Pneumomediastinum: Symptoms, Causes, and Clinical Management
Updated: 2 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: September 2026
Pneumomediastinum, also called mediastinal emphysema, is the term for air trapped in the mediastinum — the central compartment of the chest that houses the heart, esophagus, and trachea, sitting between the two lungs. It sounds alarming, and sometimes it is, but most cases are spontaneous and resolve on their own within days. This guide walks through what causes it, how it's recognized, and when it signals something more serious.
Spontaneous vs. Secondary: Two Very Different Pictures
Doctors sort pneumomediastinum into two categories, and the distinction matters for how urgently it needs treatment.
Spontaneous (SPM): Occurs without any obvious injury or illness — the cause may never be identified. It affects roughly 1 in 25,000 people, most often between ages 5 and 34, and is generally not considered a medical emergency.
Secondary: Develops as a direct result of trauma, surgery, or a serious underlying illness. This form requires immediate medical evaluation.
Recognizing the Symptoms
Some people have no symptoms at all — the finding turns up incidentally on imaging done for something else. When symptoms do appear, they tend to cluster around three areas:
Chest pain: Severe pain centered in the middle of the chest or breastbone that can radiate to the neck or arms, and often worsens with breathing or swallowing.
Respiratory issues: Shortness of breath, particularly in secondary cases.
Physical changes: Swelling in the face or neck, a high-pitched or distorted voice, and subcutaneous emphysema — small air pockets trapped under the skin that feel “crunchy” to the touch.
What Causes It
Pneumomediastinum happens when air escapes from the trachea, bronchi, alveoli, or esophagus and migrates into the mediastinal space — usually driven by a sudden spike in pressure inside the chest.
Physical strain: Forceful coughing, sneezing, vomiting, or bearing down during childbirth or a bowel movement can raise chest pressure enough to cause a leak.
Trauma and surgery: Blunt chest injury or recent surgery involving the neck, chest, or abdomen is a leading cause of secondary cases.
Underlying illness: Lung diseases such as asthma and COPD, or bacterial, fungal, or viral infections, can weaken lung structures enough to let air escape.
External factors: Scuba diving, mechanical ventilation, and inhaled recreational drug use are recognized triggers.
Smokers and people with pre-existing respiratory conditions face a higher risk, as do those who've recently had chest surgery or trauma.
How It's Diagnosed
Diagnosis starts with a physical exam. One classic clue is Hamman's sign — a crunching sound, timed with the heartbeat, heard through a stethoscope. Confirming the diagnosis and gauging how much air has built up requires imaging: a chest X-ray or CT scan.
Treatment: Mostly Watching and Waiting
In most cases, the trapped air doesn't need direct treatment — the body reabsorbs it on its own. Management instead centers on observation and treating whatever caused it:
Monitoring: Patients are typically admitted for at least 24 hours to confirm the condition isn't worsening.
Supportive care: Oxygen therapy can speed up reabsorption, while pain relievers and cough suppressants manage symptoms.
Specialized intervention: In rare severe cases where air pressure threatens the heart or major vessels, needle aspiration or a drain may be necessary.
Possible Complications and Outlook
Pneumomediastinum is rarely fatal by itself, but when the underlying cause is severe, complications can follow:
Pneumothorax: A buildup of air that leads to a collapsed lung.
Pneumopericardium: Air moving into the sac around the heart, which can affect its function.
Pressure on blood vessels: Excess air can compress major vessels and interfere with circulation.
The outlook for spontaneous cases is excellent — most people recover fully within a week. For secondary cases, the prognosis tracks the severity of whatever caused it, and care often involves a multidisciplinary team spanning emergency medicine, radiology, and pulmonology.
Frequently Asked Questions
What is the difference between pneumomediastinum and a collapsed lung? Pneumomediastinum involves air in the space between the lungs, whereas a collapsed lung (pneumothorax) occurs when air enters the space between the lung and the chest wall.
Is pneumomediastinum life-threatening? The condition itself is usually not fatal, but the underlying causes, such as a ruptured organ, can be life-threatening.
Can I have pneumomediastinum without knowing it? Yes — some people are asymptomatic, and it's only discovered incidentally during imaging for other issues.
How is the “crunching” sound diagnosed? A healthcare provider listens for Hamman's sign, a sound timed with the heartbeat, using a stethoscope.
How long does recovery take? Spontaneous cases typically resolve within three days to a week.
Can coughing cause this condition? Yes, severe or excessive coughing can raise chest pressure enough to cause spontaneous pneumomediastinum.
Is surgery required for treatment? Surgery is rarely needed for the air itself, but may be required to repair an underlying organ injury.
What is subcutaneous emphysema? It's the presence of air pockets under the skin, often felt as a crunchy texture in the neck or face.
Can smoking increase my risk? Yes, smoking is a significant risk factor because it can damage lung tissue.
Is oxygen therapy always necessary? No, but it can help the body absorb the trapped air more quickly.
Can childbirth cause pneumomediastinum? Yes — the intense pressure during pushing can sometimes lead to the condition.
What imaging is best for diagnosis? Chest X-rays and CT scans are the standard tools for visualizing air in the mediastinum.
Will the condition come back? Spontaneous cases rarely recur once resolved. Recurrence in secondary cases depends on the underlying health issue.
Are children at risk? Yes, the condition is most common in people aged 5 to 34.
When should I go to the emergency room? Seek immediate care for chest pain, shortness of breath, or severe swelling.
Related Reading
If you experience sudden chest pain or unexplained swelling in the neck or face, contact a healthcare professional immediately for a comprehensive evaluation.
This content is for informational purposes only and does not constitute medical advice. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition or treatment.
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