| disease | Gas Gangrene |
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 surgery.
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. The gas gangrene seen clinically 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 perfringens but more by the body's resistance and the condition of the wound, namely, an oxygen-deficient environment conducive to the growth and reproduction of Clostridium perfringens. 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 prone to lead to gas gangrene.
The causative bacteria of gas gangrene primarily grow and reproduce within wounds and rarely invade the bloodstream to cause sepsis. Clostridium perfringens produces toxins such as alpha-toxin, collagenase, hyaluronidase, fibrinolysin, and deoxyribonuclease. The destruction of red blood cells leads to hemolysis, hemoglobinuria, oliguria, necrosis of renal tissue, edema, liquefaction, and extensive muscle necrosis, causing the lesion to rapidly spread and worsen. The breakdown of carbohydrates generates large amounts of gas, causing tissue swelling. The decomposition of proteins and liquefaction of gelatin produce hydrogen sulfide, resulting in a foul odor from the wound. Due to local ischemia, plasma exudation, and the effects of various toxins, the tissues and muscles in the wound further necrotize and decay, further facilitating bacterial proliferation and worsening the condition. The extensive tissue necrosis and absorption of exotoxins can lead to severe toxemia. Certain toxins can directly invade the heart, liver, and kidneys, causing focal necrosis and impairing the function of these organs.
bubble_chart Clinical ManifestationsThe incubation period can be as short as 6 to 8 hours, but generally lasts 1 to 4 days.
Local manifestations The patient feels heaviness in the affected area, as if it were tightly bandaged. Subsequently, there is a sudden onset of "bursting-like" severe pain 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, along with thin, foul-smelling serosanguineous discharge.
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, including a drop in blood pressure, and finally jaundice, delirium, and unconsciousness.
Early diagnosis and timely treatment are crucial for preserving the injured limb and saving lives. Therefore, diagnosis should be made as soon as possible. The diagnosis is primarily based on clinical manifestations, examination of wound secretions, and X-ray findings. For instance, if unusual pain occurs at the wound site after an injury or surgery, accompanied by 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 examination 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.
bubble_chart Treatment MeasuresGas 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 management While rescuing severe shock or other serious complications, emergency local surgical intervention is required. Before surgery, intravenous infusion of 2 million units of penicillin and 0.5g of tetracycline should be administered. General anesthesia is typically used, and tourniquets should be avoided. During the operation, attention should be paid to oxygen administration, continued blood transfusion, fluid infusion, and antibiotic use. Extensive and multiple incisions should be made in the affected area (including the wound and surrounding edema or subcutaneous gas-filled swelling), removing nonviable muscle tissue until muscles with normal color, elasticity, and fresh bleeding are reached. The wound should be left open and repeatedly irrigated with a large amount of 3% hydrogen peroxide solution or 1:4000 potassium permanganate solution. Postoperatively, the wound should remain open, with hydrogen peroxide wet dressings applied and changed several times a day.
Amputation should be considered under the following circumstances: 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 not affected. The amputation stump should not be sutured but treated with hydrogen peroxide wet dressings, and further revision can be done after wound healing.
2. Hyperbaric oxygen therapy Under three atmospheres of pure oxygen, the oxygen physically dissolved in the blood increases approximately 20-fold compared to normal levels, enhancing tissue oxygen content, inhibiting the growth and reproduction of gas gangrene bacilli, and stopping their production of alpha toxin. Generally, seven treatments are administered over three days, one every 2 hours, with intervals of 6–8 hours. On the first day, three treatments are given, followed by two each on the second and third days. After the first treatment, the wound should be examined, and necrotic tissue removed, but extensive debridement or excision to healthy tissue is not necessary. Further debridement can be repeated as needed. Many limbs can retain function through this treatment. It has also been observed that patients who complete five hyperbaric oxygen treatments 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) should be used, which can also control suppurative infections and reduce the hypoxic environment caused by oxygen consumption from other bacterial proliferation at the wound site. Once toxemia symptoms and local conditions improve, the dose can be reduced or discontinued. For patients allergic to penicillin, erythromycin (1.5–1.8g/day) can be administered intravenously.
4. Systemic supportive therapy Transfuse blood in small amounts multiple times, correct typical edema and electrolyte imbalances, provide a high-protein, high-calorie diet, and administer pain relief, sedation, and fever reduction as needed.
Gas gangrene antitoxin serum has poor efficacy in preventing or treating gas gangrene, only providing temporary relief of toxemia symptoms. Moreover, it carries the risk of allergic reactions in patients and is now rarely used.
Thorough debridement is the most reliable method to prevent gas gangrene after trauma. Debridement within 6 hours of injury can almost completely prevent the occurrence of gas gangrene. Even if the injury has exceeded 6 hours, debridement can still provide good preventive effects with the use of large amounts of antibiotics. Therefore, for all open wounds, especially those contaminated with soil or with severe injury and nonviable muscle, 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 left open.
Penicillin and tetracycline antibiotics are effective 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.
1. Clostridial Cellulitis The infection is confined to the subcutaneous cellular tissue and spreads rapidly along the fascial membrane 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 mild, the skin rarely changes color, and edema is also slight.
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 mild. Emphysema and crepitus are present, but the emphysema is limited to the subcutaneous tissue and fascial membrane. There are general inflammatory manifestations around the wound. The exudate is seropurulent, and streptococci can be found on smear examination.
3. Coliform Bacterial Cellulitis Tissue intermediate qi swelling may occur, along with toxemic symptoms such as high fever and delirium. However, local swelling develops slowly, and the pus exhibits the characteristics of coliform bacterial infection—thin and serous. Smear examination of the pus may reveal Gram-negative bacilli.
