- 1 Gangrene and its History
- 2 What is Gangrene?
- 3 Gangrene: Who’s At Risk?
- 4 Pathogenesis of Gangrene
- 5 The Types of Gangrene and Their Symptoms
- 6 How Can Gangrene Be Diagnosed?
- 7 Treatment Modalities in Managing Gangrene
Gangrene and its History
Originating from the Latin and Greek terms gangreana and gangraina, gangrene literally means degradation of a part of the living body. In the 16th century, the term was frequently utilized by surgeons, particularly in treating diseases of external pathological circumstances. A century after, the term was used in a more specific pathological meaning. [1,2]
Since the old times, there had been two instances of widespread gangrene scourges. Once was at the Victorian era, when the infirmaries were swarmed with gangrene cases. The other was during World War I, when gangrenes were amongst severed war soldiers and were described as lethal emphysematous wounds with bubbly, foul smelling, brownish discharges. 
An image depicting gangrene as death of the tissue of the body.
What is Gangrene?
Gangrene is a term used to describe death of tissues with subsequent decay. This can be brought about by lack of blood supply, triggering necrosis and tissue death. It can involve any part of the body, though it mostly is present in distal parts of the extremities. [3, 4, 5]
Distal extremity gangrene, one of the most common examples of gangrene.
Gangrene: Who’s At Risk?
In general, certain groups of people are at increased risks for gangrene. These included those with the following: [2,3]
At the age of 60 years, immune systems tend to be less competent. Thus, infections may be more frequent and there will be higher risks for gangrenes.
History of smoking
Smoking increases the risk for atherosclerosis, narrowing the arteries and interrupting normal blood circulation.
High blood glucose levels
Increased levels of blood sugar can damage blood vessels, impeding blood circulation and thus, cause gangrene.
Decreased level of immune system
Having a weakened immune system increases one’s risk of infection. Such an infection may worsen and complicate, eventually lead to gangrene. People with decreased levels of immune systems include those who have had chemotherapies and radiotherapies, with HIV, malnourished, intravenous drug users, obese, patients with renal failure, and with chronic consumption of alcohol.
Injuries or have undergone surgical procedures
Injuries may cause an abrupt loss of blood flow to an area of the body. This induces infection, and lead to gangrene.
Vascular illnesses such as atherosclerosis
Fats can deposit within arteries as plaques and consequently, narrow them, thereby restricting the supply of blood and potentially giving rise to gangrenes.
Pathogenesis of Gangrene
The generation of gangrene may usually root from either infection or ischemia. These mechanisms may differ in their means, but generally end up in one similar outcome: gangrene. 
Gangrene from Ischemia
Peripheral arterial diseases induce narrowing of blood vessels. Consequently, blood circulation and supply to distal extremities are compromised. Atheromatous plaques consist of a core of necrosis and a cap for protection. Blood flow impingement can destroy the said cap, causing thrombogenesis and further diminish blood supply. Critical ischemia of tissues is mainly composed of persistent wounds, necrotic tissues and pain upon rest. A large thrombus can even occlude important structures for blood circulation and cause gangrene.
Gangrene from Infection
Contamination of wounds by Clostridium spores induces infection. Presence of tissue necrosis further triggers multiplication of Clostridium spores. Local spread of muscle and fat necrosis, along with blood vessel thrombosis then ensue. This processes, along with tissue edema, further compromise circulation, thus inducing gangrene.
The Types of Gangrene and Their Symptoms
This type of gangrene is an example of coagulation necrosis. It is mainly due to diminished arterial blood supply, most commonly rooting from poor circulation or obstruction. Usually a slow and gradual process, it ultimately affects the peripheral extremities. [ 7, 8, 9]
It is characterized by dry and withered skin, usually brownish to purplish in hue. The affected tissue eventually becomes cold and black in color, due to the black iron sulfide produced by hemolyzed hemoglobin remained among the tissues. Its mummified tissue then dries up and finally sloughs off and autoamputates. [5, 8, 10, 11]
This type is usually seen among patients with atherosclerosis, smokers, diabetics, with scleroderma and Raynaud’s disease. [4, 7, 8]
A photo showing an example of autoamputation of a dry gangrene.
Otherwise known as moist gangrene, this type develops as sequela of untreated wound infections. “Wet” pertains to bacterial infection, particularly that of Clostridium perfringens, Bacillus fusiformis, Streptococci and Staphylococci. It is also pathologically characterized by liquefactive necrosis, mostly located among moist tissues and organs. [2, 4, 10]
In this type, the infection leads to swelling and inflammation, eventually causing blockage of blood supply within the area. The affected part is edematous, decayed, reddish to dark brown in hue, rancid and filled with pus and dormant blood, promoting further bacterial growth and subsequently, necrosis and gangrene. These bacteria can eventually form toxic byproducts, causing increased risks for both sepsis and death. [2, 4, 8, 10]
It usually complicates severe burns, injuries, trauma and even frostbites. It may also be present among diabetics, who have peripheral neuropathy and unknowingly injure their extremities. [5, 7]
An example of a burn patient with wet gangrene, having a decayed lesion, edematous and blistered.
