Secondary mediastinal infection

Introduction to secondary mediastinal infection The plane of the neck fascia is directly connected to the anatomical plane of the upper mediastinum and the gap of the organ. The structure and plane of the lower mediastinum also communicate with the upper part of the retroperitoneal region through the fascia. An infection originating from a regional gap in the upper region can directly enter another anatomical region through this anatomical region, especially the infection originating from the neck, not only because of gravity, but also due to the negative pressure of the chest cavity spreading down into the mediastinum. The above gaps and channels, from the anatomical point of view, there are posterior pharyngeal space, anterior tracheal space, posterior sternal space, cervical vascular sheath and esophageal space, etc. In recent years, the number of cases of sternal midline sawing for cardiovascular surgery has increased. The incidence of postoperative mediastinal infection also increases. basic knowledge The proportion of illness: 0.038% Susceptible people: no specific population Mode of infection: non-infectious Complications: shock, esophageal perforation, bacteremia, sepsis

Secondary mediastinal infection

The most common pathogens of mediastinal infection are staphylococci, such as Staphylococcus aureus, Staphylococcus aureus or Staphylococcus epidermidis, others are Gram-negative Enterobacter, such as Enterobacter aerogenes, Alcaligenes and Proteus, Clostridium Pseudomonas aeruginosa, in recent years due to the conventional use of broad-spectrum antibiotics, Staphylococcus aureus has been rare, pus bacterial culture is often negative, in the chronic infection cases often found mold, such as Candida albicans.

Different causes of esophageal, tracheal and bronchial rupture can cause suppurative mediastinal infection.

(1) acute upper mediastinal infection, mostly caused by neck or chest esophageal injury; for example, esophagoscopy, causing iatrogenic injury, esophageal foreign body penetration through the esophageal wall, etc., the previous hard metal tubeoscopy is easier to produce This perforation.

(2) Esophageal and gastric anastomosis caused by esophageal surgery is also a common cause of acute mediastinal infection, but this inflammation spreads rapidly into the thoracic cavity, covering the acute mediastinal infection problem, spontaneous esophagus induced by severe vomiting When ruptured, it mainly produces fatal mediastinal infection.

(3) through the tracheal anterior space, pharyngeal space, anterior intervertebral space can cause upper mediastinal infection, because the neck is superficial, easy to drain with antibiotics is also easy to control, so the neck cellulitis, acute lymphadenitis progress Acute upper mediastinal infection is also a cause of mediastinal infection. Intrathoracic suppurative lesions, such as empyema, adjacent to the mediastinum, can also be spread directly into the mediastinum, from acute suppurative pericarditis and retroperitoneal The infection of the mediastinum caused by the infection of the area is extremely rare. In patients undergoing cardiac surgery, especially in the case of median incision, in patients who need tracheotomy after surgery, the tracheal incision and the posterior sternal space are connected due to the separation of the sternal fossa during surgery. Intravenous secretion of some tracheal endocrine into the mediastinum causes infection of the mediastinum, which is often reported in clinical practice.

Secondary mediastinal infection prevention

1. The sternum should be straightened. If the sternum is squatted, it will cause the sternum to traverse.

2. Intraoperative hemostasis is imperfect, excessive use of bone wax, electrocautery, poor drainage tube, blood clot accumulation and reopening of the chest have increased the possibility of infection.

3. It is reliable to fix the pectoral muscle through the sternal intercostal space. The adult is not less than 5-6 wires. Culliford believes that 2 wires are placed on the sternum stem, and 4 wires are better placed in the sternal intercostal space.

4. The pectoralis major fascia covers the wire and sternal space.

5. The pericardium should be sutured as much as possible to prevent infection from invading the pericardial cavity and causing major bleeding in the heart.

6. For cases with severe cough and cough, if there is a possibility of sternal splitting, fix it with a chest strap.

7. Generally, tracheotomy should be performed 5 to 7 days after operation. At the same time, care should be taken after tracheotomy to prevent wound infection.

