Deadly skin infection: Necrotizing fasciitis

Recently, a large number of patients with "necrotizing fasciitis" have come to our department for treatment. Most of them have survived life-threatening rescue efforts.

For example, Mr. Chen had a small abscess on his back. He did not take it seriously and received cupping treatment at the village clinic for 2 weeks. However, the swelling and pain in his back did not improve, but became more and more severe. He also had chills and high fever, could not stand normally, could not sleep at night, and could not eat. So Mr. Chen came to our outpatient department for treatment. The doctor told him that he was not suffering from a small abscess but necrotizing fasciitis, and immediately arranged for Mr. Chen to be hospitalized for emergency surgery.

When he was admitted to the hospital, Mr. Chen was in very poor condition, with high fever, anemia, hypoproteinemia, high blood sugar, and varying degrees of abnormalities in coagulation function, liver and kidney function. On the night of his admission, he underwent emergency incision and drainage of the back abscess. During the operation, it was found that Mr. Chen's back skin was necrotic, a large amount of yellow-white pus was visible in the subcutaneous fascia layer, and there was a large area of ​​necrotic tissue in the abscess cavity. After the operation, he was given supportive treatment such as anti-infection and fluid infusion to correct hypoproteinemia.

After the patient's general condition stabilized, back debridement was performed again to remove necrotic tissue in the wound. During the operation, the back wound was found to be approximately 30cm*40cm in size. At the same time, a portable negative pressure wound therapy (NPWT) system was applied to the back wound. After two debridements and negative pressure treatments, the patient's general condition improved significantly, and he was discharged from the hospital with the portable negative pressure wound therapy system.

After one week of recuperation, the patient was hospitalized again. The doctors of our department's wound treatment team decided to perform one last operation on Mr. Chen to close the wound. During the operation, it was found that the necrotic tissue on the back wound had been removed and the granulation tissue was fresh, so the conditions for closing the wound were met. However, the patient's back skin was partially necrotic and could not be sutured directly, so a local skin flap transfer was used to complete the coverage of the back wound.

1. What is necrotizing fasciitis

What kind of disease is this that is so dangerous? Necrotizing fasciitis sounds unfamiliar and is not well known to everyone, but it is a very dangerous soft tissue infection, a bacterial infection of the fascia tissue.

Fascia is a basic structure in the human body that fills the entire body. It not only gives the body its internal and external shape, but also provides a support structure for all other systems of the body, such as the circulatory, nervous and lymphatic systems. It is considered the "skeleton" of soft tissue.

Fascia is formed by collagen synthesized and secreted by specialized fibroblasts, and the function of fascia is also provided by collagen. First, collagen is sticky, which can bind the cell matrix to the tissue. Secondly, these collagens are arranged in a wavy shape. When the body tissue is pulled by external forces, these wavy collagens can effectively resist stretching and shearing, preventing the body tissue from being easily torn apart. Fascia is divided into deep and superficial types throughout the body. Superficial fascia is located under the skin and is composed of loose connective tissue, mostly containing fat. It is also the layer most easily damaged by liposuction surgery. A more serious complication is necrotizing fasciitis.

The skin infection of patients with necrotizing fasciitis spreads rapidly along the subcutaneous fascia tissue, accompanied by a large amount of tissue necrosis. The infection and necrosis promote each other, making the infection difficult to control. If there is a slight delay, the limbs may be destroyed at best, and toxic shock may occur at worst, which is life-threatening.

Who may get necrotizing fasciitis?

Acute necrotizing fasciitis is common in patients with diabetes, peripheral vascular disease, immunodeficiency, drug abuse, alcoholism, obesity and elderly diseases. In the early stage, it often presents with fever and cellulitis. Its pathogens include Staphylococcus aureus, anaerobic bacteria, Gram-negative bacteria, and even fungi. Acute necrotizing fasciitis sometimes develops slowly at the onset, with cellulitis as the main symptom. Doctors who receive the patient often think it is a common surgical infection and do not pay enough attention to it, which can easily lead to misdiagnosis and missed diagnosis.

Diabetes is a particularly important risk factor. The patients with "necrotizing fasciitis" mentioned at the beginning all have a history of diabetes and poor blood sugar control.