Growing only without the presence of oxygen, Clostridia are the main etiologic agents of gas gangrene. They invade wounds and injuries with diminished blood supply, release gas-producing toxins and ultimately cause gangrene of muscles and organs. [5, 8]
The affected skin may appear grayish to purplish red in hue. Also apparent is a bubbly skin. It makes a crackling sound whenever pressed, particularly due to the presence of gas within. This gas is said to contain 16.1% oxygen, 5.9% hydrogen, 74.5% nitrogen, and 3.4% carbon dioxide. [2, 5, 9, 10, 12]
This type can lead to gas production, necrosis and severe infection, and eventually, may rapidly progress to shock and death. Hence, they are often pointed out as a medical emergency. 
A photo showing gas gangrene of the lower extremities.
This type affects the internal organs, hence the name. It usually involves the intestines, appendix and gallbladder. It occurs when blood circulation to any of these organs is interrupted, and is most frequently manifested by fever and severe pain. If left untreated, this may lead to death. An example of which is a gangrened herniated part of the intestine which bulged and protruded through a weakened area of the abdomen. [2, 5, 9]
Internal gangrene as found in the intestines during a surgical procedure.
This type involves the male genital organs and is usually a result of an infection of the genital region or the urinary tract. It is characterized by swelling, redness, and tenderness within the genital area. It usually affects diabetics, with chronic alcohol use and immunocompromised. If left untreated, the infection can extend into the circulation, cause sepsis and be lethal. [2, 5, 7, 9, 13]
This type is also known as Progressive Bacterial Synergistic Gangrene. Seen among patients post-operatively, it usually has Staphylococcus and Streptococcus as its etiologic agents. It is characterized by lesions with extreme pain, usually present within 2 weeks after surgery. [5, 9]
How Can Gangrene Be Diagnosed?
Apart from a thorough history and physical examination, gangrene can also be confirmed by a series of diagnostics. [ 3, 5]
- Blood tests: The level of white blood cell count can indicate infection.
- Culture of Tissue or Bodily Fluids: This can determine the presence of bacteria and determine the most effective antibiotic type to use.
- Blood Culture: It is indicative of bacterial growth.
- Imaging test such as x-rays, MRIs, and CT scans: It can confirm the extent of gangrene and identify blockages and interruption in blood circulation.
- Surgery: This is necessary to confirm the presence of gas and internal gangrenes.
Treatment Modalities in Managing Gangrene
Gangrene treatment is mainly focused on removing the affected tissue, preventing further infection and stopping the key agents of causation. These can be achieved by a number of methods. 
Oral, intramuscular or intravenous antibacterial agents can be utilized to defy the effects of infection and initiate healing. This can include an antipseudomonal and aminoglycosides. However, they are not effective when used single handedly. [3, 4, 14]
This is removal of dead tissue brought about by gangrene. This will prevent its extensive spread, and furthermore, allow the unaffected tissue to heal.
If gangrene is severe and complicated, amputation may be done. In fact, as of 2005, there were 30,000 to 40,000 amputations recorded yearly. [3, 15]
Hyperbaric Oxygen Therapy
In this method, the patient is placed on a pressurized chamber with a oxygen filled plastic hood placed on the damaged part of the body. High levels oxygen thus is dissolved in the bloodstream, increasing the healing process, and concomitantly inhibiting toxin production. Lasting for about 90 minutes, this is done thrice on the first day of therapy, with twice daily therapies for 5 days thereafter. This is used in the treatment of diabetic foot ulcers. [3, 5, 16]
- Lawrence, C. Gangrene. The Lancet. 2005 Nov; 366 (9498): 1689.
- Chi, C, et al. Gas Composition in Clostridium septicum Gas Gangrene. J. Formos Med Assoc. 1995 Dec; 94 (12).
- Levenson, R, et al. Fournier Gangrene: Role of Imaging. Radiographics. 2008 March to April; 28 (20): 519-28.
- Lipsky, B, et al. Evidence-Based Antibiotic Therapy of Diabetic Foot Infections. FEMS Immunol Med Microbiol. 1999 Dec; 26 (3-4): 267-76.
- Ziegler-Graham,K. et al. Estimating the Prevalence of Limb Loss in the United States: 2005 to 2050. Archives of Physical Medicine Rehabilitation. 2008 March; 89(3): 422-9.
- Slack, W. Hyperbaric Oxygen Therapy in Anaerobic Infections: Gas Gangrene. Proc R Soc Med. 1976 May; 69 (5): 326-7.