Pneumothorax

A pneumothorax is air within the pleural space. It may be spontaneous (primary, with no known lung disease, or secondary to conditions such as COPD), traumatic or iatrogenic. A tension pneumothorax is a clinical emergency in which air accumulates under pressure and impairs venous return.

Epidemiology

Primary spontaneous pneumothorax classically affects tall, thin young men, and smoking strongly increases the risk. Secondary pneumothorax peaks in older patients with established lung disease, in whom even a small air leak is poorly tolerated.

Clinical presentation

Sudden pleuritic chest pain and breathlessness are typical. Examination may show reduced breath sounds and hyper-resonance on the affected side. Hypotension, tachycardia, distended neck veins and tracheal deviation suggest tension physiology.

Radiographic features

Plain radiograph

• A thin, white visceral pleural line with no lung markings beyond it
• Increased lucency of the affected hemithorax
• On supine films, the deep sulcus sign: a deep, lucent costophrenic angle
• Tension: mediastinal shift away from the affected side, flattening or inversion of the hemidiaphragm, widened intercostal spaces

CT

CT is the most sensitive test and shows even small anterior collections in supine trauma patients. It also shows underlying bullae or lung disease.

Ultrasound

Absent lung sliding, absent B-lines and the presence of a lung point support the diagnosis at the bedside.

Treatment and prognosis

Small, stable primary pneumothoraces may be observed. Larger or symptomatic collections are aspirated or drained. Tension pneumothorax is treated with immediate decompression and should be a clinical diagnosis — treatment should not wait for imaging.

Differential diagnosis

• Skin folds (lines that extend beyond the chest wall, with lung markings visible beyond them)
• Large bullae
• Medial border of the scapula

Practical points

Always look at the apices and, on supine films, at the costophrenic angles. A pneumothorax on an expiratory film looks relatively larger, but expiratory films are not routinely needed.