A century since the First World War, gangrene remains a problem, albeit a less deadly problem, for many people. A significant number of soldiers in WWI and in the Second World War acquired the most serious, infectious form of gangrene, with half of those infected with this, now relatively rare skin and soft tissue disease dying because of it.1
The distinctive smell of that "gas gangrene" was the only means to diagnose the condition in the trenches and on the battlefield. This olfactory technique was described as far back as the first half of the last millennium, in medieval times.1
Use this page to learn about the modern-day factors that lead to different forms of gangrene, and how doctors today manage the conditions.
Contents of this article:
Fast facts on gangrene
Here are some key points about gangrene. More detail and supporting information is in the body of this article.
- Gangrene is a serious, sometimes life-threatening condition in which the skin, muscle and other tissues die as a result of lost blood supply.
- It is usually external, affecting the extremities, but it can also affect internal tissues.
- Gangrene is most commonly associated with chronic illness, such as a severe complication of diabetes, or acute causes, such as certain types of injury.
- Dry gangrene is caused by chronic illness, while wet gangrene - including gas gangrene - is usually an acute form involving bacterial infection and caused by injury, for example.
- Wet gangrene can result from chronic disease if the dry gangrene becomes infected.
- Surgical complication can lead to internal gangrene, which presents with signs of toxic shock.
- Initial diagnosis is made based on the history leading up to the presentation, and a physical examination, including external appearance and smell. Follow-up laboratory and imaging tests, and sometimes exploratory surgery may also be used to diagnose gangrene.
- Urgent treatment is important to prevent further serious illness and death, and includes removal of dead tissue or even amputation.
- Prevention of gangrene is an important part of living with certain chronic illnesses, including diabetes. Doctors working in hospitals, especially those involved in abdominal surgery, also take steps to prevent gangrene.
What is gangrene?
Gangrene is a disease of the skin and soft tissues - and sometimes internal tissues and organs - that results in tissue death (necrosis). It comes in two broad forms:2-5
Crushing or penetrating wounds sustained in dirty conditions can lead to gangrene. Half of all soldiers affected by gangrene in the World Wars did not survive.
- Dry gangrene - sometimes called mummification, this is the slow-onset form most commonly associated with chronic disease, including diabetes
- Wet gangrene - also known as moist gangrene, this is the sudden onset (acute) form.
Gas gangrene (also called clostridial myonecrosis) is a particularly virulent form of wet gangrene.2,3,6,7 This is the condition that is associated with poorly cleansed wounds of the kind suffered in war - deep crushing or penetrating wounds that become infected with bacteria, Clostridium in particular. In addition to injury, the condition can result from surgery.
Dry forms, which are the result of a progressive loss of blood supply to tissues, can become wet forms if they also develop a bacterial infection.5
What causes gangrene?
All forms of gangrene result from the loss of blood supply to tissue - often at the extremities - which deprives tissue of oxygen and nutrients, causing the tissue to die (necrosis).2,5
Mortification is a type of gangrene where a portion of tissue dies all at once, whereas ulceration involves death at a molecular or cellular level.5
The reasons behind necrosis and tissue death differ depending on the specific type of gangrene. Broadly:5
- In dry gangrene, the necrosis is caused by slow, progressive loss of blood supply (perfusion)
- Wet gangrene results from a sudden loss of perfusion, and is worsened by the involvement of bacteria.
Diabetes and blood vessel diseases such as atherosclerosis are the most common causes of dry gangrene.4
Dry gangrene is more likely to occur in older people with diabetic foot - a common complication of undiagnosed or uncontrolled diabetes. In such cases, the circulation of blood to the feet worsens, and there is a higher likelihood of any foot wounds going unnoticed by the patient. This is because of diabetic neuropathy, which is a loss of sensation resulting from nerve damage caused by diabetes.
Complications of diabetes affecting the extremities, especially the feet, are a risk factor for gangrene, partly because painless wounds can go unnoticed.
