Pneumothorax

From Ganfyd

Tension pneumothorax is a clinical diagnosis. Suspect in cases with suspected pneumothorax who demonstrate shock, hypotension and are in extremis. Emergency treatment with either a needle thoracocentesis or a thoracostomy is required, to be followed by a formal chest drain.

A pneumothorax refers to air in the pleural space.

Presentation

Right-sided spontaneous pneumothorax.

Different left-sided pneumothorax secondary to trauma.

Consider when ever sudden

• Dyspnoea
• Pleuretic chest pain

Can be asymptomatic

Causes

Always admit a secondary spontaneous pneumothorax and treat more aggressively than equivalent sized primary spontaneous pneumothorax. If familial history screen for Birt-Hogg-Dube syndrome

Spontaneous

Primary Spontaneous Pneumothorax

Pneumothorax in the absence of underlying lung disease. Mainly occur among tall, young, smoking males. These are not strictly idiopathic as they are often due to to leakage of air from apical blebs in lung.

Genetic associations

• Some mutations of the FLCN gene are associated with a highly increased incidence as in Birt-Hogg-Dube syndrome.
  • The renal malignancy risk comes on a mean of 10 years later than the pneumothorax so diagnosis may allow effective renal screening
• Marfan's syndrome
• Ehlers-Danlos syndrome
• Alpha-1 antitrypsin deficiency

Secondary Spontaneous Pneumothorax

Due to pre-existing pathology: eg

• Bullae in emphysema
• Interstitial lung disease

See a list of causes

Traumatic pneumothorax

• Traumatic; esp. penetrating trauma or blunt trauma causing rib fractures

Iatrogenic pneumothorax

• After fine needle lung aspiration (hint the CT lung can guide management here)
• Post-CABG or thoracotomy
• As a complication of central venous access or Thoracocentesis

Trapped lung

Trapped lung is when the lung can not expand fully due to an endobronchial obstruction or a thick visceral peel. This is not the same as a pneumothorax as the thoracic cavity is at less than atmospheric pressure.

Complications

• Tension pneumothorax
• Decompensation in patients with pre-existing poor respiratory reserve.

Diagnosis

Essentially radiological

• Chest X-ray
  • Expiratory films are not usually necessary but you will miss about 10% of (minor) pneumothoracies without them
  • The percentage pneumothorax should be calculated as:

%Pneumothorax = ((WidthHemithorax)³ − (WidthLung)³) / (WidthHemithorax)³ * 100

• CT chest is todays gold standard
  • Demonstrates complex and small pneumothoracies
  • Excludes conditions such as bullae

Treatment

Evacuation by aircraft may not be such a good idea - although one that occurs on an aircraft will reduce in size as you get closer to sea level

Detailed guidance is set out in the British Thoracic Society guidelines^[1]

Essentially, treatment depends on the underlying aetiology, the severity of symptoms and the size of the pneumothorax. Small, largely asymptomatic primary pneumothoraces may simply be observed with serial CXRs. Moderately sized ones may require aspiration of air and larger ones may require intercostal chest drains.

Recurrent Primary Pneumothoraces

• VATS pleurectomy and pleurodesis +/- bullectomy
• Pleurodesis is the intentional irritation of the pleural cavity to encourage it to obliterate and fuse. Chemicals that have been used include tetracycline and talc with graded talc being shown to be safe.
• Pleurectomy effectively results in fusion of the visceral surface of the lung directly to the chest wall.

References