Tension pneumothorax

Background

• Pneumothorax with ongoing air leak creating a one-way valve mechanism → progressive accumulation of air under pressure in the pleural space
• Causes mediastinal shift, compression of contralateral lung, and impaired venous return → obstructive shock → cardiac arrest
• Death occurs from impaired venous return and hypoxia — this is a clinical diagnosis treated immediately without waiting for imaging
• Causes: penetrating or blunt thoracic trauma, mechanical ventilation (barotrauma), central line placement, spontaneous pneumothorax with valve mechanism

Clinical Features

• Unilateral diminished or absent breath sounds
• Hypotension or hemodynamic instability (obstructive shock — impaired RV filling)
• Distended neck veins (may not occur if patient is hypovolemic)
• Contralateral tracheal deviation (late finding — do not wait for this)
• Tachycardia, tachypnea, hypoxia
• Cardiac arrest (PEA or asystole) — always consider tension pneumothorax in traumatic arrest

Differential Diagnosis

Pneumothorax Types

The pleural cavity is normally a potential space, in which air collects in a pneumothorax.

• Tension pneumothorax
• Spontaneous pneumothorax
  • Catamenial pneumothorax
• Traumatic pneumothorax
  • Iatrogenic pneumothorax

Thoracic Trauma

• Airway/Pulmonary
  • Bronchial injury
  • Diaphragmatic trauma
  • Hemothorax
  • Pneumomediastinum
  • Pulmonary contusion
  • Tracheal injury
  • Trachobronchial injury
  • Traumatic pneumothorax
    • Tension pneumothorax
• Cardiac/Vascular
  • Cardiac injury
    • Blunt cardiac injury
      • Cardiac contusion
      • Commotio cordis
    • Penetrating cardiac injury
    • Cardiac tamponade
  • Traumatic aortic transection
• Musculoskeletal
  • Clavicle fracture
    • Clavicle fracture (peds)
  • Rib fracture
    • Flail chest
  • Scapular fracture
  • Scapulothoracic dissociation
  • Sternoclavicular dislocation
  • Sternum fracture
  • Thoracic and lumbar fractures and dislocations
• Other
  • Esophageal injury or Perforation
  • Pneumomediastinum
  • Pneumopericardium
  • Traumatic asphyxia

Evaluation

Left sided tension pneumothorax with mediastinal shift

This is a clinical diagnosis — do NOT delay treatment for imaging

• CXR (if time permits and patient is stable): mediastinal shift, unilateral hyperlucency, deep sulcus sign
• Lung ultrasound: absent lung sliding on affected side (rapid bedside confirmation)

Lung ultrasound of pneumothorax

• No lung sliding seen (not specific for pneumothorax)
• May also identify "lung point": distinct point where you no longer see lung sliding (pathognomonic)
• Absence of lung sliding WITHOUT lung point could represent apnea or right mainstem intubation
• Evaluate other intercostal spaces because pneumothorax may only be seen in least dependent area of thorax
  • NO comet tail artifact
  • Bar Code appearance/"Stratosphere" sign on M-mode (absence of "seashore" waves)
• Ultrasound has greater sensitivity than chest x-ray for pneumothorax in trauma patients

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Management

Immediate Decompression

• Needle thoracostomy (decompression) — temporizing measure:
  • 14-gauge angiocatheter, 2nd intercostal space midclavicular line (traditional)
  • Evidence suggests 4th-5th intercostal space at anterior axillary line has lower failure rate (less chest wall thickness)
  • Failure rate with standard needle is up to 50% in obese or muscular patients
• Finger thoracostomy — more reliable than needle decompression:
  • 4th-5th intercostal space, anterior axillary line
  • Make incision through skin and intercostal muscles, bluntly enter pleural space with finger
  • Preferred in cardiac arrest or when needle decompression fails
• Always followed by chest tube placement (needle/finger alone is not definitive)

Chest Tube

• Adult: 28-36 Fr
• Pediatric: Estimated as 4 × ETT size (ETT = 4 + age/4)

Adult Chest Tube Sizes

Chest Tube Size	Type of Patient	Underlying Causes
Small (8-14 Fr)	Most spontaneous pneumothorax (primary and secondary) Most iatrogenic pneumothorax	Alveolar-pleural fistulae (small air leak) Iatrogenic air
Medium (20-28 Fr)	Traumatic pneumothorax Traumatic hemothorax ("any acute hemothorax visible on chest radiograph") Pneumothorax on mechanical ventilation Non-traumatic tension pneumothorax Malignant effusion	Trauma/bleeding (hemothorax/hemopneumothorax) Bronchial-pleural fistulae (large air leak) Malignant fluid
Large (36-40 Fr)	Empyema	Thick pus

Disposition

• Admit all patients after chest tube placement
• ICU if hemodynamically unstable or on mechanical ventilation

Special Instructions

Flying

• Can consider flying 2 weeks after full resolution of traumatic pneumothroax

Complications

• Reexpansion pulmonary edema (rare but serious)
• Tube malposition or dislodgement

See Also

• Pneumothorax (main)
• Needle thoracostomy
• Finger thoracostomy
• Chest tube
• Traumatic arrest