Tension Pneumothorax

Life-threatening accumulation of air within the pleural space under progressively increasing pressure via a one-way valve mechanism (air enters on inspiration but cannot escape on expiration), causing complete lung collapse and progressive mediastinal shift, compressing the contralateral lung and great vessels, resulting in obstructive shock and cardiac arrest if untreated.

This is a clinical diagnosis requiring IMMEDIATE treatment ; imaging should never delay decompression.

Causes: trauma (penetrating or blunt chest injury, most common), iatrogenic (central line insertion, mechanical ventilation with barotrauma, thoracocentesis), spontaneous pneumothorax progressing to tension physiology.

• Severe respiratory distress, tachypnea, tachycardia progressing rapidly to hypotension and cardiovascular collapse

• Unilateral absent/reduced breath sounds on affected side

• Hyperresonance to percussion on affected side

• Reduced chest wall movement on affected side

• Tracheal deviation AWAY from affected side ; classic but often a late/unreliable sign, do not wait for this to act

• Raised JVP (impaired venous return from mediastinal shift)

• Hypotension, cyanosis, reduced consciousness ; obstructive shock

• In a ventilated patient: sudden increase in ventilator pressures, desaturation, hemodynamic collapse ; high suspicion in any deteriorating ventilated patient, especially post-procedure or with chest trauma

• Subcutaneous emphysema may be palpable

THIS IS A CLINICAL DIAGNOSIS ; treat immediately based on clinical findings in a hemodynamically unstable patient. Do NOT wait for chest X-ray or CT before decompressing ; imaging delay can be fatal.

• If the patient is stable enough that diagnosis is uncertain: CXR may show pneumothorax with mediastinal shift, flattened/inverted diaphragm ; but true tension physiology with hemodynamic compromise should not wait for this

• eFAST ; pleural views can rapidly identify pneumothorax at bedside (absent lung sliding, "barcode sign" on M-mode) if immediately available without delaying treatment

• Once decompressed, CXR confirms resolution and chest drain positioning

Differentials: cardiac tamponade (also obstructive shock, raised JVP ; but breath sounds equal bilaterally, muffled heart sounds, no hyperresonance), massive hemothorax (dull rather than hyperresonant), massive PE (no unilateral chest signs), simple pneumothorax without tension physiology.

Immediate decompression ; do not delay for imaging in a hemodynamically compromised patient.

• Needle decompression: large-bore cannula (14G) inserted into the pleural space:

  • Traditional site: 2nd intercostal space, mid-clavicular line

  • Alternative/increasingly preferred: 4th/5th intercostal space, anterior-to-mid axillary line (thinner chest wall, lower failure rate)

  • Release of hissing air confirms diagnosis and provides temporizing relief

  • Note: needle decompression has notable failure rates from inadequate needle length in some body habitus

• Finger thoracostomy: increasingly preferred in trauma/pre-hospital settings by trained providers ; blunt dissection into pleural space at the 4th/5th intercostal space anterior axillary line, more reliable than needle decompression, can be followed immediately by formal chest drain

• Formal chest drain (tube thoracostomy): definitive management following decompression ; inserted via the "triangle of safety" (anterior border of latissimus dorsi, lateral border of pectoralis major, line superior to nipple/5th intercostal space), connected to underwater seal drainage

• High-flow oxygen throughout

• If in cardiac arrest with tension pneumothorax suspected (or PEA arrest with chest trauma): bilateral finger thoracostomy as part of resuscitation ; a reversible cause to actively search for during ALS

Post-decompression: confirm resolution clinically and radiographically, monitor drain output and air leak, investigate underlying cause once stabilized.

Referral: cardiothoracic surgery if persistent air leak, underlying structural lung pathology, or recurrent tension pneumothorax; trauma team if traumatic etiology.