Gas gangrene is a severe acute specific infection caused by Clostridium bacteria. Depending on the extent of the lesion, clostridial infections are divided into two categories: clostridial myonecrosis and clostridial cellulitis. The commonly referred gas gangrene is clostridial myonecrosis, which primarily occurs in patients with extensive muscle tissue injuries, and rarely in wounds following abdominal or perineal surgeries.

bubble_chart Etiology

Clostridium is a Gram-positive anaerobic bacillus, with Clostridium perfringens (Wei's bacillus), Clostridium oedematiens, and Clostridium septicum being the most common, followed by Clostridium sporogenes and Clostridium histolyticum, among others. Clinically observed gas gangrene is often a mixed infection caused by two or more pathogenic bacteria.

Clostridium is widely present in soil and the feces of humans and animals, making it easy to enter wounds, but it does not necessarily cause disease. The occurrence of gas gangrene is not solely determined by the presence of Clostridium bacteria but more so by the body's resistance and the condition of the wound—namely, an oxygen-deficient environment conducive to the growth and reproduction of Clostridium bacteria. Therefore, conditions such as dehydration, massive blood loss or shock, combined with extensive tissue necrosis in the wound, deep muscle damage (especially injuries to the thigh and buttocks), retained shrapnel, open fractures, or injuries to major blood vessels, as well as prolonged use of tourniquets, are all factors that increase the likelihood of gas gangrene.

bubble_chart Pathogenesis

The causative bacteria of gas gangrene primarily grow and reproduce within the wound and rarely invade the bloodstream to cause septicemia. Clostridium perfringens produces toxins such as alpha toxin, collagenase, hyaluronidase, fibrinolysin, and deoxyribonuclease. The destruction of red blood cells leads to hemolysis, hemoglobinuria, oliguria, renal tissue necrosis, edema, and liquefaction, while extensive muscle necrosis causes rapid spread and worsening of the lesion. The breakdown of carbohydrates generates large amounts of gas, causing tissue distension. The decomposition of proteins and liquefaction of gelatin produce hydrogen sulfide, resulting in foul-smelling wounds. Due to local ischemia, plasma exudation, and the effects of various toxins, the tissues and muscles within the wound further necrotize and decay, creating a more favorable environment for bacterial proliferation and exacerbating the condition. The extensive tissue necrosis and absorption of exotoxins can lead to severe toxemia. Certain toxins may directly invade the heart, liver, and kidneys, causing focal necrosis and impairing the function of these organs.

The incubation period can be as short as 6 to 8 hours, but is generally 1 to 4 days.

Local manifestations

The patient feels heaviness in the affected area, as if it were tightly bandaged. Subsequently, sudden "bursting-like" severe pain occurs in the affected area, which cannot be relieved by ordinary analgesics. The affected area shows obvious swelling and severe tenderness. The skin around the wound becomes edematous, tense, pale, and shiny, quickly turning purplish-red and then purplish-black, with blisters of varying sizes appearing. The muscles in the wound, due to necrosis, appear dark red or earthy gray, lose elasticity, and do not contract or bleed when cut, resembling cooked meat. Crepitus is often palpable around the wound, indicating the presence of gas in the tissues. Gently squeezing the affected area often causes bubbles to escape from the wound, accompanied by thin, foul-smelling serosanguineous secretions.

Systemic symptoms

In the early stage, the patient appears apathetic, with dizziness, headache, nausea, vomiting, cold sweating, dysphoria, high fever, rapid pulse (100–120 beats/min), labored breathing, and progressive anemia. In the advanced stage, severe toxic symptoms appear, blood pressure drops, and finally jaundice, delirium, and unconsciousness occur.

bubble_chart Diagnosis

Early diagnosis and timely treatment are crucial for preserving the injured limb and saving lives. Therefore, diagnosis should be made as soon as possible. Diagnosis is primarily based on clinical manifestations, examination of wound secretions, and X-ray findings. If, after an injury or surgery, the wound exhibits unusual pain, rapidly increasing local swelling, crepitus in the surrounding skin, and severe systemic toxic symptoms such as accelerated pulse, dysphoria, restlessness, and progressive anemia, the possibility of gas gangrene should be considered. The presence of a large number of Gram-positive bacilli in a smear of wound secretions and the detection of gas between muscle groups on X-ray are three key diagnostic criteria for gas gangrene. Although anaerobic bacterial culture and pathological biopsy can confirm the diagnosis, they require time and should not delay treatment while awaiting results.

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Gas gangrene progresses rapidly, and if treatment is deficient, patients often lose limbs or even die. Therefore, once diagnosed, aggressive treatment should be initiated immediately.

