Gangrene

There are many types of gangrene. They are distinguished by the presence or absence of bacteria, and the depth of spread of infection. Some of the types are:

1. Dry gangrene: This is caused gradually when the blood supply to an area is disrupted or cut off. Dry gangrene occurs most commonly in the extremities and does not include a bacterial infection. Atherosclerosis and diabetes are usually the underlying causes. Initially the skin turns brown and then turns green-ish black.
2. Wet gangrene: Wet gangrene occurs after a deep injury gets a bacterial infection. In this case, the skin will blister, swell up and look like it has a fluidic consistency. Wet gangrene needs medical attention since it can turn deadly if the infection spreads. 
3. Gas gangrene: Gas gangrene affects deeper tissue which means that the skin will initially look normal. It is caused by a specific bacterium called Clostridium perfringens usually after a deep wound. The bacterium releases gas which is where the name comes from. Eventually the skin will develop a darker colour, and there may be a ‘crackling’ sound when it is touched caused by the gas bubbles. This is a life-threatening situation and requires prompt medical care. 
4. Internal gangrene: This involves gangrene that directly infects an internal organ. This can happen if blood flow is disrupted, as it can be if there is a hernia. There is severe pain and fever as well, and medical attention is required.
5. Necrotising fasciitis: Also known as flesh eating bacteria, this is a rare but often lethal infection. It is caused by different types of bacteria that can penetrate the skin on injury and cause severe, widespread infection and septic shock. There is intense pain at the site of injury, swelling and redness. Following this there is high fever and diarrhoea as well. While anyone can get necrotising fasciitis, it is more common in older people and those with a poor immune system. 
6. Fournier’s gangrene: Fournier’s gangrene affects the genitalia and is usually caused by Sexually Transmitted Infections (STIs) or Urinary Tract Infections (UTIs). There is swelling and pain in the genitals and needs to be treated promptly.

Symptoms will depend on the type and severity of the gangrene. They will be more severe and widespread if a bacterial infection is involved. Initially the symptoms are:

• Redness, swelling in the area
• Formation of blisters in the area
• Loss of sensation in the area or severe pain
• Cold and pale skin

If there is an infection in the area, there will be a foul smelling discharge as well. As the gangrene progresses, more symptoms will appear:

• The skin becomes brown and eventually purplish-black, which means that the tissue is dying 
• High fever and chills
• Dizziness
• Rapid, shallow breathing 

The affected skin may develop a watery consistency and there may be a crackling sound on touching it. In the worst case scenario, the infection will progress to septic shock which involves multi-organ infection. Septic shock is life-threatening and requires immediate care. It is hard to spot but some signs include: 

1. A low temperature 
2. Shallow breathing 
3. Altered mental state
4. Fatigue 
5. Diarrhoea 
6. Intense pain or swelling at the site of a wound 

Generally speaking, if a wound is taking longer to heal than usual and there is discolouration, seek medical help.

Gangrene is caused by the interruption of blood flow to an area. This can develop over time because of compromised blood vessels and is often precipitated by serious injuries. Such injuries can lead to massive blood loss and an infection can be introduced at the site.

Similar complications can occur when surgery is involved; unsterile equipment that penetrates deep into tissue can cause a bacterial infection. Note that this is a rare occurrence now that higher standards of safety and cleanliness are followed during surgery.

Frostbite can also lead to gangrene in the extremities since the extreme cold cuts off blood supply. There is a similar risk following burn injuries. 

Internal gangrene, which involves the organs, can be caused by a disruption of blood flow to the organ caused by a protrusion such as a hernia. In Fournier’s gangrene, which involves the genitalia, a UTI (Urinary Tract Infection) or STI (Sexually Transmitted Infection) can lead to gangrene as well. 

As can be inferred, there are many proximate causes of gangrene since tissue will start dying if blood supply is disrupted over a period of time. 

There are many underlying conditions that can eventually lead to gangrene as well. They mostly include those affecting the blood vessels, diseases and conditions that lower immunity and lifestyle issues as well.

Blood vessel diseases:

1. Diabetes: The blood vessels can get damaged due to chronic hyperglycemia (high blood sugar) and blood flow to the extremities can be disrupted. In fact, it is recommended that diabetics get annual exams of their feet to test for sensation and status of blood flow. High blood sugar can lead to nerve damage as well, which means that people can injure their feet and not realise it, thus making it more likely for infections to fester.
2. Atherosclerosis: The arteries become clogged and damaged due to deposits of fats and cholesterol, causing blood flow to be disrupted. 
3. Raynaud’s disease: Raynaud’s is a disease in which blood vessels in the extremities react abnormally to cold temperatures and disrupt blood flow. 
4. Peripheral artery disease: In this disease, blood vessels in the limbs are narrowed due to fatty deposits. 
5. Obesity: Obesity is linked to diabetes and other blood vessel disorders. The added strain on the body also leads to reduced blood flow which increases the likelihood of gangrene. 

