Pneumomediastinum is air in the mediastinum. The mediastinum is the space in the middle of the chest, between the lungs.
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:
It may also happen after:
Pneumomediastinum also can occur with pneumothorax or other diseases.
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.
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.
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.
The outlook depends on the disease or events that caused the pneumomediastinum.
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.
Go to the emergency room or call the local emergency number (such as 911) if you have severe chest pain or difficulty breathing.
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.
Celli BR. Diseases of the diaphragm, chest wall, pleura, and mediastinum. In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 99.