A collapsed lung, medically known as a pneumothorax, occurs when air leaks into the space between the lung and the chest wall. This air accumulation creates external pressure, preventing the lung from expanding fully when a person inhales. The buildup of this pressure causes the lung to shrink, or collapse, sometimes partially or completely. Because a pneumothorax can rapidly impair breathing and circulation, it requires immediate medical evaluation and treatment.
The Physics of a Collapsed Lung
Normal breathing relies on a finely balanced pressure system within the chest cavity. Each lung is surrounded by the pleura, a double-layered membrane creating the pleural space. This space maintains a slightly negative pressure, acting like a vacuum that keeps the lung tissue pulled outward against the chest wall, allowing inflation with each breath. Lung tissue naturally possesses an elastic recoil, constantly trying to shrink inward.
When a hole or tear occurs in the lung or chest wall, air rushes into the pleural space, instantly neutralizing the negative pressure. The loss of the vacuum effect allows the lung’s elastic recoil to take over, causing the tissue to pull away from the chest wall and collapse. The amount of air determines the degree of collapse and the severity of breathing difficulty, reducing the lung’s ability to exchange oxygen and carbon dioxide.
Common Triggers and Types
Pneumothorax is categorized based on the origin of the air leak: spontaneous or traumatic.
Spontaneous Pneumothorax
A spontaneous pneumothorax occurs without external injury and is subdivided into two types. Primary spontaneous pneumothorax happens in individuals without underlying lung disease, often due to the rupture of small, air-filled sacs called blebs on the lung surface. This type is common in tall, thin young men and smokers. Secondary spontaneous pneumothorax develops in people with pre-existing lung conditions that weaken lung tissue, such as chronic obstructive pulmonary disease (COPD), cystic fibrosis, or severe asthma. The compromised tissue is more susceptible to tearing, allowing air to escape. Both types occur without warning, even while the person is at rest.
Traumatic Pneumothorax
A traumatic pneumothorax results from a direct injury to the chest wall, allowing outside air to enter the pleural space or air to leak from a damaged lung. Causes include blunt trauma (car accidents or falls) or penetrating injuries (stab or gunshot wounds). A fractured rib can also puncture the lung, causing the air leak.
Tension Pneumothorax
A particularly dangerous presentation is a tension pneumothorax, which operates under a one-way valve effect. Air enters the pleural space during inhalation but becomes trapped, unable to escape during exhalation. This rapidly escalating pressure pushes the affected lung, heart, and major blood vessels toward the opposite side of the chest (mediastinal shift). This severe pressure buildup compromises the function of the heart and the unaffected lung, representing a life-threatening medical emergency.
Recognizing the Signs
Symptoms of a collapsed lung appear suddenly and intensify rapidly. The most characteristic sign is a sharp, stabbing pain on one side of the chest that worsens with deep breathing or coughing. This pain results from the air separating the pleural layers and irritating nerve endings. Shortness of breath (dyspnea) is also prominent, ranging from mild discomfort to severe difficulty breathing, depending on the size of the collapse.
As lung function decreases, the person may develop a rapid heart rate as the body compensates for reduced oxygen supply. In extensive cases, a lack of oxygen may cause the skin, lips, or fingernails to take on a bluish tint, known as cyanosis. Medical professionals confirm the condition using imaging tests, as symptoms alone are not definitive. A chest X-ray is the standard initial diagnostic tool, clearly showing the air pocket and the shrunken lung tissue. A computed tomography (CT) scan may be used to provide a more detailed view of the lung and chest structures, especially when the diagnosis is unclear or to assess the underlying cause.
Treatment and Resolution
Treatment for a collapsed lung is determined by the size of the air pocket and the severity of the symptoms.
Observation and Oxygen
If the pneumothorax is small and the patient is stable with minimal symptoms, the medical team may choose observation. This allows the body to naturally reabsorb the excess air over several days. Supplemental oxygen therapy can be given to speed up this reabsorption process.
Active Air Removal
For a larger collapse or significant symptoms, the air must be actively removed to allow the lung to re-expand.
- Needle Aspiration: A thin, hollow needle is inserted into the chest cavity to withdraw the trapped air. This method is often sufficient for initial, uncomplicated cases.
- Chest Tube Insertion (Thoracostomy): This is the most common treatment for extensive pneumothorax. A flexible plastic tube is inserted into the pleural space and connected to a drainage system. This continuously removes air, re-establishing the negative pressure needed for the lung to fully inflate. The tube remains in place until the air leak has sealed and the lung has remained expanded.
Surgical Intervention
If the air leak persists despite tube drainage, or if the person experiences recurrent pneumothoraces, surgery may be necessary. Procedures like pleurodesis involve making the lung surface stick to the chest wall, preventing future air accumulation. Following resolution, people are advised to avoid activities involving significant pressure changes, such as scuba diving or flying in unpressurized aircraft, until cleared by a physician.