Pneumomediastinum is the abnormal presence of air or another gas in the mediastinum. The mediastinum is the center of the chest and is located between the lungs.
Air can get stuck in this area because of trauma or leakage from the lungs or windpipe. It is known as spontaneous pneumomediastinum when there is no apparent cause. The condition is rare and accounts for between 1 in 7,000 and 1 in 45,000 cases of hospital admittance.
Read on to learn more about the symptoms and treatment of pneumomediastinum.
The main symptom is normally a severe pain in the center of the chest. Other symptoms can include:
- air under the skin on the chest, known as subcutaneous emphysema
- changes in the voice
- difficulty swallowing, known as dysphagia
- labored breathing
- neck pain
- shortness of breath
A doctor, listening to the chest of someone with a pneumomediastinum, may hear a crunching noise that is in time with the heartbeat. This sound is known as Hamman’s crunch.
The mediastinum may fill with air due to:
- injury to the neck or chest
- surgery on the neck, chest, or abdomen
- asthma or other conditions that cause forceful coughing
- chest infections and lung diseases, such as COPD and interstitial lung disease
- difficult childbirth
- excessive vomiting
- inhalation of toxic fumes
- intense exercise
- rapid changes in air pressure while diving
- use of recreational drugs, such as cocaine and methamphetamine
- use of a ventilator
The Valsalva maneuver may also cause a pneumomediastinum. This maneuver involves forcefully exhaling against a closed airway. The Valsalva maneuver is commonly done to pop the ears.
Factors that increase the likelihood of a pneumomediastinum include:
- Age: Babies and children may be at greater risk of the condition than adults because their chest tissues are less stiff, resulting in an easier path for air movement.
- Sex: Approximately 76 percent of cases affect males, especially young males.
- Lung health: People with lung diseases, including asthma, bronchiectasis, cystic fibrosis, COPD, interstitial lung disease, and cysts, are at higher risk of the condition.
A doctor will take a medical history and perform a physical examination to diagnose pneumomediastinum. They will probably listen to the chest with a stethoscope.
Imaging tests are usually required to see the lungs, airways, and mediastinum. They may include:
- Chest X-ray: This test takes pictures of the chest and upper abdominal organs to look for the underlying cause of the air leakage.
- CT scan: A CT scan takes a detailed image of the chest so a doctor can check for air in the mediastinum. The scan can show the extent of the pneumomediastinum or confirm cases when a chest X-ray is inconclusive.
- Ultrasound: This test uses sound waves to look for air outside the lungs. It can provide instant results and does not use X-rays. A medical gel is placed on the skin so that the ultrasound wand can visualize structures inside the chest cavity.
Other less commonly used tests may be done to identify or confirm an underlying medical condition. These include:
- Bronchoscopy: This procedure examines the airways of the lungs, using a thin tube fitted with a light and camera. The tube is inserted through the nose or mouth until it enters the bronchi and small airways of the lungs.
- Endoscopy: During this procedure, a tube is passed down the throat or nose into the esophagus, stomach, or upper intestine.
- Esophagogram: This test involves someone drinking material that contains barium to coat their esophagus. An X-ray is taken to see the outline of the esophagus and upper digestive tract.
Pneumomediastinum is rarely serious and will usually resolve on its own. Treatment is aimed at managing symptoms and any underlying cause.
Most people will spend at least 24 hours in a hospital for observation. Recommended treatments include:
- bed rest
- avoidance of physical activity
- anti-anxiety medication
- cough remedies
- oxygen to aid breathing and encourage absorption of the trapped air
- pain-relieving drugs
If a lung condition is contributing to pneumomediastinum, that condition will typically require treatment. Doctors may prescribe antibiotics for infections or breathing treatments for asthma, for example.
Spontaneous pneumomediastinum usually resolves without treatment, although it has been known to persist for over 2 months in some cases.
Treatment also includes dealing with complications such as pneumothorax, also known as a collapsed lung.
Pneumothorax results from the buildup of air between the lungs and wall of the chest. People with a collapsed lung may require the insertion of a chest tube to release the air and allow the lung to re-inflate.
Complications can also affect the heart. Rarely, a pneumomediastinum can lead to air accumulating around the sack of the heart, making it difficult for the heart to beat normally.
Pneumomediastinum may affect approximately 2 in every 1,000 births. Its occurrence is, however, probably underestimated because it does not always cause symptoms that lead to 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 (aspirate) their first feces during birth
- have urgent or emergency situations during birth
If a newborn has symptoms they can include:
- flaring nostrils
- unusually fast breathing
- trouble sucking
- enlargement of the chest
A baby will receive oxygen to help them breathe and encourage reabsorption of air if they show symptoms of breathing distress. Antibiotics and other treatments will be prescribed for any other underlying problems.
It is often necessary to monitor the newborn in the neonatal intensive care unit or NICU while the pneumomediastinum is treated.
Pneumomediastinum is not usually a cause for concern and typically has a good outlook. Some symptoms, such as pain and breathing difficulties, can, however, cause distress. Treatments are aimed at minimizing these symptoms until the air in the chest dissipates.
Follow-ups after the pneumomediastinum has resolved is not usually required because the condition is unlikely to reoccur. Recurrent cases, however, have been reported, especially where drug use or lung illness are involved