Pneumomediastinum refers to the presence of trapped air in the center of your chest. The area between the lungs is called the mediastinum.

The mediastinum contains:

Primary or spontaneous pneumomediastinum refers to a form of the condition with no obvious cause. Secondary pneumomediastinum is most often caused by injury or trauma, which can cause air leakage from the lungs or digestive tract.

We’ll go over different ways air gets into the mediastinum, what symptoms you may experience, and treatment options.

The main symptom of pneumomediastinum is chest pain. This can come on suddenly and may be severe.

Other symptoms include:

Air from the mediastinum can move under the skin of the chest, face, or neck. This is called subcutaneous emphysema. It often looks like a smooth bulge under your skin and can cause pain and swelling.

Your doctor might hear a crunching sound in time with your heartbeat when listening to your chest with a stethoscope. This is called Hamman’s sign, or “mediastinal crunch.”

A differential diagnosis

The symptoms of pneumomediastinum can look similar to an esophageal perforation, when a hole develops in your esophagus. The esophagus is a tube that transports food and liquid from your mouth to your stomach.

Fluid leaking from this tear can also get stuck in the mediastinum, and most cases require surgery to repair the hole. Doctors use CT scans and X-rays to identify or rule out this condition.

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Pneumomediastinum can happen when pressure rises in the lungs and causes the air sacs (alveoli) to rupture. It can also occur as a result of damage to the lungs or nearby structures, which then allow air to leak into the center of the chest.

The condition is usually not life threatening and often goes away on its own or with conservative, or noninvasive, treatment.

However, you should always seek medical care when experiencing chest pain and trouble breathing. Pneumomediastinum should be evaluated at a hospital and may require an overnight stay.

Primary pneumomediastinum

Also called spontaneous pneumomediastinum (SPM), this form of the condition doesn‘t result from obvious trauma to the mediastinum or nearby areas. “Spontaneous” refers to its sudden appearance in previously healthy people.

However, certain underlying health conditions or events can raise the pressure inside the lungs and begin the process that leads to SPM.

Smoking and drug use are central risk factors for developing SPM. A 2013 research review explained that spontaneous pneumomediastinum is “often seen in young males who are smokers” or in people with a preexisting lung condition. Asthma and a history of respiratory infections were also associated with SPM.

A 2016 study also noted the condition mostly affected young adult males, and most people with SPM make a full recovery with conservative treatment.

In very rare instances, some COVID-19 patients have developed spontaneous pneumomediastinum due to respiratory tract inflammation.

Secondary pneumomediastinum

Secondary pneumomediastinum has a known or traceable cause. Usually, this is an injury to the mediastinum due to an accident, a medical procedure, or an underlying health condition.

Main causes of secondary pneumomediastinum include:

Other causes may include:

  • experiencing a sudden change in air pressure, such as while scuba diving or skydiving
  • performing the Valsalva maneuver (blowing hard while you’re bearing down, a technique used to pop your ears)
  • using a breathing machine, such as a ventilator

Certain factors make you more likely to experience pneumomediastinum.

These include:

  • Gender. People assigned male at birth make up most cases of pneumomediastinum.
  • Lung disease. Pneumomediastinum is more common in people with asthma and other lung diseases.
  • Smoking or tobacco use. This damages lung tissue and function over time.

Two imaging tests are used to diagnose pneumomediastinum:

  • CT scan. A CT scan uses X-rays to create detailed pictures of your lungs. It can show whether air is in the mediastinum.
  • X-ray. An X-ray uses small doses of radiation to make pictures of your lungs. It can help find the cause of the air leak.

These tests can check for a tear in your esophagus or lungs:

  • An esophagogram is an X-ray of the esophagus that’s taken after you swallow barium.
  • An esophagoscopy passes a tube down your mouth or nose to view your esophagus.

Pneumomediastinum usually isn’t life threatening. The stuck air will eventually reabsorb into your body. The main goal in treating pneumomediastinum is to manage your symptoms and uncover any possible underlying health conditions.

Most people experiencing pneumomediastinum will stay overnight in the hospital for monitoring.

After that, treatment usually consists of conservative approaches, such as:

Some people may need oxygen to help them breathe. Oxygen can also speed up the reabsorption of air in the mediastinum.

Any underlying condition that might have caused the air buildup, such as asthma or a lung infection, will need to be treated. Your doctor may order other labs or imaging tests to investigate.

Pneumomediastinum sometimes happens together with pneumothorax, a buildup of air in the cavity outside the lungs.

Pneumomediastinum and pneumothorax usually both involve chest pain and breathing changes. However, pneumothorax has some unique symptoms.

These include:

If enough air collects and puts pressure on a lung, it can collapse. In this case, doctors may have to extract the air by inserting a needle or tube into your chest cavity. Pneumothorax doesn‘t always lead to a collapsed lung.

Serious pneumomediastinum in newborns and young children is very rare. But mild, temporary spontaneous pneumomediastinum in newborns happens more frequently. Many experts believe the condition is underdiagnosed, as many babies display no symptoms, and the condition may resolve on its own.

Pneumomediastinum is more common in babies who:

Others have symptoms of breathing distress, including:

  • abnormally fast breathing
  • grunting
  • flaring of the nostrils

Babies with symptoms will receive oxygen to help them breathe. If an infection is identified as the cause of pneumomediastinum, doctors will treat it with antibiotics. Babies are carefully monitored afterward to make sure all the air dissipates.

Pneumomediastinum refers to trapped air in your chest and can happen due to an accident, medical procedure, or unknown cause. It affects people of all ages, but males are more likely to experience it.

Most types of pneumomediastinum resolve with rest and conservative treatment but may require a short stay in the hospital. The majority of patients fully recover with no long-term complications. Recurring pneumomediastinum is rare, but it can occur as a result of a chronic condition (like asthma) or ongoing drug use.

Always contact a doctor if you‘re experiencing chest pain and trouble breathing. Pneumomediastinum can occur on its own or be a sign of an underlying health issue. It‘s important to be promptly evaluated so you can get the care you need.