Diabetes & The Body

Gangrene

Gangrene is defined as the gradual destruction of living tissue, due to an obstruction in the supply of blood and oxygen to an area of the body. Any part of the body can be affected by gangrene, but it most frequently occurs in the hands, fingers, feet and toes, particularly as these acral parts of the body seem to be the most susceptible to trauma. Gangrene of the skin is often called sphaceloderma. This is caused by infection, vascular disease, trauma, frostbite and diabetes.

Gangrene can also occur internally and is extremely dangerous if abdominal organs are involved. It does not generally discriminate between the sexes, although a predisposition to malnourished, elderly persons or those with Diabetes mellitus or serious vascular impairment is recognised.

Diabetic gangrene results from three factors:

• Trophic changes, caused by peripheral neuritis
• Ischaemia, caused by atheroma in the arteries
• Lowered resistance to infection, caused by excess sugar in the tissues

Types of Gangrene

Basically, gangrene is of two types

• Dry gangrene and
• Wet gangrene

Dry gangrene arises due to loss of arterial blood supply to the tissue or part whereas, wet gangrene arise due to both the artery as well vein being blocked. This condition is often confused with a dry gangrene with superadded infection.

There is a third type of gangrene that is considered as a wet gangrene by some and is called Gas Gangrene. This occurs mostly after accidents and in contaminated wounds. Here the superadded infection is due to spore forming Clostridia and is a highly contagious infection.

What Causes It?

Although the list of contributing factors causing each type of gangrene is theoretically almost unlimited, some of the documented causes have been detailed. Arteriosclerosis obliterans and thromboangitis obliterans account for 95% of all cases of pvd causing damage.

Additional causes of gangrene:

• Raynards disease or syndrome
• Vascular changes with diabetes mellitus
• Sickle cell anaemia
• Arterial or venous embolism
• Severe trauma
• Chemical injury
• Cryoglobulinemia and pyoderma gangrenosum
• Dermatitis nodularis necrotica,
• Subacute bacterial endocarditis
• Collagen disease
• Leprosy
• Tuberculosis
• Erysipelas and surgical infections of the palms

Gangrene of the fingertips may also complicate meningitis, malaria, typhus fever, typhoid fever, diptheria and pneumonia. Anthrax or malignant pustule, which is characterized by a carbuncle or papule with black centre surrounded by a halo of vesicles and inflammation, may result in gangrene of the hand. Ulceration of the fingertips has been reported following MI”.

Smoking and excessive alcohol consumption have also been recognised as specific risk factors because of the possibility of arteriosclerosis and interference to the function of the blood vessels respectively.

Diagnosis

Dry gangrene can be diagnosed by good medical history and thorough examination, tissue or blood cultures from affected site.

Diagnosis of wet gangrene can be done by good medical history and thorough examination, blood and tissue cultures of the area affected, and by X-rays.

Where as gas gangrene can be diagnosed usually by the presenting clinical features and by affirming a recent history of trauma or surgery. Cultures from the wound confirm the diagnosis by recording findings of C. perfringens, with a presentation of gram positive bacillus bacteria. X-rays of the area show black spots within the tissue, synonymous with gas bubbles. Blood tests may reveal leukocytosis and hemolysis in later stages.

Treatment

As dry gangrene is rarely life threatening, regular monitoring of the progression of the disease is often all that is required. Eventually the area of dead tissue becomes autolytic and healing takes place at the demarcation line between the dead and living tissue. In its early stages however, extreme pain and a high fever are often present and the administering of analgesics may be required.

Wet gangrene is usually curable in the early stages with antibiotic therapy and excision of dead tissue. The use of Hyperbaric Oxygen (H₂O₂) Therapy is also stated in the treatment of vascular diseases. This treatment is used to infuse oxygen back into depleted tissues and prevent the proliferation of anaerobic bacteria.

For gas gangrene debridement of necrotic tissue is carried out prior to the administering of high doses of intravenous penicillin. If signs of myositis or cellulitis appear, then a wide surgical excision of the affected area is carried out. If available, hyperbaric treatment should then be commenced.

Prognosis

The prognosis for dry gangrene is very good in the absence of infection. If bacteria invade the necrotic tissue however, then systemic antibiotic therapy will be required as deeper tissues are likely to become infected.

For wet gangrene, the spread of infection is very fast and death may occur unless the condition can be prevented from becoming systemic.

In severe cases, where treatment has not been administered in time, delirium, coma and circulatory shutdown usually precede death for those with gas gangrene. Wide debridement of the area and possible amputation usually precipitate a successful recovery where the disease has been diagnosed in its early stages.