Further causes of gangrene include:5
- "Senile gangrene" caused by "aged" blood vessels, and therefore, usually affecting older people. This can also occur in younger people with arteriosclerosis (arterial narrowing) caused by, for example, a combination of syphilis and alcohol dependency.
- Surgery - an operation involving the ligation of an artery, as treatment of an aneurysm for example, can shut off blood supply in such a way as to cause gangrene. This form is usually dry but can also become wet gangrene.
- Mechanical constriction - for example, gangrene can be revealed when pressure splints are removed. Trauma/injury can also cause mechanical constriction.
- Severe burns, scalds and cold - heat, chemical agents (especially carbolic acid, but also caustic potash, and nitric or sulphuric acid), and cold (including frostbite) can all lead to dry gangrene. If treatment involves wet or oily dressings and there are septic conditions, wet gangrene can develop.
- Raynaud's disease - this condition, in which spasm of blood vessels causes impaired circulation to the ends of fingers and toes, especially in cold weather, is implicated in some cases of gangrene.
- Angiosclerosis and intermittent claudication can be associated with gangrene.
- Eating large quantities of coarse rye bread - long-term intake of ergot, a fungus that can infect rye is implicated in gangrene development as ergotism involves vasoconstriction.
- Injury - deep, crushing or penetrating wounds that are sustained in conditions that allow bacterial infection to take hold can lead to gangrene. Such conditions are often seen in war zones, as well as in railway, machinery, and street accidents if lacerated and bruised tissues are contaminated with soil/dirt.
- Mechanical constriction - rarely, blood flow restriction caused by pressure from bandages, bone fractures, tumors, and so on, can lead to gangrene.
- Embolic gangrene - the sudden occlusion of an artery due to an embolism can lead to dry gangrene, but this can also increase the risk of infection and thus lead to wet gangrene.
- Any case of dry gangrene can progress to wet gangrene if there is an opportunity for bacterial infection.
Risk factors for gangrene, the first three of which are also culprits in blood vessel disease and diabetes, include:3,4
- Excessive alcohol intake
- Impaired immune function - as a result of, for example, HIV infection, chemotherapy, and radiation therapy
- Intravenous drug use
- Rarely, the anticoagulant drug warfarin, especially if used in combination with heparin.
Signs and symptoms of gangrene
The telltale features of gangrene are:2-4,6,7
- Loss of color in the affected body part - initially discolored but eventually turning dry and dark, going through red to black color in dry gangrene, or being swollen and foul-smelling in wet gangrene (and, in gas gangrene, producing particularly foul-smelling, brownish pus)
- Shiny appearance to the skin; shedding of skin; a clear line forming between affected and healthy skin
- Pain that is later followed by loss of sensation and an inability to move the part
- Loss of pulse in arteries.
If the gangrene is internal, there may not be any external signs, but the following may occur, as a result of septic shock and other complications:3,4
- Fever and chills
- Nausea, vomiting, and diarrhea
- Low blood pressure leading to light-headedness and fainting
- Shortness of breath and high heart rate.
In addition to the features seen in more common types of gangrene, there are certain signs and symptoms peculiar to gas gangrene, a less common form of wet gangrene. In gas gangrene the infected area of skin can quickly extend, with some changes visible in just a matter of minutes.
In cases of gas gangrene, the skin may:2-4,7,8
- Be very painfully swollen
- Be pale at first, but become red or bronze before finally turning blackish green
- • When palpated, create a crackling sensation (crepitus) due to the movement of gas under the skin (subcutaneous emphysema). The gas is produced by the bacteria causing infection and is highly toxic, causing the necrosis to spread quickly
- Show blisters filled with brown-red fluid
- Produce a foul-smelling brown-red or bloody fluid when the tissue affected tissue is drained or leaks (a serosanguineous discharge).
