Tension pneumothorax

Background

• Progressive accumulation of air in the pleural space with a one-way valve mechanism
• Air enters on inspiration but cannot escape on expiration
• Causes mediastinal shift, decreased venous return, and cardiovascular collapse
• A clinical diagnosis — treatment should NOT be delayed for imaging
• Most common in trauma, positive pressure ventilation, and after procedures (central line, thoracentesis)

Etiology

• Traumatic pneumothorax (penetrating or blunt)
• Positive pressure ventilation (mechanical ventilation, NIPPV, BVM)
• Iatrogenic (central venous catheterization, thoracentesis, nerve blocks)
• Spontaneous (especially in tall, thin males; underlying COPD, asthma)

Clinical Features

• Hypotension and tachycardia (most sensitive findings)
• Respiratory distress, tachypnea, hypoxia
• Decreased or absent breath sounds on affected side
• Tracheal deviation away from affected side (late finding, unreliable in acute setting)
• Jugular venous distension (may be absent with concurrent hypovolemia)
• Hyperresonance to percussion on affected side
• Subcutaneous emphysema
• PEA arrest or sudden cardiovascular collapse
• Consider in intubated patients with acute deterioration (DOPE mnemonic)

Differential Diagnosis

• Simple pneumothorax
• Hemothorax
• Cardiac tamponade
• Massive pulmonary embolism
• Right mainstem intubation
• Auto-PEEP / air trapping
• Myocardial infarction

Evaluation

• Clinical diagnosis — do NOT delay treatment for CXR or CT
• Point-of-care ultrasound (POCUS): absent lung sliding on affected side (high sensitivity)
• CXR (if time permits): hyperlucency, absent lung markings, mediastinal shift, deep sulcus sign (supine)
• CT chest: definitive but rarely indicated acutely

Management

Immediate Decompression

• Needle decompression (temporizing measure):
  • 14-16 gauge angiocatheter
  • Site: 5th intercostal space, anterior axillary line (preferred) or 2nd ICS midclavicular line
  • Insert over the top of the rib (avoid neurovascular bundle on inferior rib margin)
  • Rush of air confirms diagnosis
  • May fail due to chest wall thickness — consider longer catheter (8 cm) or finger thoracostomy

Definitive Treatment

• Tube thoracostomy (28-36 Fr)
  • Required after needle decompression
  • 5th ICS, anterior to mid-axillary line
  • Connect to underwater seal / Pleurovac
• In cardiac arrest: bilateral finger thoracostomies

Cardiac Arrest

• Tension pneumothorax is a reversible cause of PEA arrest (the T in H's and T's)
• Bilateral needle or finger thoracostomy during CPR
• If ROSC not achieved after decompression, consider other causes

Disposition

• Admit all patients with tension pneumothorax
• ICU admission if hemodynamic instability, mechanical ventilation, or ongoing air leak
• Trauma surgery or thoracic surgery consultation

See Also

• Spontaneous pneumothorax
• Chest tube
• Hemothorax
• Thoracic trauma
• Deterioration After Intubation (DOPE)