What is pneumomediastinum

Pneumomediastinum is an uncommon and usually self-limited condition where there is air in the mediastinum ¹. The mediastinum is the space in the middle of the chest, between the lungs and around the heart. The air or gas may originate from the lungs, trachea, central bronchi, esophagus, and peritoneal cavity and track from the mediastinum to the neck or abdomen.

Spontaneous pneumomediastinum is an uncommon condition presenting in approximately one in 1,000 to one in 40,000 emergency department referrals ². Young patients with spontaneous pneumomediastinum typically present with a history of asthma or recent inhalation of cocaine, methamphetamine, ecstasy, marijuana or hydrocarbons ³. Other causes include barotrauma in asthmatics and chronic obstructive pulmonary disease (COPD) patients, rapid ascent in scuba divers, valsalva maneuvers, vomiting, infections, blast injuries and iatrogenic injuries from endoscopy or surgery ⁴. The most common presentation is nonspecific pleuritic chest pain with dyspnea. Potential life-threatening causes include esophageal rupture and tension pneumothorax, but these are historically evident at presentation ⁵. Because a subset of patients with this finding have significant pathology, extensive workups are often necessary. Treatment is generally limited to observation, with the spontaneous pneumomediastinum typically reabsorbing over a period of one to two weeks without intervention and only rare recurrence ⁶.

Pneumomediastinum causes

Pneumomediastinum 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:

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

Pneumomediastinum may also happen after:

• An infection in the neck or center of the chest
• Rapid rises in altitude, or scuba diving
• Tearing of the esophagus (the tube that connects the mouth and stomach)
• Tearing of the trachea (windpipe)
• Use of a breathing machine
• Use of inhaled recreational drugs, such as marijuana or crack cocaine
• Surgery

Pneumomediastinum also can occur with collapsed lung (pneumothorax) or other diseases.

Although it is rare, pneumomediastinum can occur spontaneously. This is considered benign and generally affects young adult males ⁷.

Pneumomediastinum symptoms

There may be no symptoms. Pneumomediastinum 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.

Pneumomediastinum possible complications

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

In rare cases, air may enter the area between the heart and the thin sac that surrounds the heart. This condition 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, so they cannot work properly.

All of these complications require urgent attention because they can be life threatening.

Pneumomediastinum diagnosis

During a physical examination, the health care provider 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. This is to confirm that air is in the mediastinum, and to help diagnose a hole in the trachea or esophagus.

Pneumomediastinum treatment

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

Your doctor may put in a chest tube if you also have a collapsed lung. You may also need treatment for the cause of the problem. A hole in the trachea or esophagus needs to be repaired with surgery.

Pneumomediastinum prognosis

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

References

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2. Newcomb AE. Chest. 2005;128:3298–3302
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5. Henderson JAM, Peloquin AJM. Boerhaave revisited: spontaneous esophageal perforation as a diagnostic masquerader. Am J Med. 1989;86:559–567.
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7. Jougon JB, Ballester M, Delcambre F, Mac Bride T, Dromer CE, Velly JF. Assessment of spontaneous pneumomediastinum: experience with 12 patients. The Annals of thoracic surgery. 75 (6): 1711-4.