Certain muscles are more likely to be affected by gas gangrene. These include the muscles at the sides of the trunk, under the arms, and in the buttocks, thighs and calves.8
Diagnosis and tests for gangrene
Initial suspicion of gangrene calls for physical examination by a doctor, who will also take medical history, asking questions about symptoms and potential exposure to infection or trauma. During the examination the doctor will look for external signs and symptoms, as well as signs of shock.3,4,6,7
If gangrene is suspected, further diagnostic tests will be used to determine the type and extent of the necrosis, and to detect or rule out gas gangrene. These tests can include:7
- X-ray - to reveal gas bubbles in muscle tissue
- MRI and CT - to determine the extent of muscle involvement
- Olfactory tests - to detect the unique, foul smell that can indicate gangrene, especially gas gangrene.
As mentioned in the introduction at the top of this article, a unique, foul smell also alerts physicians to gangrene, especially gas gangrene.1
Tests that may be ordered to identify any bacterial infection - confirmed by white blood cell counts, Gram staining and sample culture - include:3,4,6,7
- Blood tests
- Laboratory examination of samples of the tissue affected and any discharge.
Surgery may be necessary to explore the extent of the necrosis and to gain tissue samples. Operations can also form part of the treatment of gangrene.4,7
Treatment and prevention of gangrene
To reduce the risk of serious complication and death, gangrene requires emergency treatment. As such, it is important that anyone with suspected symptoms of gangrene seeks immediate medical attention.
The most severe form, gas gangrene, is fatal without treatment. With treatment, there is a success rate of up to 60%7 (an improvement on the 50% rate achieved on battlefields for the soldiers serving in the World Wars1).
In all cases of dry gangrene caused by chronic disease, prevention is far better than cure - simply because cure is not possible after, for example, diabetic gangrene has set in, when amputation of an extremity becomes necessary.5 The same attention to prevention is also important in avoiding the acute risks of gangrene, such as from injury or extreme cold.
When gangrene is diagnosed, the particular treatment is dependent on the specific type, location and extent of diseased tissue, but may involve the following emergency measures:3,4,7
- Antibiotics administered directly into the bloodstream (intravenously)
- • Reconstructive surgery, involving skin grafting and other techniques, may be possible
- Amputation of an extremity, and even a whole limb, to halt the wider spread of gangrene.
Hyperbaric oxygen therapy
Hyperbaric oxygen therapy6,9-11 is used in other tissue infections and, in particular, diabetic foot ulcers that have become infected and failed to heal. It has been shown to reduce the need for amputation in cases of diabetic gangrene.
The idea behind this treatment is that a hyperbaric chamber of high-pressure oxygen creates a bactericidal and bacteriostatic effect and improves oxygen supply to the wounds by encouraging the formation of new blood vessels (angiogenesis), and causing greater dissolution of oxygen in plasma. However, the precise mechanism behind the effects of hyperbaric oxygen therapy remains unknown.
- Involves inhaling pure oxygen at the pressure of 2-3 absolute atmospheres (or 2-3 times 14.7 pounds per square inch)
- Takes place in single- or multi-patient pressure chambers
- Usually lasts 90 minutes, but ranges between 70 and 120 minutes
- Is typically administered over 20 or more sessions.
In certain settings, such as hospitals, healthcare professionals should practise measures that minimise the risk of infections such as gas gangrene. Such measures include:7
Frostbite can lead to gangrene, as can Reynaud's, a disease that usually affects the finger tips and tends to be worse in winter.
- Removing foreign bodies and dead tissue from wounds (debriding)
- Keeping wounds from trauma or surgery thoroughly clean
- Routinely administering, for abdominal surgery, intravenous antibiotics - before, during, and after the operation.
People with risk factors for gangrene can also take measures to protect themselves:7
- Watch out for nerve-damage complications of diabetes, especially in the feet
- look for cuts, sores, redness, swelling or discharge on the feet and hands every day, and have a medical check of foot health once a year
- Control body weight
- to prevent diabetes, arterial disease, and poor wound healing
- Stop smoking
- Prevent infection
- by washing wounds with a mild soap and water and keeping them clean and dry
- Look out for signs of frostbite if exposed to prolonged cold
- seek urgent medical attention if the skin becomes pale, hard, cold and numb.