1. Emergency surgical intervention: While rescuing severe shock or other serious complications, emergency local surgical treatment must be performed. Before surgery, administer 2 million units of penicillin and 0.5g of tetracycline intravenously. General anesthesia is usually preferred, and tourniquets should not be used. During surgery, ensure oxygen supply, continue blood transfusions, intravenous fluids, and antibiotic administration. Make extensive and multiple incisions in the affected area (including the wound and surrounding edema or areas of subcutaneous gas accumulation), excising non-viable muscle tissue until normal-colored, elastic muscle that bleeds fresh blood is reached. Rinse the open wound repeatedly with large amounts of 3% hydrogen peroxide solution or 1:4000 potassium permanganate solution. Postoperatively, keep the wound open and apply hydrogen peroxide-soaked dressings, changing them several times a day.
   Amputation should be considered under the following conditions: a. All layers of tissue in the affected limb are involved and progressing rapidly; b. The limb injury is severe, combined with comminuted open fracture or major vascular injury; c. Infection cannot be controlled after debridement, with severe toxemia. The amputation site should be in healthy tissue where muscles are unaffected. The amputation stump should not be sutured but dressed with hydrogen peroxide-soaked gauze, and further revision can be done after wound healing.
2. Hyperbaric oxygen therapy: Under three atmospheres of pure oxygen, the physically dissolved oxygen in the blood increases approximately 20-fold compared to normal levels, enhancing tissue oxygenation, inhibiting the growth and reproduction of gas gangrene bacilli, and stopping their production of alpha toxins. Generally, seven treatments are administered over three days, with one session every 2 hours and intervals of 6–8 hours. On the first day, three sessions are performed, followed by two sessions each on the second and third days. After the first treatment, inspect the wound and excise necrotic tissue, but avoid extensive debridement or resection into healthy tissue. Subsequent debridement can be repeated as needed. This treatment preserves limb function in many cases. It has also been observed that patients who complete five hyperbaric oxygen sessions within the first 48 hours almost always survive. However, this requires hyperbaric oxygen chamber equipment, making it difficult to apply in field conditions.
3. Antibiotics: High-dose penicillin (10 million units/day) and tetracycline (2g/day) are used to control suppurative infections and reduce hypoxia caused by oxygen consumption from other bacterial growth at the wound site. Once toxemia symptoms and local conditions improve, the dosage can be reduced or discontinued. For penicillin-allergic patients, erythromycin (1.5–1.8g/day) can be administered intravenously.
4. Systemic supportive therapy: Administer small, frequent blood transfusions, correct typical edema and electrolyte imbalances, provide a high-protein, high-calorie diet, and manage pain, sedation, and fever reduction.

bubble_chart Prevention

Thorough debridement is the most reliable method to prevent gas gangrene after trauma. Debridement within 6 hours after injury can almost completely prevent the occurrence of gas gangrene. Even if the injury has exceeded 6 hours, debridement can still play a good preventive role with the use of large amounts of antibiotics. Therefore, for all open wounds, especially those contaminated with soil or with severe injuries and nonviable muscles, thorough debridement should be performed promptly. For war wounds, after debridement, the wound should generally be left open for drainage and not sutured.

For wounds suspected of gas gangrene, 3% hydrogen peroxide or 1:1000 potassium permanganate solution can be used for irrigation and wet dressing. For wounds that have already been sutured, the sutures should be removed and the wound opened.

Penicillin and tetracycline antibiotics have a good effect in preventing gas gangrene and can be used before or after debridement depending on the trauma situation. However, they cannot replace debridement.

The patient should be isolated, and all clothing, dressings, and equipment used by the patient should be collected separately and disinfected. Boiling disinfection should last for more than 1 hour, and high-pressure steam sterilization is preferred. Used dressings should be destroyed to prevent cross-infection.

bubble_chart Differentiation

1. Bacillary Cellulitis: The infection is confined to the subcutaneous cellular tissue and spreads rapidly along fascial spaces but does not invade the muscles. The onset is generally slow, with an incubation period of 3 to 5 days. Although it also begins with wound pain and there is crepitus around the wound, the local pain and systemic symptoms are milder, the skin rarely changes color, and edema is also mild.
2. Anaerobic Streptococcal Cellulitis: The onset is relatively slow, often appearing 3 days after the injury. Symptoms such as toxemia, pain, local swelling, and skin changes are all milder. Emphysema and crepitus are present, but the emphysema is limited to the subcutaneous tissue and fascia. There are general inflammatory manifestations around the wound. The exudate is seropurulent, and streptococci are found on smear examination.
3. Coliform Bacillary Cellulitis: Intermediate tissue gas swelling may occur, along with toxemic symptoms such as high fever and delirium. However, local swelling develops more slowly, and the pus exhibits characteristics typical of coliform bacillus infection—thin and serous. Gram-negative bacilli can be detected on smear examination of the pus.