Gangrene – Hazard Identification and Prevention

Gangrene is a serious form of damage that affects quality of life and is very dangerous. These types of injuries require early prevention, diagnosis, and treatment. If left unchecked, the two worst outcomes, amputation and complete death, can occur. Gangrene is not uncommon, so let's learn about it.


1. Definition

Gangrene is a complication of gangrene. The essence of gangrene is necrotic tissue with infection.

Necrosis is the medical term used to describe a group of dead cells in the body. Usually gangrene is caused by:

  • Lack of oxygen to feed.
  • Physical injury.
  • Chemical damage.
  • Cellulolytic enzymes secreted by the body: This is a type of yeast that has both good and bad properties. If present in the intestine, it will help the body easily digest the food ingested. But if it occurs in necrotic tissue, this enzyme will destroy the body's tissue structure, creating easy conditions for bacteria to attack, spread around, and finally enter the bloodstream throughout the body.

2. Classification of gangrene lesions by shape:

There are main types of gangrene:

Dry gangrene:

Mainly due to anemia, this condition is most common in people with diabetes. Vascular lesions in this subject appeared mainly in the extremities.

Therefore, the damage will gradually spread from the tip of the finger up, to the part where the tissue has enough blood to feed, it will stop. In this form of lesions, few bacteria exist. This group of bacteria normally secretes Hydrogen sulfide.

Gangrene – Hazard Identification and Prevention

Dry gangrene

Hydrogen sulfide will combine with iron secreted by broken red blood cells. The final compound that causes the black color of gangrene is iron sulphide.

Gangrene – Hazard Identification and Prevention

The process of forming the black color of gangrene tissue

Wet necrosis

The tissue is initially swollen, usually due to a blockage in the venous system. Veins help carry blood from the tissues to the heart. When it is blocked, it will stagnate blood, at this time the vein will dilate and cause the surrounding tissue to swell.

Prolonged blood stasis will cause tissue to necrosis, then bacteria will have the opportunity to invade. A watery environment such as edema is a favorable environment for bacteria to grow. It will form gangrene, spread to healthy tissues, even into the bloodstream, can cause infection in the blood and death.

Lesions are usually black, swollen, contain pus, when broken, pus flows with a stench.

3. Gangrene in practice:

Different from pathologists. When faced with necrotic lesions, clinicians will divide into 3 cases:

3.1 Dry gangrene

Mainly caused by acute or chronic vascular injury. (2) (3) (5)

Acute vascular injury:

  • Arterial thrombosis
  • Vascular trauma
  • Cold burns. It is a burning condition when the skin is exposed to temperatures below 0 degrees Celsius for a long time.
  • Presence of many blood clots in many places on the body – DIC (Distributed Intravascular Coagulation).

These causes are often very serious, rapidly progressive, manifest acutely, may require amputation, or even more, are life-threatening.

Treatment is mainly based on the specific cause of the acute injury in the blood vessels.

Chronic vascular injury:

  • Peripheral vascular disease.
  • Varicose veins .
  • Hypertension.
  • Dyslipidemia.
  • Diabetes.
  • Smoke.
  • Immune diseases: Vasculitis, arthritis , blood clotting disorders.
  • Cancer.
  • In addition, peripheral vascular disease is also caused by: Connective tissue disease.

Of all the above causes, diabetic foot is the most common form of wet gangrene.

For diabetes, according to the Meggitt - Wagner diabetic foot classification, stage 4 is partial gangrene of the foot and stage 5 (also the final stage with gangrene of the whole foot). (4)

Diabetic foot gangrene is often located in the most stressed areas of the foot.

Gangrene – Hazard Identification and Prevention

The darkened area is the area that experiences the most pressure on the foot when standing - also the most prone to ulcers

In the case of chronic vascular injury, the patient may have the following symptoms: (2)

  • Intermittent pain.
  • Pain at rest.
  • Brittle nails that break easily.
  • Hard-to-heal ulcers.
  • Dry/wet gangrene.

Before gangrene occurs, we should try to treat the cause of these chronic lesions.

Manifestations of claudication (typical): (4)

  • Pain in the calf (back leg) when walking.
  • No pain when standing up or sitting down.
  • The pain does not go away as you keep walking.
  • Pain causes the patient to stop or slow down.
  • At rest, the pain subsides within 10 minutes.

