Tension Pneumothorax

How tension pneumothorax develops

The lungs are surrounded by a thin pleural space. In a simple pneumothorax, air enters this space and part of the lung collapses. In a tension pneumothorax, the tear acts like a one-way valve: air gets in with each breath but cannot get out. Pressure rises until it:

• fully collapses the lung on that side
• pushes the heart and central structures (mediastinum) toward the other side
• kinks and compresses the large veins, so blood cannot return to the heart
• causes a sudden fall in cardiac output, shock and cardiac arrest

It can progress within minutes, especially in people on positive-pressure ventilation.

Causes

• chest trauma: stab and gunshot wounds, rib fractures, car crashes and falls
• mechanical ventilation: high pressures can force air through a lung tear
• medical procedures: central line insertion, lung biopsy, thoracentesis, CPR
• spontaneous pneumothorax progressing to tension (uncommon)
• lung disease: COPD, cystic fibrosis and infections that weaken lung tissue

Signs and symptoms

• severe, worsening shortness of breath
• sharp chest pain on one side
• rapid breathing and racing heart
• low oxygen levels and blue or gray lips
• low blood pressure and signs of shock: pale, sweaty skin, confusion
• reduced or absent breath sounds on the affected side
• swollen neck veins (may be absent if there is blood loss)
• tracheal shift away from the affected side (a late sign)
• in ventilated patients: sudden rising airway pressures, falling oxygen and blood pressure

Diagnosis

Tension pneumothorax is a clinical diagnosis. When it is suspected in an unstable patient, treatment comes before imaging. In more stable situations, or if immediately available:

• bedside ultrasound shows the absence of lung sliding
• chest X-ray or CT shows the collapsed lung and shift of the heart

Doctors also consider other causes of sudden collapse after chest injury, such as cardiac tamponade and major bleeding.

Emergency treatment

1. Decompression: releasing the trapped air immediately, either by: - needle decompression: a large needle inserted between the ribs, usually in the side of the chest (4th or 5th space) or the upper front chest, or - finger thoracostomy: a small surgical opening, often used in trauma care and ventilated patients
2. Chest tube (tube thoracostomy): inserted promptly to keep air draining and allow the lung to re-expand.
3. Oxygen and supportive care, treating any bleeding or other injuries.

Recovery and outlook

With rapid decompression, most people recover well. The chest tube stays until the air leak stops and the lung re-expands, usually days. Delayed treatment can be fatal. After any pneumothorax, people are usually advised to avoid flying until the lung has fully healed and to avoid scuba diving unless treated surgically.

Frequently asked questions

What is a tension pneumothorax?

A tension pneumothorax is a collapsed lung in which air keeps entering the chest cavity but cannot escape, building pressure that compresses the heart and the other lung. It is a life-threatening emergency requiring immediate decompression.

What are the signs of tension pneumothorax?

Signs include severe breathlessness, one-sided chest pain, fast breathing and heart rate, low oxygen, falling blood pressure, absent breath sounds on one side, and sometimes swollen neck veins and a shifted windpipe.

What causes tension pneumothorax?

The most common causes are chest injuries such as stab wounds, gunshots and rib fractures, mechanical ventilation, and medical procedures like central line insertion. Occasionally a spontaneous pneumothorax develops tension.

How is tension pneumothorax treated?

It is treated immediately by releasing the trapped air with a needle or a small surgical opening in the chest wall, followed by placement of a chest tube to allow the lung to re-expand.