Pneumomediastinum is the abnormal presence of air in the mediastinum, which is the space between the lungs and surrounding the heart. Air may enter the mediastinum from a leakage in a lung, the esophagus, or airways.

Pneumomediastinum is uncommon. While most cases resolve without treatment, some can cause serious and potentially life threatening complications. As such, it is important that people are able to identify symptoms that require prompt medical attention.

This article describes what pneumomediastinum is, including its symptoms, causes, and risk factors. We also provide information on how doctors diagnose and treat pneumomediastinum and its complications in adults as well as newborns.

Finally, we answer some frequently asked questions about the condition.

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Pneumomediastinum is the medical term for the abnormal presence of air within the mediastinum. The mediastinum is the space in the center of the chest, between the lungs and surrounding the heart.

It is an uncommon condition. Instances are typically due to air leaking from a lung, airway, or the esophagus into the mediastinum.

In some cases, pneumomediastinum may not cause any symptoms. In other cases, a person can experience pain behind the breastbone. The pain may radiate to the neck or arms and can worsen when a person inhales or swallows.

Other possible symptoms of pneumomediastinum include:

A doctor who is listening to the chest of someone with pneumomediastinum may hear a crunching noise that is in time with the heartbeat. Medical professionals refer to this as “Hamman’s crunch.” The sound is due to the heart beating against tissues that are full of air.

Pneumomediastinum occurs as a result of air leaking from a lung, esophagus, or airway into the mediastinum. This may occur due to the following:

  • infection or injury to the neck or chest
  • tearing of the esophagus or windpipe
  • surgery on the neck, chest, or abdomen
  • sneezing
  • forceful coughing due to asthma or other respiratory conditions
  • Valsalva maneuver, which involves forcefully exhaling against a closed airway, such as when attempting to pop the ears
  • repeated bearing down, such as during a bowel movement or childbirth
  • chest infections and lung diseases, such as chronic obstructive pulmonary disease (COPD) and interstitial lung disease
  • inhaling toxic fumes
  • excessive vomiting
  • intense exercise
  • rapid changes in air pressure while diving
  • inhaling recreational drugs, such as marijuana or crack cocaine
  • using a ventilator

Factors that increase the likelihood of a pneumomediastinum include:

  • Age: Compared with adults, babies and children may be at increased risk of pneumomediastinum. This is because their chest tissues are more flexible, allowing an easier path for air movement.
  • Sex: Approximately 76% of pneumomediastinum cases affect males, especially young males.
  • Lung health: People with existing respiratory diseases are at increased risk of pneumomediastinum. Examples of such diseases include:

To diagnose pneumomediastinum, a doctor will take a medical history and perform a physical examination. The latter will involve listening to the chest with a stethoscope.

A doctor may also order one of the following imaging tests to check the lungs, airways, and mediastinum:

  • Chest X-ray: This test uses X-rays to create images of the chest and upper abdominal organs. It can help detect the presence of air and diagnose the condition.
  • CT scan: A CT scan combines multiple X-ray images to form a detailed image of the chest. The scan can show the presence or extent of the pneumomediastinum or confirm cases when a chest X-ray is inconclusive.
  • Ultrasound scan: This test uses sound waves to check for air outside the lungs. It can provide instant results and does not use X-rays.

Other tests can sometimes help to identify or confirm pneumomediastinum and its underlying cause. These include:

  • Bronchoscopy: This procedure examines the airways within the lungs using a thin tube that has a light and camera. A surgeon inserts the tube through the nose or mouth and into the bronchi and small airways of the lungs.
  • Endoscopy: This imaging technique involves passing a thin tube, or “endoscope,” down the throat or nose into the esophagus, stomach, or upper intestine. The endoscope contains a light and camera.
  • Esophagogram: This test involves drinking a liquid containing barium sulfate, which makes the esophagus and upper digestive tract more visible on an X-ray.

Pneumomediastinum is rarely serious and usually resolves on its own as the body gradually reabsorbs the air in the mediastinum.

Some general treatments that may help to alleviate symptoms and speed up healing include:

  • bed rest
  • avoidance of physical activity
  • cough remedies
  • pain-relieving drugs
  • oxygen to aid breathing and encourage the absorption of trapped air

In some cases, a person may require treatment for the underlying cause of the pneumomediastinum. For example, doctors can prescribe antibiotics for infections or breathing treatments for asthma.

Complications

Treatment also includes dealing with pneumomediastinum complications, such as pneumothorax and pneumopericardium.

Pneumothorax is the medical term for a collapsed lung. It occurs due to the buildup of air between the inner and outer linings of the lung.

The treatment for pneumothorax involves inserting a tube into the chest to release the trapped air, which allows the lung to reinflate.

Pneumopericardium is the medical term for an accumulation of air between the inner and outer lining of the pericardium, which is the membrane surrounding the heart. Air in this area makes it difficult for the heart to beat normally.

The treatment for pneumopericardium involves draining the air with a needle.

Pneumomediastinum occurs in approximately 2.5 out of every 1,000 live births. However, the exact number may be higher, since the condition does not always cause symptoms that prompt a diagnosis.

It is more likely to occur in newborns who:

  • need a mechanical ventilator to aid breathing
  • develop a lung infection, such as pneumonia
  • breathe in or “aspirate” their first feces during birth
  • require emergency care during birth

If a newborn develops symptoms of pneumomediastinum, these may include:

A baby who develops pneumomediastinum will typically require monitoring and treatment in a neonatal intensive care unit (NICU).

Babies who show signs of breathing difficulty will receive oxygen to help them breathe and to help their body reabsorb the air in the mediastinum.

A doctor may also prescribe treatment for the underlying cause of the pneumomediastinum, such as antibiotics to help combat bacterial infection.

Below, we answer some commonly asked questions about pneumomediastinum.

How long does it last?

Pneumomediastinum resolves when the body has finished reabsorbing the air in the mediastinum. The rate of reabsorption may differ from person to person and can depend on certain factors, such as:

  • the underlying cause of the pneumomediastinum
  • whether the cause required treatment, and whether the treatment was effective
  • whether the person has received oxygen therapy
  • the person’s overall health

Most cases of pneumomediastinum resolve in under 2 months.

Can it cause pneumothorax?

Pneumothorax is a possible complication of pneumomediastinum. This is because the trapped air in the mediastinum can accumulate in the pleural space around the lungs, causing one or both lungs to collapse.

A collapsed lung may be minor or severe. Possible symptoms include:

Anyone who experiences severe or worsening symptoms of a collapsed lung should seek emergency medical attention.

Is it life threatening?

In rare cases, pneumomediastinum may cause a potentially life threatening condition called pneumopericardium, in which air enters the space between the heart and the pericardium.

A large accumulation of air in the center of the chest may also push against the heart and major blood vessels to the extent that these tissues cannot function properly.

Anyone who experiences persistent or worsening chest pain or other concerning symptoms should seek prompt medical attention.

Pneumomediastinum is the medical term for the abnormal presence of air in the mediastinum, which is the space between the lungs and surrounding the heart. The condition is due to air leaking from a lung, airway, or the esophagus and into the mediastinum.

Symptoms do not always occur but may include chest pain and breathing difficulties.

Pneumomediastinum is not usually a cause for concern and typically goes away without medical treatment once the body has reabsorbed the air from the mediastinum. Oxygen therapy and other treatments can help to speed up the process while alleviating symptoms.

In rare cases, pneumomediastinum can cause serious and potentially life threatening complications, such as pneumothorax and pneumopericardium. Anyone who experiences persistent or worsening chest pain or breathing difficulties should seek emergency medical attention.