However, the incidence of this typical intermittent claudication accounts for only about 11% of cases of chronic vascular injury.

Only about 55% of patients present with calf, thigh, or buttock pain on walking and do not meet the criteria for a diagnosis of typical claudication.

General surveys of both cardiac function (echocardiogram, electrocardiogram), blood vessels (measurement of lower extremity arterial blood pressure with the aid of doppler ultrasound) - to investigate the ABI (blood ratio) brachial-ankle pressure) can help diagnose this chronic vascular injury.

ABI Ratio:

  • 1 – 1.4: Normal, because ankle blood pressure is greater than or equal to arm blood pressure.
  • 0.5 – 0.8: Suggests moderate arterial disease.
  • < 0.5:="" disease="" reason="" dynamic="" circuit="">

CT scan of blood vessels when ABI suggests arterial disease. MRI is an alternative to CT scan of blood vessels. In addition, coagulation studies (D-Dimer) and CRP should now be considered.

Primary treatment of chronic vascular injury:

To prevent further tissue necrosis, it is important to identify and treat the underlying disease well.

If left untreated, dry gangrene can progress to wet gangrene and the main treatment at this time is amputation (amputation), antibiotics.

See also: Pyoderma gangrenosum: a rare scary lesion

3.2 Wet gangrene: (5)

As listed above, wet gangrene usually occurs on the stasis of blood due to venous obstruction, this environment favors bacterial growth.

Wet gangrene occurs mainly from environments that are already wet:

  • Oral mucosa, gastrointestinal tract (esophagus, stomach, small intestine, large intestine).
  • Respiratory mucosa.
  • Cervical.
  • The vulva (female external genitalia).

In which, the mucosa is the layer of cells covering the inside of the organs, the place of contact between the body and food, between the body and the outside air. These sites often contain a wide variety of bacteria.

In subjects with diabetes, foot ulcer complications, often a combination of 3 factors:

Neuropathy in the leg region:

  • Reduced muscle strength, making it more susceptible to injury under pressure.
  • Loss of sensation should not feel pain when the injury.
  • The mobility of the joint when changing the walking and running position is also lost, so it is easy to get injured.
  • Affects the autonomic nervous system to reduce foot sweat, dry feet, easy injury.

Lack of blood supply (due to atherosclerosis).

High blood sugar (causes the body's immune deficiency).

Since then, diabetics are very susceptible to infections, especially in the feet. Therefore, wet necrosis also occurs easily in this group of patients. In this situation, infection plays a secondary role, accelerating necrosis.

When wet necrosis has taken place, the disease will progress rapidly, easily die.

Amputation is usually the right choice.

3.3 “Necrotizing soft tissue infection” (6) (7) (8)

Necrotizing soft tissue infection is an infection that is the main cause of tissue necrosis, unlike the above two phenomena, infection is just a secondary factor!!!

Group 1:

(Multi-bacterium group)

Found in 55-75% of soft tissue infections causing necrosis.

There may also be Clostridium perfingens (which are abundant in the soil). However, this case has been greatly reduced. Mainly because people today have a sense of washing and disinfecting wounds.

Today's major risk factors for group 1 necrotizing soft tissue infections are people with multiple medical conditions and often unrecognized trauma (7).

A good example of this type is Fournier gangrene. This is a common lesion on the trunk, neck, and around the anus.

Group 2:

(Infected with a single germ).

The most common organism is group A beta-hemolytic streptococcus. Less commonly, methicillin-resistant Staphylococcus aureus (usually in patients with nosocomial infections).

Subjects are often young people with wounds on their hands and feet (including surgery and syringes).

Group 3:

Caused by flesh-eating bacteria (Vibrio vulnificus), common in Asians with wounds exposed to dirty water.

Group 4:

Fungal soft tissue necrosis, common in immunocompromised subjects (HIV/AIDS…)

The progression of these lesions is relatively rapid, about 2.5cm/hour (#1inch/hour).

General symptoms of necrotizing soft tissue infection:

  • The patient feels a lot of pain, anxiety and fatigue.
  • Pain in the affected area is the earliest symptom of inflammation. At first, the pain is less, then gradually increases, and finally, the patient loses feeling in the affected area.
  • Symptoms usually begin within 48 hours of the injury.

