What Causes Collapsed Lung?

A collapsed lung happens when air escapes into the space between the lung and the chest wall, or when something blocks an airway so that a section of lung deflates. The medical name is pneumothorax. It can strike a tall, thin young man for no clear reason, follow a rib fracture, or develop as a complication of lung disease like COPD. Each cause leads to the same result: air in the wrong place, and a lung that cannot fully expand.

What Causes Collapsed Lung?

The most common causes fall into two groups. In one, air leaks from inside the lung into the pleural space — the thin gap between the lung and the chest wall. In the other, the lung tissue itself fails to inflate because an airway is blocked or the lung is compressed by something else.

Pneumothorax is the type most people mean when they say “collapsed lung.” It has several distinct causes:

• Spontaneous pneumothorax. A small bleb or blister on the lung surface ruptures without any injury. This is most common in tall, thin young men, though it can happen to anyone. It is also more frequent in smokers.
• Underlying lung disease. COPD, cystic fibrosis, and prior lung infections damage lung tissue and raise the risk of a rupture. This is called secondary spontaneous pneumothorax.
• Chest injury. A broken rib, a stab wound, or a blunt blow to the chest can tear the lung and let air escape.
• Medical procedures. Needle biopsies, central line placement, and chest surgery can puncture the lung. This is a known risk of certain procedures.

There is a second, separate meaning of “collapsed lung” that gets less attention. In atelectasis, the lung tissue itself deflates because an airway is plugged with mucus, a tumor, or a foreign object, or because pressure from outside squeezes it shut. The lung does not leak air — it simply cannot fill. Both conditions cause shortness of breath, but they are different problems with different treatments.

What Is a Spontaneous Pneumothorax?

A spontaneous pneumothorax is a collapsed lung that happens without any injury or obvious trigger. The word “spontaneous” means it came on its own.

In a primary spontaneous pneumothorax, the person has no known lung disease. Small air-filled sacs called blebs form near the surface of the lung, often at the top. When one ruptures, air leaks into the pleural space. The chest wall and lung are separated by that trapped air, and the lung deflates like a balloon losing its seal.

Who tends to get this? Tall, thin people between their teens and their 30s are the classic group, and men are affected more often than women. Smoking is a well-established risk factor — even light smoking raises the risk. Some research suggests that the shape of the chest in tall people may play a role, though the exact reason some people develop blebs and others do not is not fully understood.

In a secondary spontaneous pneumothorax, the person already has damaged lungs. COPD is one of the most common underlying conditions. Cystic fibrosis, tuberculosis, and certain inherited connective tissue disorders also raise risk. These cases tend to be more serious because the lungs have less reserve to begin with.

What Does a Collapsed Lung Feel Like?

Sudden, sharp chest pain on one side is the most common first symptom. It often comes on at rest, or with no warning at all, and may be worse when you breathe in. Shortness of breath usually follows.

Other signs can include:

• Pain that may travel to the shoulder or back on the same side
• A rapid heart rate
• Feeling that you cannot take a full breath
• In severe cases, bluish lips or fingertips, which signal low oxygen

The size of the collapse matters. A small pneumothorax may cause only mild discomfort and can sometimes be managed with observation. A large one, or one in a person with underlying lung disease, can cause significant breathing difficulty. A rare but life-threatening form called tension pneumothorax builds pressure in the chest that pushes on the heart and the other lung. It is a medical emergency. Signs include severe breathlessness, low blood pressure, and one side of the chest that does not move normally with breathing.

One point worth knowing: the amount of pain does not reliably tell you how large the collapse is. A small leak can hurt sharply, and a larger one can sometimes feel milder. Only imaging can show the size.

How Is a Collapsed Lung Diagnosed?

A chest X-ray is usually the first test. It shows air in the pleural space and how far the lung has pulled away from the chest wall. In an emergency, clinicians may rely on physical exam findings and act quickly.

A CT scan gives more detail and can find small blebs or underlying lung disease. Ultrasound is increasingly used in emergency settings and can detect a pneumothorax at the bedside. Blood oxygen measurement helps show how well the lungs are working.

For atelectasis, the picture is different. Imaging shows a section of lung that has shrunk or become dense, often with a visible blockage in the airway. The treatment then focuses on clearing the airway or relieving whatever is pressing on the lung.

How Is a Collapsed Lung Treated?

Treatment depends on the size, the cause, and the person’s overall health. There is no single approach, and what is right for one person may not be right for another.

A small primary spontaneous pneumothorax in a stable person may be watched with repeat X-rays while the air reabsorbs on its own. This can take days to weeks, and clinicians weigh this against the risk of a slow recovery.

When treatment is needed, common options include:

• Oxygen therapy. Supplemental oxygen speeds up the reabsorption of trapped air.
• Needle or catheter aspiration. A needle or small tube removes air from the pleural space.
• Chest tube placement. A tube inserted between the ribs drains air and lets the lung re-expand. This is common for larger or recurrent collapses.
• Surgery. For repeated collapses, surgery can remove blebs and seal the lung surface to lower the chance of another episode.

Tension pneumothorax is treated immediately with needle decompression, followed by a chest tube. Delaying treatment in that situation is dangerous.

For atelectasis, treatment targets the cause. That may mean clearing mucus with breathing exercises or devices, treating an infection, removing a blockage, or repositioning the body to help the lung open.

Can a Collapsed Lung Come Back?

Yes. Recurrence is common, especially after a primary spontaneous pneumothorax. Many repeat episodes happen within the first year or two, though they can occur later.

Several things raise the chance of a repeat:

• Smoking, which is the most modifiable risk factor
• Underlying lung disease such as COPD
• Prior episodes
• Certain inherited connective tissue conditions

Stopping smoking is the single most useful step a person can take to lower recurrence risk. Some people with repeated collapses are referred for surgery to reduce the chance of another episode. The decision depends on individual circumstances and should be made with a clinician.

When Should You Get Medical Help?

Sudden chest pain with shortness of breath needs urgent medical attention. Call emergency services if breathing becomes severe, if there is bluish color to the lips, or if the person feels faint or is losing consciousness.

Do not wait to see if it passes. A collapsed lung can worsen quickly, and the serious forms need treatment without delay. If you have had a collapsed lung before and feel the same pain again, seek care promptly — recurrence is common, and early treatment is safer.