3. Clinical manifestations and signs

1. Local symptoms

(1) Flaky redness, swelling, and pain: In the early stage, the skin is red and swollen, with unclear boundaries and pain. At this time, the subcutaneous tissue has been necrotic, and because the lymphatic channels have been destroyed, there is little lymphangitis and lymphadenitis. In some cases, the onset may be slow and the disease is latent in the early stage. The affected skin is red or white, edematous, and tender. The lesion boundaries are unclear and diffuse cellulitis is present. Subcutaneous crepitus can be felt due to subcutaneous gas accumulation.

(2) Pain relief and numbness of the affected area. Due to the stimulation of inflammatory tissue and the invasion of pathogens, there is severe pain in the early infection area. However, after the sensory nerves in the lesion area are destroyed, the severe pain can be replaced by numbness and paralysis, which is one of the characteristics of this disease.

(3) Bloody blisters: Due to the destruction of nutrient blood vessels and vascular embolism, the skin color gradually turns purple and black, and blisters or bullae containing bloody fluid appear.

(4) Bloody exudate with a strong odor: Subcutaneous fat and fascia edema, the exudate is sticky, turbid, and black, and eventually liquefies and necrotizes. The exudate is a bloody serous fluid with a strong odor. The necrosis spreads widely and insidiously, sometimes producing subcutaneous gas, and examination may reveal crepitus.

2. Systemic poisoning symptoms

In the early stage of the disease, the local infection symptoms are still mild, but the patient has severe systemic poisoning symptoms such as chills, fever, anorexia, dehydration, impaired consciousness, hypotension, anemia, jaundice, etc., which may be accompanied by hypotension and tachycardia. This manifestation is different from general local infections such as cellulitis and abscesses. If not treated in time, disseminated intravascular coagulation and septic shock may occur. Once disseminated intravascular coagulation and septic shock occur, the clinical mortality rate will double, and it should be taken seriously. The asymmetry of the severity of local symptoms and systemic symptoms is one of the main characteristics of this disease.

3. Physical signs

(1) Extensive necrosis is seen in the superficial subcutaneous fascia, with extensive tunnel-like spread into the surrounding tissues.

(2) Severe systemic poisoning symptoms, accompanied by changes in mental status.

(3) The lesion does not involve the muscles.

IV. Laboratory and other auxiliary examinations

Including blood routine, serum electrolytes, blood sugar, urine routine, blood cytology, serum antibodies, imaging examination, biopsy, ultrasound examination, etc.

5. How to diagnose

(1) Extensive superficial fascial necrosis with mild to moderate subcutaneous cellulitis.

(2) There is a wide undercover edge around the skin, the skin is pale and has water scars and blood scars.

(3) There is bloody serous or purulent exudation.

(4) In cases of mixed infection with aerobic and anaerobic bacteria, there is gas under the skin and the pus has a fecal odor. Therefore, it needs to be differentiated from gas gangrene, which is mainly characterized by extensive muscle necrosis.

How to treat it?

It is very important to understand acute necrotizing fasciitis and diagnose it early. Once diagnosed, surgical debridement is the key to treating the disease. The location of necrotic fascia is often hidden and difficult to find, and repeated surgery is required to completely remove the necrotic tissue. The traditional treatment plan is to mechanically remove the necrotic fascia through multiple surgeries and repeatedly change the dressings. The dressing change process is also extremely painful for the patient. At present, the method of multiple debridement in stages + NPWT is more commonly used to treat acute necrotizing fasciitis. Each operation is performed as short as possible to avoid a large amount of blood loss and achieve good results. NPWT can continuously and effectively drain the pus from the wound and prevent the abscess from forming again; its continuous and uniform negative pressure suction can improve local blood circulation and stimulate the growth of granulation tissue; after the granulation tissue on the wound is fresh, direct suture, skin grafting or flap transfer is used to cover the wound. Auxiliary treatments include: systemic supportive treatment (correction of water and electrolyte imbalance, anemia, hypoproteinemia); elemental diet; hyperbaric oxygen therapy, etc.

In summary, we must be vigilant about necrotizing fasciitis. For rapidly developing skin and soft tissue infections, we must seek medical attention in a timely manner to ensure early diagnosis and early treatment. At the same time, we must remind everyone to develop good eating and living habits to improve their immunity. If you have chronic systemic diseases such as diabetes, you must control your condition.

(Zhang Tao, Liangxiang Hospital, Fangshan District, Beijing)