Secondary mediastinal infection complications Complications, shock, esophageal perforation, septicemia

Multiple organ failure and toxic shock, the complications of mediastinal infection are more dangerous, because the bacteria causing infection are mostly intestinal pathogenic bacteria, and such pathogenic bacteria enter the tissue and produce strong pathogenicity, leading to surrounding tissues. Extensive necrosis, if accompanied by perforation of the esophagus, many of the highly harmful bacteria contained in the mouth can cause very serious poisoning. Bacteria or toxins are absorbed through the mediastinum-rich lymphatic network, and bacteremia, toxemia and sepsis are quickly produced. Even complicated with toxic shock, the disease can also cause pericarditis, pleural empyema, cardiopulmonary failure and macrovascular corrosive lethal bleeding.

Symptoms of secondary mediastinal infection Common symptoms Heart rate increased chills shock shock purulent secretions high fever dyspnea severe pain coughing subcutaneous emphysema

The main clinical manifestations of secondary mediastinal infection are fever, pain and purulent secretion. The patient's postoperative temperature does not retreat. It rises above 39 °C within 1 week or rises after retreating. Before relaxation, there is chill, incision. The pain is intensified. Finally, the shortest time in the local incision or drainage is 3D after surgery. The elderly are more than 2 weeks, usually about 7 days. Physical examination, pressing the incision, there is tenderness at the edge of the sternum, such as mediastinal infection has spread to the bone marrow. Inflammation, the sternum begins to be unstable, there are some signs of sternal opening, blood tests, white blood cell count and multinucleated cells are significantly increased, the count can be increased to (10 ~ 20) × 10 ⁹ / L (1000 ~ 2000 / mm ³ ) There are up to 30×10 ⁹ /L (3000/mm ³ ) or more; multinucleated cells are often more than 90%, and the lateral sternal radiograph shows a darkening shadow behind the sternum. If osteomyelitis is still showing osteoporosis And destruction.

Secondary mediastinal infection

The examination of this disease mainly relies on X-ray and CT examination.

X-ray films could not detect abnormalities in the early stage. When a congenital granuloma-type mediastinal infection was found, local mediastinum was widened on the X-ray film. The most common X-ray showed prominent right paratracheal mass and increased density of the posterior sternal space. The lesion is composed of granuloma mass, inflammatory lymph, mixed with fibrous tissue, and similar mass in the subcarinal area is most visible in the lateral position and oblique letter. For example, the mediastinal space after infection and invasion, the esophageal tract is visible. The marginal edge is not complete. Observing the subcarinal mass from the posterior anterior chest radiograph is only the increase in the density of the upper part of the heart shadow. The large mass causes the bilateral main bronchus to be displaced, and the bifurcation angle of the tracheal carina is widened. The contour of the mass is not very clear. If the center of the tumor is necrotic or dry, it is easy to be calcified, and the contour of the calcification is irregular. Tomography (CT) can show that the localized fibrous variant X-ray diagnosis, with X-ray image of an organ in the mediastinum. To highlight, the most common one is the widening of the right superior mediastinum of the superior vena cava syndrome.

Diagnosis and diagnosis of secondary mediastinal infection

Diagnosis can be based on medical history, clinical symptoms, and laboratory tests.

Differential diagnosis

Need to be differentiated from primary mediastinal tumors, because when the tumor occurs in the mediastinum, it is easy to merge infection, and strict distinction is needed to avoid delay in treatment.

The main symptoms of mediastinal tumors are as follows:

(1) respiratory symptoms: chest tightness, chest pain usually occurs in the back of the sternum or the side of the chest, most malignant tumors invade the bones or nerves, the pain is severe, cough is often caused by pressure of the trachea or lung tissue, hemoptysis is less common.

(2) symptoms of the nervous system: due to tumor compression or erosion of the nerve to produce various symptoms: such as tumor invasion can cause hoarseness, can produce chest pain or paresthesia, causing limb paralysis.

(3) Symptoms of infection: If the cyst is broken or the tumor infection affects the bronchial or lung tissue, a series of infection symptoms appear.

(4) symptoms of compression: esophagus, tracheal compression, there may be symptoms such as shortness of breath or hypopharyngeal obstruction.

(5) Special symptoms: The patient coughs up sebum and hair.

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