Pneumothorax (collapsed lung): causes, types, diagnosis and treatment

Anatomy and mechanism

The pleural space lies between two layers: the visceral pleura covering the lung and the parietal pleura lining the chest wall. A breach in the lung surface or chest wall allows atmospheric air to enter the pleural space. This can be caused by rupture of a small blister (bleb) on the lung surface, penetrating injury to the chest, or iatrogenic causes related to medical procedures. As air accumulates the lung loses its negative intrathoracic pressure and recoils inward, reducing effective lung volume and gas exchange.

Types and common causes

• Primary spontaneous pneumothorax: occurs without preceding lung disease, often in otherwise healthy people, sometimes associated with ruptured subpleural blebs.
• Secondary spontaneous pneumothorax: develops in people with known lung disease such as chronic obstructive pulmonary disease (COPD), cystic fibrosis, or certain infections and lung disorders.
• Traumatic pneumothorax: follows blunt or penetrating chest trauma, rib fracture, or injury from medical procedures.
• Iatrogenic pneumothorax: results from diagnostic or therapeutic interventions (for example central line insertion, lung biopsy, or mechanical ventilation).
• Tension pneumothorax: a severe variant in which air enters the pleural space but cannot escape, causing progressive intrathoracic pressure rise, mediastinal shift and potential cardiovascular collapse. This is life‑threatening and demands immediate intervention.

Symptoms and clinical signs

Symptoms range from mild chest discomfort and shortness of breath to severe respiratory distress. Typical findings on examination include unilateral chest pain, rapid breathing, reduced breath sounds on the affected side, hyperresonant percussion, and sometimes low oxygen saturation. In tension pneumothorax there may be distended neck veins, low blood pressure and tracheal deviation away from the affected side.

Investigation and diagnosis

Diagnosis is usually confirmed by chest radiography, which shows air in the pleural space and collapse of lung tissue. Computed tomography (CT) offers greater sensitivity and can detect small pneumothoraces or underlying lung disease. Point‑of‑care ultrasound is increasingly used at the bedside to detect absence of lung sliding or the presence of a lung point sign, providing rapid assessment in unstable patients. Physical examination and clinical context guide urgency and the need for immediate decompression versus further imaging.

Treatment and outcomes

Management depends on size, symptoms, cause and patient stability. Options include:

1. Observation and supplemental oxygen for small, stable pneumothoraces that are likely to reabsorb.
2. Needle aspiration or simple chest tube (thoracostomy) to evacuate pleural air for larger or symptomatic cases.
3. Emergency needle decompression followed by chest tube for suspected tension pneumothorax to rapidly relieve pressure and restore circulation.
4. Surgical approaches (video‑assisted thoracoscopic surgery, VATS) to repair persistent air leaks, remove blebs, or perform pleurodesis to reduce recurrence risk.

Most patients recover with appropriate treatment, though those with underlying lung disease or recurrent events face higher risk of complications and future episodes. Long‑term management may address smoking cessation, treatment of lung disease, and preventive surgical options in recurrent cases.

Important distinctions and practical notes

• Not all pneumothoraces require invasive treatment; clinical assessment guides whether observation is sufficient.
• Rapid recognition of tension pneumothorax and immediate decompression are critical to prevent cardiovascular collapse — if suspected, do not delay for imaging.
• Patients with chest trauma should be assessed for concurrent injuries to structures such as the heart or large vessels, and those with suspected primary lung disease may benefit from specialist respiratory follow‑up involving imaging and smoking cessation counseling.
• For general information about lung structure and function see resources on the lung.

Pneumothorax management is directed by severity, the underlying cause, and patient factors. Early recognition and appropriate intervention usually lead to favorable outcomes, while delays in treating tension pneumothorax can be fatal.