Pneumomediastinum

Definition

Pneumomediastinum is air in the mediastinum. The mediastinum is the space in the middle of the chest, between the lungs.

Alternative Names

Mediastinal emphysema

Causes, incidence, and risk factors

Pneumomediastinum is uncommon. The condition can be caused by injury or disease. Most often, it occurs when air leaks from any part of the lung or airways into the mediastinum.

Increased pressure in the lungs or airways may be caused by:

• Excessive coughing
• Repeated bearing down to increase abdominal pressure (such as pushing during childbirth or a bowel movement)
• Sneezing
• Vomiting

It may also happen after:

• Rapid rises in altitude, SCUBA diving
• Tearing of the esophagus (the tube that connects the mouth and stomach)
• Tearing of the trachea (windpipe)
• Use of a breathing machine
• Using inhaled recreational drugs such as crack cocaine

Pneumomediastinum also can occur with pneumothorax or other diseases.

Symptoms

There may be no symptoms. The condition usually causes chest pain behind the breastbone, which may spread to the neck or arms. The pain may be worse when you take a breath or swallow.

Signs and tests

During a physical examination, the doctor may feel small bubbles of air under the skin of the chest, arms, or neck. A chest x-ray or CT scan of the chest may be done to confirm that there is air in the mediastinum, and help diagnose a hole in the trachea or esophagus.

Treatment

Often, no treatment is needed because the body will gradually absorb the air. Breathing high concentrations of oxygen may speed up this process.

The doctor may put in a chest tube if you also have a collapsed lung (pneumothorax). Surgery is needed to repair a hole in the trachea or esophagus.

Support Groups

Expectations (prognosis)

The outlook depends on the disease or events that caused the pneumomediastinum.

Complications

The air may build up and enter the space around the lungs (pleural space), causing the lung to collapse.

More rarely, air may enter the area between the heart and the thin sac that surrounds the heart. This is called a pneumopericardium.

In other rare cases, so much air builds up in the middle of the chest that it pushes on the heart and the great blood vessels, making them unable to work properly.

All of these complications require urgent attention.

Calling your health care provider

Go to the emergency room or call the local emergency number (such as 911) if you have severe chest pain or difficulty breathing.

Prevention

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References

Park DR, Vallieres E. Pneumomediastinum and mediastinitis. In: Mason RJ, Broaddus VC, Martin TR, et al, eds. Textbook of Respiratory Medicine. 5th ed. Philadelphia, Pa: Saunders Elsevier; 2010: chap 77.