Pneumomediastinum is air in the chest cavity (mediastinum).
The mediastinum, located in the central part of the chest (see Overview of Pleural and Mediastinal Disorders), can become filled with air when the small air sacs of the lungs (alveoli) become stretched and torn, the esophagus rips or tears, or the intestine tears causing air to leak into the chest cavity.
Most often, people have chest pain below the breastbone. The pain may be severe.
Doctors do a physical examination. They may hear a crunching or crackling noise when they listen to the chest through a stethoscope. A chest x-ray is done to confirm the diagnosis.
Usually, treatment is not necessary. However, the problem that caused pneumomediastinum may require treatment.
Last full review/revision November 2012 by Richard W. Light, MD