Gas gangrene

ICD-10 code

A48.0 Gas gangrene.

What causes gas gangrene?

Gas gangrene is caused by 4 species of spore-forming anaerobic clostridia: Clostridium perfringens, Clostridium oedematiens, Clostridium septicum, Clostridium histolyticum, and sometimes Clostridium novyi.

How does gas gangrene develop?

Clostridia are widespread in the external environment, mainly in the soil, where they exist in the form of spores and enter the human body through damage to the skin - abrasions, scratches.

• An important factor contributing to the development of anaerobic infection is impaired oxygenation.
• Typically, the situation arises with deep channels, poor communication of the cavity with the external environment, injury to the main vessel and prolonged application of a tourniquet to the limb, as well as in patients with chronic arterial insufficiency.
• A favorable background is the presence of a large mass of crushed and bruised tissue and factors that reduce the overall resistance of the body.
• Under anaerobic conditions, microorganisms begin to multiply rapidly, forming toxins that have a damaging effect on surrounding tissues and contribute to the rapid spread of necrosis.
• Clostridia secrete complex exotoxins consisting of several fractions, colloidal structure, which have a pronounced systemic and local effect; the most active fractions include:
  • lecithinase C (pronounced necrotizing and hemolytic action),
  • hemolysin (pronounced necrotizing effect, specific cardiotoxic effect),
  • collagenase (lyses protein structures),
  • hyaluronidase (penetration factor),
  • fibrinolysin,
  • neuraminidase (destruction of immune receptors on red blood cells),
  • hemagglutinin (inhibits phagocytosis) and others.
• The saccharolytic function leads to the destruction of glycogen, and the proteolytic function leads to the destruction of proteins and melting.
• Clostridia are characterized by gas formation and edema, with rapid spread along the vascular-nerve bundles and significantly ahead of the formation of edema of the skin and subcutaneous tissue.
• Under the influence of the toxin, thrombosis of veins and arteries, paralysis and impaired permeability of the vessels of the microcirculatory bed develop.
• Plasma and formed elements of the blood enter the necrosis zone.
• Local circulatory disorders contribute to the growth of necrosis, and the rapid absorption of bacterial toxins and decay products leads to severe intoxication and a decrease in systemic blood pressure.
• The incubation period of anaerobic clostridial infection lasts from several hours to 2-3 weeks, on average 1-7 days, and the shorter it is, the more severe the course and the unfavorable prognosis.

How does gas gangrene manifest itself?

Acute clostridial infection is characterized by a pronounced necrotic process, massive edema and gas formation.

• Crepitus is considered a specific symptom (when palpating under the fingers, there is a sensation similar to the crunch of snow).
• In most cases, the onset of the disease is violent, with the rapid development of severe intoxication.
• Classical clostridial infection is characterized by:
  • pronounced edema without hyperemia,
  • intense bursting pains,
  • blisters with hemorrhagic contents and greenish spots on the skin,
  • decrease in local temperature,
  • massive necrosis of connective tissue and muscle structures, imbibition by decay products, for this reason the muscles look like boiled meat, prolapse into the wound,
  • cloudy exudate of a non-purulent nature, often hemorrhagic, with an unpleasant odor,
  • Symptoms of gas accumulation: crepitus, the appearance of bubbles when pressing on the edge of the wound, and in X-ray examination, soft tissues are of a feathery and layered appearance.
• Anaerobic infection is characterized by rapid progression of local symptoms and spread of the process.
• After a few days, aerobic microflora with signs of purulent infection usually joins the anaerobic one.

Gas gangrene has four stages

In the early stage (limited gas gangrene), patients complain of pain. The wound is dry with a dirty-gray coating, necrosis is practically without discharge or with a small amount of brownish exudate. Edema is observed only around the wound, the skin in this area is tense, shiny, pale with a slight yellowish tint ("white edema", "white face").

The stage of spreading, as the process progresses, swelling and gas formation increase, and they spread along the limb. The nature of the pain changes, it becomes bursting. The tissues in the wound become lifeless, dry, the muscles bulge out of the wound, dull, fragile, bloodless. The yellowish-pale color of the skin spreads widely from the wound, bronze or marble spots are observed in the affected area.