Early warning table of “necrotizing soft tissue infection” lesions:

Gangrene – Hazard Identification and Prevention

When patient <6 points,="" 94%="" disease="" multiply="" no="" yes="" infection="" infection="" tissue="" soft="" causes=" " ruin="" death.="" field="" match="" from="" 6="" points="" up="" up="" 92%="" disease="" multiply=" " yes="" infection="" infection="" tissue="" soft="" damage="">

Imaging studies for the diagnosis of necrotizing soft tissue infection are often unhelpful and unnecessary.

A special form of necrotic soft tissue infection: Gas gangrene. (6) (7) (8)

As mentioned above, this is a special form of necrotic soft tissue infection, usually in group 1. In other words, gas gangrene is also the key bacterial necrosis disease.

This lesion is caused by the patient being infected with a specific bacterium called Clostridium perfingen.

This bacteria exists in abundance in sandy soil as well as in the digestive tract.

Clostridium perfingen is a type of bacteria that is afraid of the air. Therefore, deep, dirty, blood-depleted lesions - without oxygen coming in, are favorable conditions for them to change from an inactive form to an active form.  

The characteristic of this type of bacteria is that although the damage is only located in a certain area, they will secrete their toxins into the blood, making us toxic.

Their toxin is α-toxin, this toxin can destroy the body's cells, destroy red blood cells, suppress the immune system, form blood clots in many places in the body, and damage surrounding tissue and the vascular system. nearby blood.

This toxin can be neutralized by the body in a few hours but the patient can die before the body can successfully neutralize itself – due to its intense toxicity, and its ability to attack very quickly.

Diagnosis of gas gangrene:

When the patient has the following suspicious signs:

  • Usually the wound is dirty, deep, located in the private area, air cannot reach (in the abdomen, vagina, uterus ...).
  • The damaged area quickly swells, painful, and exudes fluid.
  • Lesions will spread beyond the surrounding area rapidly, with mottled brown staining. This is followed by the appearance of vesicles and finally necrotic (black) tissue.
  • Subcutaneous emphysema (pressing on the skin near the lesion with a crackling sound) is a typical but uncommon sign.
  • Symptoms of toxic shock (tachycardia, hypotension, excitability) occur rapidly without fever. Patients easily die if not detected and treated promptly.
  • Bacterioscopy (microscopic examination with special dyes): Specimens for examination are exudates from lesions. Detected rod-shaped bacteria, gram-positive, with very few immune cells. 

Gangrene – Hazard Identification and Prevention

The microscopic image of Clostridium perfingens was stained.

General treatment strategy for necrotizing soft tissue infections.


The first is Clindamycin and will be combined with other antibiotics.

Hyperbaric oxygen therapy (the patient breathes a much larger amount of oxygen than usual)

To inhibit the growth of airborne bacteria. When this therapy is started early, mortality is reduced (to about 20-30%). And amputation is not required in 80% of cases, compared with 40 to 50% without treatment.

Complications of hyperbaric oxygen therapy:

  • Injury to the middle ear (eardrum).
  • Oxygen poisoning.


Initially, only surgery should be made to open the wound, cut the pseudomembranous membranes to allow air to easily access bacteria

Subsequent amputation can be performed when the boundary between the gangrene and the healthy area becomes clear, and the damage is irreversible. This is to preserve the patient's other living tissues.

Gangrene is the final manifestation of necrosis and infection. Treatment usually consists of 3 steps, antibiotics, ablation/amputation, and hyperbaric oxygen therapy.

Early detection to prevent gangrene from occurring is essential.

Gangrene is an infected necrotic lesion, but it should be remembered that the infection itself is a contributing cause of the necrosis. Therefore, not only dry necrosis can turn into wet necrosis. A common skin infection can also be a trigger for necrosis, gangrene formation.

Death, amputation are the final outcomes, no one wants. So, when you experience a discolored (red, red, oozing) skin lesion that spreads rapidly, regardless of previous trauma, and is accompanied by fatigue, lethargy, and fatigue, make an appointment. Immediately go to the emergency department of the nearest hospital. That may be the only chance to keep the patient from death.

Doctor Nguyen Doan Trong Nhan

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