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How is gangrene diagnosed?
A person should suspect gangrene if any local body area changes color (especially if it is red, blue, or black) and becomes numb or painful. If the symptoms include those stated above for either dry or wet gangrene, the individual should immediately seek medical help.
The diagnosis is usually based on the clinical symptoms of either wet or dry gangrene. Often other tests are done in cases of wet gangrene to further define the infecting agent(s), the type of gangrene, and the extent of the infection. For example, X-rays, CT, or mri studies are done to see how far gas or necrosis (or both) has progressed from the local site. These studies are often done to help determine the extent of gangrene in both limb and internal types of gangrene. Blood cultures as well as cultures of the infected tissue and exudates are usually done to determine the infective agent(s) and to determine appropriate antibiotic therapy.
For dry gangrene, vascular surgeons often do angiography (a radiologic study with dye that shows arterial blood flow in tissues, also termed arteriogram) to see the extent of ongoing or potential arterial blood loss to tissue.
How is gangrene treated?
Treatment of gangrene depends upon the type of gangrene (dry vs. wet), the subtype of wet gangrene, and upon how much tissue is compromised by the gangrene. Immediate treatment is needed in all cases of wet gangrene and in some cases of dry gangrene. Treatment for all cases of gangrene usually involves surgery, medical treatment, supportive care, and occasionally, rehabilitation.
Dry gangrene is usually treated with surgery that removes the dead tissue(s), such as a toe. How much tissue is removed may depend on how much arterial blood flow is still reaching other tissue(s). Often, the patient is treated with antibiotics to prevent infection of remaining viable tissue. The patient may also receive anticoagulants to reduce blood clotting. Supportive care can consist of surgical wound care and rehabilitation for reuse of the digits or limb. Some patients simply slough off the dry gangrenous tissue (termed autoamputation). This happens most often when medical and surgical caregivers are not readily available to the patient in remote areas or in some third world countries. Many patients, if they do not get infected, can recover from autoamputation.
Wet gangrene is a medical emergency and needs immediate treatment. Treatment is usually done in a hospital, and a surgeon needs to be involved because the local area needs debridement (surgical removal of the dead and dying tissue). In some patients, debridement will not be adequate therapy, and amputation of a limb may be needed. At the same time as surgical treatment, intravenous antibiotics (usually a combination of two or more antibiotics, one of which is effective in killing anaerobic bacteria like Clostridium perfringens and another antibiotic effective against methicillin-resistant Staphylococcus aureus or mrsa) need to be administered. Consultation with an infectious disease specialist and a surgeon is recommended. Internal gangrene requires an operation in the hospital to remove the gangrenous tissue. Some patients develop sepsis and require the support of an intensive-care unit in which supportive care for other life-threatening problems such as hypotension (low blood pressure) can be treated. Rehabilitation therapy for patients with amputation is highly recommended.
Some clinicians treat gangrene, especially wet gangrene, with hyperbaric oxygen (oxygen given under pressure with the patient inside a chamber). Since some studies indicate that hyperbaric oxygen treatment improves tissue oxygen supply and can inhibit or kill anaerobic bacteria, this therapy is used to treat patients with gangrene. However, it is not available in many hospitals and is used in conjunction with the above described therapeutic methods, not as a primary therapy for wet gangrene.