Collapsed Lung (Pneumothorax)

Collapsed lung, also known as pneumothorax, occurs when the space between the lung and the chest wall fills up with air, affecting the quality of breathing. Sometimes the condition can be serious enough to cause death.

What Is Collapsed Lung?

A collapsed lung occurs when air or other gas fills the space surrounding the lung, called the pleural (PLU-ral) cavity. The buildup of air in the space puts pressure on the lung so that the lung cannot expand and contract with breathing, making it difficult for the person to breathe. The medical term for this condition is pneumothorax (NU-mo-THO-raks), which means that air (pneuma in Greek) is in the chest (thorax). A related condition that can occur as a result of severe injury to the chest is hemothorax (HE-mo-THO-raks), which means that blood (haima in Greek) is in the chest (thorax).

How Common Is Collapsed Lung?

Collapsed lung is not very common. There are between 7.4 and 18 cases of primary spontaneous pneumothorax per 100,000 men in the United States each year, and 1.2 to 6 cases per 100,000 women per year. These numbers do not include collapsed lung that occurs because of injury (such as from a gunshot, stabbing, and motor vehicle accidents) or disease. Collapsed lung occurs three times more often in men than in women.

What Causes a Collapsed Lung?

In most cases, a collapsed lung is the result of injury or trauma to the chest. Injuries that cause collapsed lung include open wounds to the chest such as those from gunshot wounds, knife wounds, or shrapnel wounds from explosions. In these cases of external injury, both air from the outside and blood from injury to arteries and veins enter the chest cavity, resulting in pneumothorax and hemothorax. The lung can also collapse as a result of a closed chest wound, in which external pressure on the chest causes one or more ribs to fracture and puncture the lung. Closed chest wounds commonly result from motor vehicle accidents in which the steering wheel crushes the chest; or from other injuries in which the chest is compressed.

Pneumothorax can also occur when air blisters break open, causing air to leak into the space around the lung. This form of the disorder usually occurs when the person is exposed to changes in air pressure that can occur during scuba diving or flying at a high altitude.

There are some diseases of the lung that can increase the risk of a collapsed lung. They include asthma, chronic obstructive pulmonary disease (COPD) such as emphysema or chronic bronchitis, cystic fibrosis, tuberculosis, lung cancer, pneumonia (specifically Pneumocystis jirovecii [NU-moh-SIS-tis JEE-roh-VEK-ee-eye] pneumonia seen in people with AIDS), and whooping cough. People who have had chest or abdominal surgery, or who have been placed on a breathing machine, have an increased risk of collapsed lung.

Men are at higher risk of a collapsed lung than women. Smokers and those who abuse drugs also have an increased risk of suffering a collapsed lung. The greater the number of cigarettes smoked per day, the greater the risk of a collapsed lung. Smoking increases the risk of a collapsed lung twentyfold in men and tenfold in women compared to nonsmokers.

In some cases, the lung collapses following minimal injury or for no obvious reason. This condition is called spontaneous pneumothorax. Tall thin people seem to be at higher risk of spontaneous pneumothorax. People who have had a spontaneous pneumothorax are at greater risk of having another episode of collapsed lung.

How Do Doctors Diagnose and Treat Collapsed Lung?


When the doctor listens to the chest with a stethoscope, he or she will hear decreased or no breath sounds on the side of the chest where the lung has collapsed. If the doctor percusses (thumps) on the side of the chest where the lung has collapsed, he or she may hear a resonant sound like a booming drum. The doctor will order a chest x-ray to confirm the diagnosis of collapsed lung.


In the case of a small pneumothorax, or a small amount of air in the pleural cavity, the air is absorbed and the lung reinflates on its own when the person is given oxygen and rest. In the case of a larger collapse of the lung, the doctor will insert a needle with a tube attached between the ribs and into the space around the lungs. This tube will allow the air to leave the pleural cavity and the lung to re-expand. If the person has both blood and air in the chest cavity, two tubes will be inserted; one higher on the chest to release the air (because air rises), and one lower on the chest to drain the blood (because fluid and drainage move to a lower position). As the air and blood are released, the lung will re-expand.


Once a person has had a collapsed lung, they have an increased risk of a future collapsed lung. If the person smokes, the risk of a future collapsed lung is increased.

Can Collapsed Lung Be Prevented?

There are only a few ways to prevent a collapsed lung. As smoking can be a risk factor for collapsed lung, not smoking avoids that risk. Other preventive measures include safe driving habits, including wearing seat belts; following recommended safety procedures for the use of compressed air when scuba diving; and avoiding exposure to the disease agents that cause pneumonia and tuberculosis.

See also Chronic Obstructive Pulmonary Disease (COPD) • Lung Cancer • Pneumonia • Trauma • Tuberculosis • Wounds


Books and Articles

Daniels, Patricia, Christina Wilsdon, and Jen Agresta. Ultimate Bodypedia: An Amazing Inside-Out Tour of the Human Body. Washington, DC: National Geographic Publication, 2014.

Roberts, Martha B., editor. Pneumothorax: Classification, Treatment, and Prognostic Factors. New York: Nova Science Publishers, 2013.


MedlinePlus. “Collapsed Lung (Pneumothorax).” U.S. National Library of Medicine, National Institutes of Health. (accessed March 22, 2016).

MedlinePlus. “Pneumothorax Series.” U.S. National Library of Medicine, National Institutes of Health. (accessed March 22, 2016).


American Lung Association. 55 W. Wacker Dr., Suite 1150, Chicago, IL 60601. Toll-free: 800-LUNG-USA. Website: (accessed March 22, 2016).

National Heart, Lung, and Blood Institute. NHLBI Health Information Center, PO Box 30105, Bethesda, MD 20824-0105. Telephone: 301-592-8573. Website: (accessed March 22, 2016).

Disclaimer:   This information is not a tool for self-diagnosis or a substitute for professional care.

(MLA 8th Edition)