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Revision as of 16:19, 29 November 2004 by Korath (talk | contribs) (→Dry gangrene: sp)(diff) ← Previous revision | Latest revision (diff) | Newer revision → (diff)Gangrene, also known as tissue necrosis, is the death and subsequent decay of body tissues caused by many number of things including infection, thrombosis and lack of blood flow. It is most commonly the result of critically insufficient blood supply sometimes caused by an injury and subsequent contamination of the wound with bacteria. This condition is most common in the extremities. If conservative management fails, treatment is by amputation. The best weapon against gangrene is prevention, such as scrupulous foot care for diabetics.
Types
Gangrene can be caused from a bacterial infection that has not been treated; this is wet gangrene. When caused by a decrease in blood flow to an area of the body where the tissue in this part of the body has been injured or diseased, the diagnosis is dry gangrene.
One specific example of gangrene is so called diabetic foot that can be seen in long-standing complicated diabetes. It is caused by a combination of arterial ischemia, injury and poor healing that is rather common in diabetics. It often combines poor healing with a superimposed infection.
History
In the years before antibiotics, fly maggots were commonly used to treat wounds to prevent or stop gangrene, as they would only consume dead flesh. Their use largely died out after the introduction of antibiotics. In recent years, however, maggot treatment has regained some credibility and is sometimes employed to great effect in cases of chronic tissue necrosis.
Pathophysiology
Wet gangrene
Wet gangrene is the type of gangrene we are most familiar with, yet it is not the most common. We are familiar with it because old western movies would have a scene where someone would get cut on the leg and it would get infected and soon become gangrene. A doctor would have to saw off their leg while they were biting a bullet and drinking whisky.
Wet gangrene is, in fact, caused by an injury such as a cut or open wound that becomes infected with a bacteria. The infection gets full of pus and does not drain well, blocking off the blood supply and the oxygen to that part of the body, soon the tissue dies. If left untreated the area will become shrunken and black and could continue spreading to other parts of the body. Treatment with antibiotics to kill the bacteria is often necessary and surgically removing the blackened tissue will cease the spread of the infection. Amputation is rarely necessary if caught in the early stages. Disinfecting and keeping wounds clean can prevent them from turning into gangrene.
Dry gangrene
Dry gangrene does not involve a bacterial infection of an open wound. It is caused by the blood flow being stopped or reduced to an area of the body from an injury or disease. This area becomes oxygen deprived and turns black and shrinks when the tissue dies.
Dry gangrene can be caused by an injury which cuts off the supply of blood. An injury can be a blunt trauma, usually to the toes or feet. When this kind of trauma occurs it may involve an acute arterial obstruction, blocking the blood supply. If you get injured and the area becomes painful, red, and swollen and then starts to smell funny it could be gangrene. Surgery may be needed to unblock the arterial obstruction. The sooner this is caught the better the prognosis will be.
Sometimes dry gangrene can be caused by frostbite. The area becomes so cold it gets deprived of oxygen and dies. Frostbite gangrene will not spread to other parts of the body. With frostbite you may feel numbness in the area but when the flesh dies it will become very painful. Once the tissue is dead it will be numb again and darken over time.
Other causes of dry gangrene are diabetes due to poor circulation of the blood to the extremities. Also, any kind of disease with poor circulation, hardening of the arteries, AIDS or arterial embolism can cause gangrene.
The signs that dry gangrene is beginning are a dull, aching pain and coldness in the area. The area may get a sickly pallor to it. If gangrene is developing slowly it can be reversed by surgery. Treatment of poor circulation to prevent tissue from dying can be done in a hyperbaeric oxygen chamber prior to gangrene setting in. The patient goes into a chamber with richer oxygen level than we normally breathe to quickly oxygenate the blood. Treatment in the chamber is usually done once a day for months at a time. It is a very costly treatment, with many other healthy benefits due to the rich oxygen your body receives.
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