A collapsed lung, medically termed a pneumothorax, occurs when air collects in the chest cavity outside the lung, causing the organ to deflate partially or fully. This condition happens when a puncture or tear allows air to escape the lung’s airways or enter from outside the chest wall, disrupting the pressure balance that keeps the lung inflated. A pneumothorax can range in severity from a small, self-resolving air leak to a life-threatening emergency that requires immediate medical intervention.
Understanding the Physics of a Collapsed Lung
The mechanism behind a pneumothorax is rooted in the physics of the chest cavity. The lungs are contained within the pleural cavity, which is lined by two thin membranes: the visceral pleura covering the lung and the parietal pleura lining the chest wall. In a healthy state, this cavity maintains a negative pressure, meaning the pressure inside is lower than the atmospheric pressure. This pressure differential acts like a suction cup, pulling the lung tissue outward and keeping it fully expanded against its natural elastic recoil.
When a lung is punctured, either from an external injury or an internal air-filled blister (bleb) rupturing, air rushes into the pleural space. This influx immediately equalizes the negative pressure within the pleural cavity with the atmospheric pressure. The loss of the pressure gradient causes the lung’s inherent elasticity to take over, forcing the tissue to recoil inward and collapse.
The amount of collapse depends on how much air leaks into the space. A continuous leak can lead to a tension pneumothorax, where the damaged tissue acts as a one-way valve. This valve allows air to enter the pleural space during inhalation but prevents it from escaping during exhalation. The rapid buildup of positive pressure collapses the affected lung completely and shifts the mediastinum—the area containing the heart and major blood vessels—to the opposite side of the chest. This extreme pressure compromises the function of the other lung and reduces blood return to the heart, leading to circulatory failure.
Recognizing the Signs and Symptoms
The most common sign of a pneumothorax is the sudden onset of sharp, stabbing chest pain. This pain is often localized to one side of the chest and feels worse when the person takes a deep breath or coughs. The sensation arises from the irritation of the parietal pleura as the lung separates from the chest wall.
Individuals experience shortness of breath (dyspnea) because the collapsed lung cannot participate fully in gas exchange. The severity correlates directly with the size of the pneumothorax; a small air leak may cause mild breathlessness, while a large leak results in rapid, shallow breathing and distress. In severe cases, particularly with a tension pneumothorax, the lack of oxygenation can manifest as a rapid heart rate, low blood pressure, and cyanosis (a bluish tint to the skin, lips, or nails). The presence of these symptoms requires immediate emergency medical attention, as they indicate a compromise of respiratory and cardiovascular function.
Standard Emergency Treatments
Treatment for a pneumothorax is determined by the size of the air collection and the patient’s stability. For a very small pneumothorax where the patient is stable and experiencing minimal symptoms, the approach is simple observation. The medical team monitors the patient with serial chest X-rays to ensure the air leak has stopped and the trapped air is being naturally reabsorbed by the body, a process that can take several weeks.
If the pneumothorax is larger or the patient is symptomatic, active intervention is necessary to remove the air and allow the lung to re-expand. One procedure is needle aspiration, where a thin needle and catheter are inserted between the ribs to withdraw the accumulated air from the pleural space. This technique is often used for a first-time spontaneous pneumothorax and is a minimally invasive way to achieve immediate re-expansion.
For larger air leaks, recurrent episodes, or cases resulting from trauma, chest tube insertion is the standard treatment. A flexible tube is placed into the chest cavity and connected to a one-way valve system that continuously drains air, preventing re-entry into the pleural space. This system re-establishes negative pressure, allowing the lung to fully reinflate and heal while the air leak seals.
If the air leak persists despite chest tube drainage, or if the patient experiences a second pneumothorax, surgical intervention may be required. The most common approach is Video-Assisted Thoracoscopic Surgery (VATS), a minimally invasive procedure used to repair the leaking area and often perform a pleurodesis. Pleurodesis involves mechanically or chemically irritating the pleural membranes so they scar and permanently adhere to one another. This process eliminates the pleural space and reduces the risk of future collapse.
Recovery and Long-Term Outlook
Once the immediate emergency has passed and the lung has re-expanded, the recovery phase begins, typically lasting a few weeks to a couple of months. Patients are encouraged to perform deep breathing exercises, which help promote the restoration of lung function and prevent complications like pneumonia.
Restrictions on certain activities are a major part of post-pneumothorax recovery due to the risk of air pressure changes. Patients are advised to wait at least one to three weeks after the air leak has fully resolved before flying on a commercial airplane. This precaution is based on Boyle’s Law: residual trapped air in the chest would expand at the lower cabin pressure, potentially causing the pneumothorax to recur or worsen.
Scuba diving is a significantly greater risk and is generally contraindicated permanently unless the patient has undergone a definitive procedure like a surgical pleurectomy. The high pressures encountered at depth, and the rapid expansion of trapped gas on ascent, can cause a tension pneumothorax. The risk of recurrence for a spontaneous pneumothorax ranges widely, with many individuals experiencing a second episode, especially if they are smokers. Regular follow-up with imaging, such as chest X-rays, is necessary to confirm complete healing and lung expansion.