A pneumothorax is a collapsed lung caused by air leaking into the space between your lung and your chest wall. Normally, this space (called the pleural space) has negative pressure that keeps your lung inflated. When air gets in, that pressure balance is disrupted, and the lung partially or fully collapses, reducing your ability to breathe.
How a Lung Collapses
Your lungs don’t inflate on their own. They expand because the pleural space surrounding them maintains lower pressure than the atmosphere, essentially pulling the lung tissue outward as your chest wall moves. Think of it like a vacuum seal. When air enters that sealed space, the vacuum breaks. The lung’s natural elastic recoil takes over, and it starts to shrink inward. The more air that accumulates, the more the lung collapses, and the less oxygen your body can take in.
Air gets into the pleural space through one of two routes: a puncture through the chest wall (from injury or a medical procedure) or a rupture of the lung’s own surface from the inside. In spontaneous cases, the rupture usually happens at small, weak spots on the lung surface called blebs or bullae, which are essentially tiny air-filled blisters.
Types of Pneumothorax
Primary Spontaneous Pneumothorax
This type strikes people with no known lung disease. It often affects young, tall, thin males, seemingly out of nowhere. A small bleb on the lung surface ruptures, air leaks out, and the lung partially deflates. It can happen at rest or during normal activity. Despite the absence of underlying disease, recurrence rates are high: studies report that 20 to 60% of people who have one episode will have another.
Secondary Spontaneous Pneumothorax
This occurs in people who already have a lung condition, most commonly COPD. The diseased lung tissue is more fragile and prone to rupture. Secondary cases tend to be more dangerous because the person’s lung function is already compromised, so even a small collapse can cause serious breathing difficulty.
Traumatic Pneumothorax
A blow to the chest, a rib fracture, a stabbing, or a gunshot wound can puncture the chest wall or the lung itself, allowing air into the pleural space. Car accidents and falls are common causes.
Iatrogenic Pneumothorax
Some medical procedures carry a risk of accidentally introducing air into the pleural space. The most common culprit is placement of a central venous line into the subclavian vein (a large vein near the collarbone). Lung needle biopsies and mechanical ventilation are also well-known causes.
Tension Pneumothorax
This is the most dangerous form. Air enters the pleural space but can’t escape, creating a one-way valve effect. Pressure builds continuously, pushing the heart and major blood vessels to the opposite side of the chest. This shift compresses the large veins that return blood to the heart, causing blood pressure to plummet and potentially triggering cardiac arrest within minutes. Tension pneumothorax is a life-threatening emergency that requires immediate intervention.
What It Feels Like
The most common symptom is sudden, sharp chest pain on the affected side, often accompanied by shortness of breath. The pain may feel worse when you breathe in deeply. In a small pneumothorax, symptoms can be mild enough that some people wait hours or even days before seeking care. In larger collapses, breathing becomes noticeably labored, and you may feel your heart racing as your body tries to compensate for reduced oxygen.
Tension pneumothorax has more dramatic signs: severe difficulty breathing, a rapid pulse, pale or bluish skin, and a sense that something is seriously wrong. The neck veins may appear swollen and distended because blood is backing up as it struggles to return to the compressed heart.
Risk Factors
Smoking is the strongest modifiable risk factor. In people with otherwise normal lungs, every 10 additional pack-years of smoking history increases the odds of pneumothorax by about 20%. Smoking damages small airways and promotes the formation of blebs, even before any diagnosable lung disease develops.
Men are roughly 1.5 times more likely to experience a pneumothorax than women. Tall, thin body types have long been considered a classic risk profile, though at least one large study found that height was not independently associated with risk once other factors like smoking were accounted for. Having a previous pneumothorax is itself a major risk factor, given the high recurrence rates.
How It’s Diagnosed
A chest X-ray is the standard first step. It can reveal the air pocket in the pleural space and show how much the lung has collapsed. In less obvious cases, or when more detail is needed, a CT scan provides a clearer picture and can identify blebs or underlying lung disease that might have caused the collapse. During a physical exam, a doctor listening to your chest will notice reduced or absent breath sounds on the affected side, and tapping on the chest may produce a hollow, drum-like sound instead of the normal dull tone.
Treatment Options
Treatment depends on the size of the pneumothorax and how much it’s affecting your breathing.
For small, minimally symptomatic cases, observation alone may be enough. The 2023 British Thoracic Society guidelines recommend that conservative management (essentially watching and waiting) can be considered for primary spontaneous pneumothorax regardless of size, as long as there is no significant pain, breathlessness, or physiological compromise. The body gradually reabsorbs the trapped air over days to weeks.
When intervention is needed, two main options exist: needle aspiration and chest tube drainage. Needle aspiration involves inserting a needle into the pleural space and drawing out the trapped air with a syringe. Chest tube drainage involves placing a small tube between the ribs that continuously drains air, sometimes connected to a one-way valve or suction device. Research comparing the two approaches has found no significant difference in immediate success rates, complication rates, one-week success rates, or recurrence rates at three months. Smaller chest tubes appear to work as well as larger ones while causing less pain.
For tension pneumothorax, emergency needle decompression is performed immediately, inserting a large needle into the chest to release the trapped, pressurized air. This is a stabilizing measure, typically followed by chest tube placement.
Surgery to Prevent Recurrence
Because recurrence is so common, surgery becomes a consideration after a second pneumothorax, or sometimes after a first episode in certain circumstances (such as a persistent air leak that won’t seal on its own, or if the person has a high-risk occupation like piloting or diving).
The most common surgical approach is video-assisted thoracoscopic surgery (VATS), a minimally invasive procedure performed through small incisions. The surgeon can remove blebs and perform pleurodesis, a technique that intentionally irritates the pleural surfaces so they scar together, eliminating the space where air could accumulate. This dramatically reduces the chance of another collapse. VATS is generally well tolerated, with a shorter recovery time and less pain than traditional open chest surgery.
Recovery and What to Expect
A small pneumothorax treated conservatively may resolve within one to two weeks, with follow-up X-rays to confirm the lung has re-expanded. If a chest tube is placed, hospital stays typically range from a few days to a week, depending on how quickly the air leak seals. After surgery, most people return to normal activity within two to four weeks.
During recovery, you’ll likely be advised to avoid air travel and scuba diving until imaging confirms full re-expansion, since pressure changes at altitude or depth could worsen a healing pneumothorax. Smoking cessation is strongly recommended, both to aid healing and to lower the already significant risk of recurrence.