Gangrene essentially means death of tissues due to lack of blood supply and invasion of deeper tissues with infection.
Gangrene may be broadly classified into two types – dry and wet gangrene.
There are several other types of gangrene that are rarer. However, all types of gangrene manifest either as dry or wet form.
In this type of gangrene there is obstruction or slowing of blood flow into the organ or part of the body that is affected. Peripheral parts like toes, fingers, tip of the nose, earlobes etc. are commonly involved.
Dry gangrene is usually seen in patients of type 1 and type 2 diabetes. In both types of diabetes long term high blood sugar damages the small arteries and blood vessels that supply the end parts of the body like fingers and toes. This leads to obstruction and slowing of blood flow and ultimately gangrene.
In patients with high cholesterol, or dyslipidemia, there is a risk of deposition of cholesterol and lipids called plaques within the blood vessels. In the peripheries like toes and fingers this leads to decrease in the blood vessel diameters by narrowing of the lumen. This may lead to formation of gangrene.
Patients with peripheral arterial disease develop fatty acid deposits or develop narrowing of peripheral blood vessels. Some conditions include Raynaud’s disease and Scleroderma. This restricts blood supply to hand or leg muscles and may cause gangrene.
Dry gangrene is usually characterized by cold, painless and dry and shrivelled up affected part. There is surrounding healthy skin. The area affected is said to appear mummified.
Wet gangrene occurs when infection and bacteria invade deeper tissues after injuries, frost bites, foot ulcers or burns. There is excessive swelling of the affected part due to release of the toxins from the invading bacteria.
This leads to blockage of the blood supply and worsening of the infection as the fighter cells of the body (white blood cells) cannot reach the area affected via blood vessels.
Wet gangrene can spread much quicker than dry gangrene and may lead to life-threatening complications like septic shock if not treated immediately.
Wet gangrene appears discoloured or black usually with acute and excruciating pain. There are black blisters and foul-smelling pus beneath the thinned skin at the area.