Weakened Immunity:

1. Those who have been treated with radiation or chemotherapy in the past are at a higher risk. 
2. Those who are over 60 are at higher risk since the immune system is less robust. 
3. Those with HIV are at a higher risk. 
4. Those with kidney failure are at a higher risk. 
5. Those suffering from malnutrition are also at higher risk.

Lifestyle 

1. Certain medication and injectable drugs can lead to gangrene. 
2. Smoking
3. Long-term alcohol abuse

While all these factors increase the likelihood of gangrene, healthy people with no underlying conditions can sometimes develop it as well. 

Since there are many chronic, underlying health issues that can increase the likelihood of gangrene, and managing these can improve your overall health and strengthen your immunity, thus lowering the risk of this condition.

Many blood vessel diseases, such as atherosclerosis can be improved by following a balanced diet and delivers all essential nutrients in their required amount. This means cutting down on foods with large amounts of artificial sugars, unhealthy fats and carbohydrates. It is also important to incorporate exercise into your daily routine. Start with exercises that are easy and sustainable on a daily basis. 

At the same time, habits such as drinking alcohol regularly or smoking can increase the likelihood of developing gangrene. 

For diabetic patients, it is important to get at least yearly foot examinations. As explained above, there may be a loss of sensation in the feet meaning that cuts are not as easily noticed, making infections more likely. It is advised to not walk barefoot outside and to wear shoes that are soft. 

The proximate cause of gangrene is often an injury. If the injury is not promptly cleaned with disinfectant, there is a chance of infection. Therefore, it is always important to sanitise after an injury; doing so will greatly reduce the chances of getting gangrene.

Your doctor will conduct a thorough physical examination to look for obvious signs of gangrene, such as a discolouration, or foul smelling discharge. The doctor will also conduct a medical history check and ask about chronic conditions that can increase the likelihood of gangrene. You may also be asked about recent injuries or surgeries. 

A series of blood testing, imaging tests and even surgery may be required to determine the extent and type of gangrene. Some standard tests include: 

1. Blood tests primarily to determine if the amount of white blood cells is high, indicating that there is an infection.
2. Blood/ tissue culture. A sample of blood or infected tissue will be taken and cultured to detect what type of bacteria is responsible for the infection, and to prescribe appropriate antibiotics.
3. Imaging tests such as X-rays or CT scans may be needed if it is suspected that the infection is in deeper tissue and has spread. 
4. Surgery may be required sometimes if imaging diagnostics are inconclusive and the infection is suspected to have spread. 

Treatment will depend on the extent and type of gangrene presented. Common treatments include: 

• Surgery: Dead tissue is removed since it cannot heal and to prevent the gangrene from spreading. This will allow surrounding tissue to gradually heal as well.
• Surgeries to restore blood flow such as angioplasty or bypass of the affected vessels may be required if the blockage is severe. Restoring blood flow will reduce the likelihood of getting gangrene again. 
• Reconstructive surgery: A skin graft may be performed to replace dead skin removed from the affected area. To perform a graft, skin from a healthy area is taken and stitched over the infected area. This is only done if blood flow has been restored in the region. Grafts are usually done to cover the area damaged by gangrene.
• Larval debridement therapy: This is an unconventional method wherein clean, lab grown maggots are put in the site of the open wound. The maggots eat the dead tissue and release chemicals that kill harmful bacteria as well. They are removed after a couple of days following which the skin may be grafted or treated with antibiotics.
• Amputation: Unfortunately, there are times when gangrene is too widespread and the affected limb has to be amputated to prevent further spread. This can happen if treatment is left too late. 
• Antibiotic treatment will be required if the gangrene is caused by infection. This can be done either using pills or injections may be required if the infection is more widespread. Blood transfusions may also be required.
• Hyperbaric oxygen therapy: In this therapy, you will be placed in a chamber that is pressurized with oxygen. The pressure will be increased gradually until it is around 2.5 times that of atmospheric pressure. This will allow your blood to carry more oxygen and aid in the healing process of the tissue surrounding the damaged site. 

Generally, dry gangrene has a good prognosis if it is treated in time and there is minimal damage. In wet gangrene, prognosis is dependent on the extent on the infection and how soon treatment is begun.