Gangrene is a complication of necrosis (i.e., cell death) characterized by the decay of body tissues, which become black and malodorous. It is caused by infection or ischemia, such as from thrombosis (blocked blood vessel). It is usually the result of critically insufficient blood supply (e.g., peripheral vascular disease) and is often associated with diabetes and long-term smoking. This condition is most common in the lower extremities. The best treatment for gangrene is revascularization (i.e., restoration of blood flow) of the affected organ, which can reverse some of the effects of necrosis and allow healing. Other treatments include debridement and surgical amputation. The method of treatment is generally determined depending on location of affected tissue and extent of tissue loss. Gangrene may appear as one effect of foot binding.

Etymology

The etymology of gangrene derives from the Latin word "gangraena" and from the Greek gangraina (?????????), which means "putrefaction of tissues".

History

As early as 1028, when antibiotics had not yet been discovered, fly maggots were commonly used to treat chronic wounds or ulcers to prevent or arrest necrotic spread, as some species of maggots consume only dead flesh, leaving nearby living tissue unaffected. This practice largely died out after the introduction of antibiotics and enzyme to the range of treatments for wounds. Recently, however, maggot therapy has regained some credibility and is sometimes employed with great efficacy in cases of chronic tissue necrosis.

Types of gangrene

Dry gangrene

Diabetic ulceration with central "dry" gangrene and toward the edges wet gangrene with some ascending cellulitis

If the blood flow is interrupted for a reason other than severe bacterial infection, the result is a case of dry gangrene. People with impaired peripheral blood flow, such as diabetics, are at greater risk of contracting dry gangrene.

The early signs of dry gangrene are a dull ache and sensation of coldness in the affected area along with pallor of the flesh. If caught early, the process can sometimes be reversed by vascular surgery. However, if necrosis sets in, the affected tissue must be removed just as with wet gangrene.

Wet gangrene

Diabetic with severe infection and loss of toes - wet gangrene in center

Gas gangrene

Gas gangrene is a bacterial infection that produces gas within tissues. It is a deadly form of gangrene usually caused by Clostridium perfringens bacteria. Infection spreads rapidly as the gases produced by bacteria expand and infiltrate healthy tissue in the vicinity. Because of its ability to quickly spread to surrounding tissues, gas gangrene should be treated as a medical emergency.

Gas gangrene is caused by a bacteria exotoxin-producing clostridial species, which are mostly found in soil and other anaerobes (e.g. Bacteroides and anaerobic streptococci). These environmental bacteria may enter the muscle through a wound and subsequently proliferate in necrotic tissue and secrete powerful toxins. These toxins destroy nearby tissue, generating gas at the same time. A gas composition of 5.9% hydrogen, 3.4% carbon dioxide, 74.5% nitrogen and 16.1% oxygen was reported in one clinical case.^[2]

Gas gangrene can cause necrosis, gas production, and sepsis. Progression to toxemia and shock is often very rapid.

Specific gangrenes

• Noma is a gangrene of the face.
• Necrotizing fasciitis affects the deeper layers of the skin.
• Fournier gangrene usually affects the male genitals.

Treatment

Treatment is usually surgical debridement, and excision with amputation is necessary in many cases. Antibiotics alone are not effective because they do not penetrate ischemic muscles sufficiently.

See also

• Wound healing
• Liquefactive necrosis
• Bedsore

References

1. ↑ chapter 3.html
2. ↑