What Is Mediastinal Emphysema?

Mediastinal emphysema refers to the fact that air enters between the connective tissue spaces in the pleura of the mediastinum for various reasons. It can be spontaneous, chest trauma, esophageal perforation, and iatrogenic factors.

Basic Information

English name: mediastinal emphysema
Visiting department: Thoracic Surgery

Common locations: Mediastinum
Common causes: Spontaneous, chest trauma, esophageal perforation, iatrogenic factors, etc.
Common symptoms: Chest tightness, shortness of breath, pain behind the sternum

Causes of mediastinal emphysema

1. Alveolar rupture, the air enters the mediastinum along the sheath around the pulmonary blood vessels. There are often incentives to hold your breath after inhalation, hard cough and other inducements. It is found in bronchial asthma, bronchiolitis, pertussis and other diseases. Spontaneous pneumothorax caused by alveolar rupture can also occur with mediastinal emphysema.

2. In the treatment of respiratory distress, positive end-expiratory pressure is used for breathing. Excessive pressure can easily cause barotrauma to the lungs and spontaneous pneumothorax and / or mediastinal emphysema.

3. Chest trauma, endoscopy or inhalation of foreign bodies can cause bronchial or esophageal rupture and mediastinal emphysema. Esophageal spasm is obstructed, and longitudinal tears often occur 8 cm below the esophagus, because there is no connective tissue support in the esophagus. Esophageal rupture is often accompanied by pleural effusion or empyema.

4. Neck surgery, such as thyroidectomy or tonsillectomy, sometimes gas can enter the mediastinum along the deep fascia of the neck. In tracheotomy, if the skin incision is too small and the trachea incision is too large, the escape of air is prone to mediastinal emphysema.

5. Gastrointestinal perforation, peri-renal inflatable angiography or artificial pneumoperitoneum, the gas in the abdominal cavity can enter the mediastinum through the loose tissue around the diaphragm aorta and the esophagus.

Clinical manifestations of mediastinal emphysema

1. History and symptoms

Note the related causes and medical history of this disease, a small amount of gas accumulation in the mediastinum may be asymptomatic, and generally may have chest tightness, shortness of breath, and pain behind the sternum. Such as the sudden occurrence of mediastinum to a large amount of gas and tension pneumothorax, severe chest pain, dyspnea, palpitations, increased heart rate, high fever, chills, shock during infection. Severe mediastinal emphysema compresses large blood vessels in the chest, affecting blood volume and circulatory disturbances.

2. Signs

For example, when there is subcutaneous emphysema on the neck, upper sternal bone, or chest axillary, and abdomen, there is a feeling of snow under the skin, twisting the sound; hypervoicing behind the sternum, shrinking or disappearing of the heart dullness, and a special heartbeat can be heard in front of the heart. Friction (click). In severe cases, chest and neck venous reflux disorders, varicose veins, and hypotension. The patients with pneumothorax showed drum sounds on the percussion side, and the breathing sounds disappeared.

Mediastinal emphysema

There is no relevant laboratory inspection data.

Chest X-ray examination is decisive for the diagnosis of mediastinal emphysema. On the posterior anterior chest radiograph, the mediastinal pleura is shifted to both sides, forming a high-density linear shadow parallel to the mediastinal contour. The gas-transparent shadow between the medial and mediastinal contour is usually obvious on the upper mediastinum and the left edge of the mediastinum The above signs should be distinguished from the normal translucent narrow translucent bands. The main point of identification is that there is no high-density mediastinal pleura on the outside of the Mach band. In addition, some patients can still find air translucent bands next to the thoracic aorta or the pulmonary arteries. Infants can show thymus outlines when there is a large amount of gas in the mediastinum. Mediastinal emphysema appears on the lateral chest radiograph as a widened area with increased transillumination behind the sternum, moving the mediastinal pleura back to a line-shaped shadow, and increasing the distance between the heart and the leading edge of the ascending aorta and the sternum. X-ray examination can also clearly show coexisting pneumothorax and subcutaneous emphysema of the lower neck and chest.

Chest CT examination: Because the chest CT is not affected by organ overlap, it shows the mediastinal emphysema more clearly, especially when there is less gas accumulation in the mediastinum, and the posterior anterior chest radiograph is easy to identify.

Mediastinal emphysema diagnosis

Chest X-ray examination: The posterior anterior chest X-ray showed that the mediastinal pleura was pushed to both sides by gas, and band-shaped translucent shadows were visible on both sides of the mediastinum. Patients with subcutaneous emphysema see air bands under the skin of the neck and chest, signs of gas accumulation.

Differential diagnosis of mediastinal emphysema

The disease in the mediastinum should be distinguished from the pericardial gas. The volume of gas in the pericardium is lateral when it is in the supine position. The posterior anterior chest radiograph shows the pericardial reflexed dome at the root of the heart. The gas in the outer mediastinum emphysema is located on both sides of the upper mediastinum.

Mediastinal Emphysema Treatment

General treatment

Most patients with mild mediastinal emphysema are usually treated with bed rest, antibiotics, analgesia, and oxygen inhalation. The gas absorption is cured within a week. A few patients fast and give parenteral nutrition.

2. Local exhaust treatment

For those who have more mediastinal gas accumulation and compression symptoms, who still can't get better after general treatment, can perform incision drainage drainage decompression under local anesthesia on the sternal notch. Those with subcutaneous emphysema can also make an upper chest skin incision and squeeze the air out.

3. Primary disease treatment

Traumatic drainage and tension-induced pneumothorax are used for closed drainage, repair and suture of broken trachea, leaked esophagus, etc., and comprehensive treatment of the primary tumor.