In the third stage, the limb becomes cold, peripheral pulsation is not detected, pain stops, and its sensitivity is impaired. The limb is pale, sharply enlarged; edema and gases spread to the body, blisters with brown or hemorrhagic exudate are registered. The wound is lifeless, the muscles in it look like "boiled meat", bloody-purulent discharge is possible from the depth of the wound.

In the fourth stage (sepsis), there is purulent discharge in the wound, severe intoxication and distant purulent metastatic foci are observed.

Early symptoms of anaerobic infection: marked anxiety of the patient, agitation, verbosity, followed by extreme inhibition, adynamia, disturbances of orientation in time and space, elevated body temperature, tachycardia and hypotension. As the process progresses, liver and kidney failure develops, leading to parenchymatous jaundice, increasing due to toxic hemolysis, oliguria and anuria.

Classification

Gas gangrene has three forms:

• clostridial myositis (predominantly local muscle damage);
• clostridial cellulitis (predominantly affects the subcutaneous fat and connective tissue, perivascular and perineural sheaths);
• mixed form.

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How is gas gangrene recognized?

Gas gangrene is diagnosed based on an assessment of the nature of the pain syndrome, the rate of increase of edema and necrosis, the presence of crepitus, the nature of the exudate and the color of the skin.

• A decrease in the temperature of the affected limb is observed, in contrast to inflammation caused by non-clostridial infection.
• X-ray and ultrasound examinations reveal gas accumulation in soft tissues, with gas typically spreading through loose spaces of the cellular tissue with fragmentation of muscle segments.
• Laboratory tests: decreased hemoglobin and hematocrit levels, leukocytosis reaches 15-20x109/l with a shift in the leukocyte formula to the left, increased ESR.
• Bacterioscopy of wound discharge with Gram staining of the preparation shows “coarse”, unevenly thickened gram-positive rods, which confirms the diagnosis of clostridial infection.

Differential diagnostics

It is performed with anaerobic streptococcal myonecrosis, urinary infiltrates, crepitating cellulitis, and necrosis in diabetic angiopathy.

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How is gas gangrene treated?

The patient is isolated in a separate room; the sanitary and hygienic conditions in the room must exclude the possibility of contact spread of infectious agents.

It is necessary to carry out timely and adequate disinfection of medical instruments, equipment, premises, toiletries and dressings.

The pathogenetic treatment complex includes the following main components:

• adequate surgical debridement of the wound;
• prevention of the proliferation and spread of bacteria by oxygenating the site of infection, using antibacterial agents and specific serums;
• correction of changes in the functions of organs and systems using infusion and anticoagulant therapy, immunocorrection and immunostimulation;
• neutralization of the action of circulating toxin by the introduction of specific anatoxins and the use of extracorporeal detoxification methods.

Gas gangrene requires the use of three types of surgical interventions:

• wide dissection of the affected tissues - "lampas" incisions with opening of aponeuroses, fascial sheaths down to the bone, for the purpose of adequate aeration of the wound and removal of edema fluid containing a large amount of toxins;
• excision of affected tissues, primarily muscles;
• amputation (exarticulation) of a limb above the level of visually determined viable tissue, without the application of primary sutures.

Antibacterial therapy for clostridial infection until the sensitivity of the pathogens is determined is carried out with high doses of penicillin (20-30 million IU per day intravenously).

More effective is the use of a combination of penicillins and aminoglycosides, cephalosporins and aminoglycosides.

Drugs that selectively act on anaerobes are widely used: clindamycin (dalacin), chloramphenicol, metronidazole, carbenicillin, rifampicin, furazidine solutions, dioxidine, etc.

Serotherapy involves the administration of anti-gangrenous serums.

One ampoule of standard polyvalent serum contains anatoxins against three types of pathogens (Cl. perfringens, oedematiens, septicum) at 10,000 IU each. Clostridium histolyticum is rare.

In cases of extensive damage or severe wound contamination, a polyvalent anti-gangrenous serum is administered for prophylactic purposes at an average prophylactic dose of 30,000 IU.

Oxygen barotherapy (treatment in a pressure chamber under conditions of increased oxygen pressure) plays a major role in treatment; it helps reduce the number of pathogens and prevents the formation of resistant forms of microbes.

What is the prognosis for gas gangrene?

Gas gangrene has an unfavorable prognosis; patients recover with early diagnosis and timely and adequate treatment.