Introduction
Tension pneumothorax is a life-threatening condition characterized by the progressive accumulation of air in the pleural space under pressure, leading to collapse of the affected lung and compression of intrathoracic structures. It is a form of pneumothorax that results in significant hemodynamic instability and requires immediate recognition and intervention to prevent death.
Definition
Tension pneumothorax occurs when air enters the pleural space and cannot escape, creating a one-way valve effect. This leads to increasing intrapleural pressure, lung collapse, and mediastinal shift that compromises cardiopulmonary function.
Pathophysiology
The key mechanism in tension pneumothorax is the creation of a “ball-valve” effect at the site of injury in the lung or chest wall. With each inspiration, air enters the pleural space but cannot exit during expiration. This results in:
- Progressive rise in intrathoracic pressure.
- Compression of the ipsilateral and eventually contralateral lung.
- Mediastinal shift toward the contralateral side.
- Compression of the superior and inferior vena cava, reducing venous return to the heart.
- Decreased cardiac output and shock.
Etiology
Tension pneumothorax can occur due to several causes:
1. Trauma
- Penetrating chest injury
- Blunt trauma with rib fracture
- Barotrauma (e.g., from mechanical ventilation)
2. Iatrogenic
- Central line insertion
- Positive pressure ventilation
- Thoracentesis
- Chest tube malfunction
3. Spontaneous
- Primary spontaneous (usually in tall, thin young males)
- Secondary spontaneous (e.g., in COPD, cystic fibrosis, tuberculosis)
Clinical Features
The hallmark of tension pneumothorax is acute respiratory and hemodynamic compromise. Signs and symptoms include:
- Sudden-onset dyspnea
- Pleuritic chest pain
- Hypotension and tachycardia
- Distended neck veins (due to impaired venous return)
- Tracheal deviation away from the affected side (late sign)
- Absent breath sounds on the affected side
- Hyperresonance on percussion
- Cyanosis and signs of shock
Diagnosis
Tension pneumothorax is primarily a clinical diagnosis. Delaying treatment for imaging can be fatal.
Imaging (if patient stable):
- Chest X-ray: Collapsed lung, mediastinal shift, depressed diaphragm on affected side.
- Ultrasound (eFAST): Absence of lung sliding (barcode sign).
Emergency Management
Tension pneumothorax is a medical emergency and should be treated immediately:
1. Immediate Needle Decompression
- Site: 2nd intercostal space in the midclavicular line, or 5th intercostal space at the anterior axillary line.
- Technique: Large-bore (14–16G) needle inserted into the pleural space to relieve pressure.
2. Chest Tube Insertion (Tube Thoracostomy)
- After needle decompression, a chest tube is placed in the 4th or 5th intercostal space in the mid- to anterior axillary line.
- Connected to an underwater seal drainage system.
3. Oxygen and Supportive Care
- High-flow oxygen
- Intravenous fluids for hypotension
- Monitoring and ICU care as needed
Prognosis
If recognized and treated promptly, patients can recover fully. Delayed diagnosis or treatment can lead to:
- Cardiac arrest
- Hypoxic brain injury
- Death
Prevention
In high-risk situations such as mechanical ventilation or trauma, careful monitoring and early intervention are critical to preventing progression to tension pneumothorax.
Conclusion
Tension pneumothorax is a rapidly fatal condition if left untreated. It should be high on the differential diagnosis list in any patient with sudden respiratory distress, especially in trauma or ventilated patients. Immediate decompression, followed by chest tube placement, is life-saving and should not be delayed for diagnostic confirmation.