Gangrene, Causes, Signs and Symptoms, Diagnosis and Treatment.

Gangrene is a type of tissue death caused by a lack of blood supply.[4] Symptoms may include a change in skin color to red or black, numbness, swelling, pain, skin breakdown, and coolness.[1] The feet and hands are most commonly affected.[1] If the gangrene is caused by an infectious agent it may present with a fever or sepsis.[1]

Risk factors include diabetes, peripheral arterial disease, smoking, major trauma, alcoholism, HIV/AIDS, frostbite, influenza, dengue fever, malaria, chickenpox, plague, hypernatremia, radiation injuries, meningococcal disease, Group B streptococcal infection and Raynaud's syndrome.[3][4] It can be classified as dry gangrene, wet gangrene, gas gangrene, internal gangrene, and necrotizing fasciitis.[3] The diagnosis of gangrene is based on symptoms and supported by tests such as medical imaging.[6]

Treatment may involve surgery to remove the dead tissue, antibiotics to treat any infection, and efforts to address the underlying cause.[5] Surgical efforts may include debridement, amputation, or the use of maggot therapy.[5] Efforts to treat the underlying cause may include bypass surgery or angioplasty.[5] In certain cases, hyperbaric oxygen therapy may be useful.[5] How commonly the condition occurs is unknown.[2] Symptoms may include a change in skin color to red or black, numbness, pain, skin breakdown, and coolness.[1] The feet and hands are most commonly involved.[1]Gangrene is caused by a critically insufficient blood supply (e.g., peripheral vascular disease) or infection.[3][7][8] It is associated with diabetes[9] and long-term tobacco smoking.[4][3]
Dry gangrene

Dry gangrene is a form of coagulative necrosis that develops in ischemic tissue, where the blood supply is inadequate to keep tissue viable. It is not a disease itself, but a symptom of other diseases.[10] The term dry is used only when referring to a limb or to the gut (in other locations, this same type of necrosis is called an infarction, such as myocardial infarction).[11] Dry gangrene is often due to peripheral artery disease, but can be due to acute limb ischemia. As a result, people with arteriosclerosis, high cholesterol, diabetes and smokers commonly have dry gangrene.[12] The limited oxygen in the ischemic limb limits putrefaction and bacteria fail to survive. The affected part is dry, shrunken, and dark reddish-black. The line of separation usually brings about complete separation, with eventual falling off of the gangrenous tissue if it is not removed surgically, a process called autoamputation.[12]

Dry gangrene is the result of chronic ischemia without infection. If ischemia is detected early, when ischemic wounds rather than gangrene are present, the process can be treated by revascularization (via vascular bypass or angioplasty).[13] However, once gangrene has developed, the affected tissues are not salvageable.[14] Because dry gangrene is not accompanied by infection, it is not as emergent as gas gangrene or wet gangrene, both of which have a risk of sepsis. Over time, dry gangrene may develop into wet gangrene if an infection develops in the dead tissues.[15]