Discover

'Gangrene' is necrosis and subsequent decay of body tissues caused by infection or thrombosis or lack of blood flow. It is usually the result of critically insufficient blood supply sometimes caused by injury and subsequent contamination with bacteria. This condition is most common in the extremities. The best of all possible treatments is revascularization (restoration of blood flow) of the affected organ, which can reverse some of the effects of necrosis and allow healing. Depending on the extent of tissue loss and location, treatment other than revascularization runs the gamut from allowing digits to auto-amputate (fall off), debridement and local care, to amputation, the removal of infected necrotic tissues.

Contents

History

Types of gangrene

Dry gangrene

Internal gangrene

Wet gangrene

Gas gangrene

Specific gangrenes

Treatment

Etymology

See also

History

In the years before antibiotics, and as early as the year 1028, fly maggots were commonly used to treat chronic wounds or ulcers to prevent or stop necrotic spread. Some species of maggots consume only dead flesh, leaving nearby living tissue unaffected. Their use largely died out after the introduction of antibiotics and enzyme treatments for wounds. In recent years, however, maggot therapy has regained some credibility and is sometimes employed to great effect in cases of chronic tissue necrosis.

Types of gangrene

Dry gangrene

Dry Gangrene begins at the distal part of the limb due to ischaemia. A typical example of dry gangrene is the toes and feet of an old patient due to arteriosclerosis. Gangrene spreads slowly upwards until it reaches the point where the blood supply is adequate to keep the tissue viable. Macroscopically, the affected part is dry, shrunken and dark black, resembling the foot of a mummy. It is black due to liberation of hemoglobin from hemolysed red blood cell which is acted upon by the hydrogendisulfide(HG) produced by the bacterias resulting in formation of black iron sulfide. The line of separation usually brings about complete separation with eventual falling off of the gangrenous tissue if it is not removed surgically.
If the blood flow is interrupted for a reason other than severe bacterial infection, the result is a dry gangrene. Persons with impaired peripheral blood flow, such as diabetics, are at greater risk of dry gangrene.
The early signs of dry gangrene are a dull ache and sensation of coldness in the 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.

Internal gangrene

In this gangrene the tissues become white. It is located inside the body, usually after surgery or trauma. Also called "white gangrene".

Wet gangrene

Wet Gangrene Occurs in naturally moist tissue and organs such as the mouth, bowel, lung, cervix vulva, etc. Diabetic foot is another example of wet gangrene due to high sugar content in the necrosed tissue which favour the growth of bacteria. Bedsores occurring in a bed-ridden patient due to pressure sites like the sacrum, buttocks and heels are the other important clinical condition included in wet gangrene. In wet gangrene, the tissue is affected by saprogenic microorganisms (Bac.perfringes, fusiformis, putrificans, etc), becomes swollen and emits fetid smell. It develops in the tissue rich in water: Lungs, Intestine, noma(water cancer) gangrene of cheeks in children at measles. Wet gangrene usually develops rapidly due to blockage of venous and/or arterial blood flow. The affected part is stuffed with blood which favour the rapid growth of bacteria. The toxic products formed by bacteria are absorbed causing systemic manifestation of septicemia and finally death. Macroscopically the effected part is swollen edematpus, soft, putrid, rotten, dark. The part is dark due to the same mechanism as in dry gangrene.

Gas gangrene

Main articles: Gas gangrene

Gas gangrene is a bacterial infection that produces gas within tissues in gangrene. It is a deadly form of gangrene usually caused by ''Clostridium perfringens'' bacteria. Due to its tendency to progress rapidly, it is considered a medical emergency. The rapid progression of gas gangrene occurs because of the tendency of expanding gas to open and separate the internal tissues, progressively exposing more and more healthy tissue to infection.
Gas gangrene is caused by exotoxin-producing clostridial species, which is mostly found in soil, and other anaerobes (e.g. ''Bacteroides'' and anaerobic streptococci). These environmental bacteria may enter the muscle through a wound and go on to 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.
Gas gangrene can cause myonecrosis, gas production, and sepsis. Progression to toxemia and shock is often very rapid.

Specific gangrenes

★ Noma is a gangrene of the face.

★ Necrotizing fasciitis is attacking the deeper layers of the skin.

★ Fournier gangrene usually affects the male genitals.

Treatment

Treatment is usually surgical debridement and excision with amputation necessary in many cases. Antibiotics alone are not effective because they do not penetrate ischemic muscles sufficiently. However, penicillin is given as an adjuvant treatment to surgery. In addition to surgery and antibiotics, Hyperbaric oxygen therapy (HBOT) is used and acts to inhibit the growth of and kill the anaerobic ''C. perfringens''.

Etymology

It comes from the Latin word "gangraena" and from the Greek gangraina (γάγγραινα), which means "putrefaction of tissues".

See also

★ Wound healing

★ Liquefactive necrosis

★ Bedsore