Pneumothorax

Description

• presence of free air in the intrapleural space (between parietal and viseral pleura)
• types:

1. Spontaneous (primary) pneumothorax.
   • Due to non-traumatic rupture of alveolous, bronchiole, or bleb
   • No underlying pulmonary pathology present
   • Often due to rupture of small subpleural cyst or bleb
   • Occurs primarily in young, healthy patients (ages 15-40yo), with tall and thin body habitus
2. Secondary spontaneous pneumothorax from underlying lung pathology
   • COPD, asthma, cystic fibrosis,
   • infections: necrotizing bacterial pneumonia, TB, fungal pneumonia, PCP
   • neoplasm
   • Interstitial lung disease: sarcoid, pulmonary fibrosis, pneumoconioses
3. Trauma
   • broken rib, ruptures bronchus, blunt trauma, penetrating wound, etc.
4. Iatrogenic
   • central line placement, etc
   • seen in ~3% of ICU patients
5. "Tension pneumothorax"
   • Air continues to enter pleural space through broncoalveolar disruption and becomes trapped via ball-valve mechanism
   • Intraplural pressure then increases
   • venous return to right heart decreases, resulting in decreased cardiac output
   • mediastinum can shift toward uninvolved side, which further interferes with right atrial filling. May note tracheal deviation as well.
   • V/Q mismatch results in hypoxia

• Signs and Symptoms

1. severity of symptoms is proportional to the size of the pneumothorax
2. ipselateral pleuritic chest pain, cough, dyspnea, referred pain to shoulder
3. rapid, shallow breathing
4. moderate to severe: profound respiratory distress, hypotension, shock, cyanosis

• Diagnosis

1. drop in oxygen saturation may be first indicator
2. Upright chest X-ray

• absence of lung markings distal or peripheral to the visceral pleaural white line
  
• displacement of mediatinum
• "Deep sulcus sign"= on a supine chest radiograph is an indication of a pneumothorax. In a supine film, it may be the only indication of a pneumothorax because air collects anteriorly and basally, within the nondependent portions of the pleural space as opposed to the apex (of the lung) when the patient is upright. The costophrenic angle is abnormally deepened when the pleural air collects laterally, producing the deep sulcus sign. (See * on image below)
• Chest CT-- very sensitive for small pneumothorax, but has little practical advantage over CXR.
• 

• Treatment
  
  1. Cardiac monitoring, pulse ox, oxygen 100% via nonrebreather face mask, IV access
  2. Nontraumatic pneumothorax estimated at <15% collapse and no cardiovascular or respiratory compromise can be observed with 100% oxygen support
     
     • consider simple aspiration if increase in size of pneumothorax (still 155- 30%) is noted during observation.  Place aspiration catheter (usually 8 Fr) with 3-way stopcock.  Aspirate air until resistance or 3L aspirated.  If no pneumothorax is visible on two CXRs taken 4 hours apart, then the catheter can be removed.  Repeat CXR 2 hours after catheter removed to see if pneumothorax has recurred.  Consider Hemlich valve or suction if simple aspirationis unsuccessful.
  3. Suspected tension pneumothorax requires immediate needle thoracostomy or chest tube is indicated in an unstable patient
     
     • 14 to 18 guage angiocatheter is placed in second intercostal space at the midclavicular line, or at the 4th or 5th intercostal space at the anterior axillary line.
     • Video:
       http://www.youtube.com/watch?v=4cuotNQPRNc#

      

  4. Chest tube

• Indications: pneumothorax with >30% collapse or cardiovascular instability
• is the definitive therapy after needle thoracostomy
• required if pneumothorax of any size in a patient receiving positive pressure ventilation
• tube size:
  
  • small caliber (7-14 Fr) tube for spontaneous pneumothorax
  • 20-28 Fr for secondary spontaneous pneumothorax
  • 28 Fr when there is detectable pleural fluid or anticipated need for mechanical ventilation
• Following insertion, the tube should be connected to a water-seal device
• Video:
  http://www.youtube.com/watch?v=QM85GdT4ZVY&feature=related

References:

1. Baumann MH, Strange C, Heffner JE, et al. Management of spontaneous pneumothorax. Chest. 2001; 119:590. S193.

2. Sahn SA. Spontaneous pneumothorax. New England Journal of Medicine. 2000; 342:868.

3. Light RW. Pleural Diseases. 4th edition. Lippincott, Williams & Wilkins. 2001.