene include Streptococcus (strep-tuh-KAH-kus) and Staphylococcus (stah-fih-lo-KAH-kus) bacteria. Without treatment, wet gangrene can be fatal.
Gas gangrene, which is a form of wet gangrene, involves infection of body tissue by certain types of bacteria (such as Clostridium perfringens, klah-STRIH-de-um per-FRING-enz) that are capable of thriving in anaerobic (ah-nuh-RO-bik) conditions (in which there is little or no oxygen). Once present in the tissue, these bacteria release toxins * and gas. Gas gangrene is marked by a high fever, brownish pus * , gas bubbles under the skin, skin discoloration, and a foul odor. It is the rarest form of gangrene, and only 1,000 to 3,000 cases occur in the United States each year. Like wet gangrene, gas gangrene can be fatal if not treated immediately.
How Do Doctors Diagnose and Treat Gangrene?
A doctor will make the diagnosis of gangrene based on a physical examination, the patient's medical history, and the results of blood and other laboratory tests. Cultures from the gangrenous area may be taken and laboratory tests performed to identify the type of bacterial infection and determine the extent to which an infection has spread.
Dead gangrenous tissue must be removed surgically by a procedure called debridement (deh-BREED-ment) so that the wound can heal and healthy new tissue can grow. People with gangrene caused by bacterial infections are treated with antibiotics. In more severe cases, amputation * of a finger, toe, or part of a limb may be necessary. Sometimes patients with gangrene are treated in a hyperbaric chamber, where they are exposed to oxygen at a high pressure to help the affected tissue heal.
* toxins are poisons that harm the body.
* pus is a thick, creamy fluid, usually yellow or greenish in color, that forms at the site of an infection. Pus contains infection-fighting white cells and other substances.
* amputation (am-pyoo-TAY-shun) is the removal of a limb or other appendage or outgrowth of the body.
The outcome for gangrene is usually favorable if the condition is recognized and treated early. Full recovery and new tissue growth can take several weeks to months. Sepsis, a potentially serious spread of infection through the bloodstream and body, can result from wet and gas gangrene. If left untreated, sepsis can result in shock * or death.
Can Gangrene Be Prevented?
Carefully cleaning and watching wounds for signs of infection can help prevent gangrene. It is wise to seek medical attention for any wounds that are not healing well or look infected. People who are susceptible to dry gangrene, such as those with decreased circulation in their legs and feet from diabetes or arteriosclerosis, are advised to pay attention to any skin infection in those areas (because such infections could lead to the development of wet gangrene) and to avoid smoking (because smoking constricts the blood vessels, further decreasing circulation). Daily foot care and hygiene is very important in people with advanced diabetes. Treatment with antibiotics before and after abdominal surgery has been shown to reduce the rate of infection and the possibility of developing wet or gas gangrene.
* shock is a serious condition in which blood pressure is very low and not enough blood flows to the body's organs and tissues. Untreated, shock may result in death.
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