Gangrene Health Article

Definition

Gangrene is the death of tissue caused by the lack of blood supply.

Description

The severity of gangrene is wide-ranging. It can affect a minuscule skin area or a finger or toe, or even an entire limb such as an arm, a foot, or a leg. Gangrene is usually classified into two categories, dry gangrene and wet gangrene.

Dry gangrene

Some of the most common causes of dry gangrene include:

• arterial obstruction, or occlusion of an artery, caused by arteriosclerosis, diabetes mellitus, AIDS or blood clot
• severe blunt trauma to a part of the body causing damage and therefore obstruction of an artery

• frostbite, which occurs when tissue becomes so cold that it is literally deprived of blood and therefore oxygen, and dies
• diseases that affect the blood vessels, and especially the arteries, such as Buerger's disease or Raynaud's disease
• traumatic occurrences such as crushing injuries, fractures, burns, and even injections given into skin or muscle

Wet gangrene

Causative organisms for wet gangrene infection include:

• Streptococcus
• Staphylococcus

A serious but rare form of infection with Group A Streptococcus can impede blood flow and, if untreated, can progress to gangrene caused by chemical reaction. This type of gangrene is more commonly called necrotizing fasciitis, or infection of the skin and tissues directly beneath the skin.

Gas gangrene, the most serious form of wet gangrene, often is caused by Clostridium bacteria, which are normal inhabitants of the gastrointestinal, respiratory, and female genital tracts. They often infect thigh amputation wounds, especially in those individuals who have lost control of their bowel function (incontinence). Gangrene, incontinence, and debility are often combined in patients with diabetes, and it is in the amputation stumps of diabetic patients that gas gangrene often occurs.

Areas of either dry or moist gangrene are initially characterized by a red line on the skin that marks the border of the affected tissues. The onset of dry gangrene is normally characterized by dull, aching pain at the site. The skin usually develops an abnormal, unhealthyappearing pallor and is cold to the touch. As tissues begin to die, dry gangrene may continue to cause some pain; but it may go unnoticed, especially in the elderly or in those individuals with diminished sensation to the affected area. As more tissue dies, its color changes to brown, and finally purplish-black. This dead tissue will gradually separate from the healthy tissue and fall off.

Gas gangrene has a dramatically sudden, rapid onset. It is frequently first noticed as a marked swelling and either a pallid or brownish-red colored area surrounding the wound site. The borders of the infected site can expand literally within minutes. Symptoms of gas gangrene include:

• edema, or swelling, at the injury site that expands quickly
• pain in the area surrounding the skin injury
• crepitus, a bubbly, crackling sound often heard upon palpation
• pallor at the injury site, then increasingly dusky discoloration
• low-grade to moderate temperature elevation
• tachycardia, or increased heart rate
• diaphoresis, or clammy, sweaty skin
• formation of blisters filled with rust-colored fluid
• wound drainage, foul-smelling and rusty or bloody in appearance
• in severe cases, shock (Symptoms of shock include generalized pallor, hypotension, rapid pulse, and cold hands and feet.)