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Pneumothorax

Changed by Craig Hacking, 5 Feb 2019
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Pneumothorax refers to the presence of gas (air) in the pleural space. When this collection of gas is constantly enlarging with resulting compression of mediastinal structures, it can be life-threatening and is known as a tension pneumothorax. For those pneumothoraces occurring in neonates see the article on neonatal pneumothorax.

Epidemiology

There are many causes of pneumothorax which makes it impossible to generalise the epidemiology. However, primary spontaneous pneumothoraces occur in younger patients (typically less than 35 years of age) whereas secondary spontaneous pneumothoraces occur in older patients (typically over 45 years of age) 4. 

Clinical presentation

Presentation is variable and may range from no symptoms to severe dyspneadyspnoea with tachycardia and hypotension. In patients who have a tension pneumothorax, presentation may be with distended neck veins and tracheal deviation, cardiac arrest and in the most severe cases, death.

It is interesting to note that some generalisations can be made in regards to the clinical presentation in primary versus secondary spontaneous pneumothoraces:

  • primary spontaneous: pleuritic chest pain usually present, dyspnoea mild or moderate
  • secondary spontaneous: pleuritic chest pain often absent, dyspnoea usually severe

Pathology

It is useful to divide pneumothoraces into three categories 4:

  • primary spontaneous: no underlying lung disease
  • secondary spontaneous: underlying lung disease is present
  • iatrogenic/traumatic
Primary spontaneous

A primary spontaneous pneumothorax is one which occurs in a patient with no known underlying lung disease. Tall and thin people are more likely to develop a primary spontaneous pneumothorax. There may be a familial component, and there are well-known associations 10:

Secondary spontaneous

When the underlying lung is abnormal, a pneumothorax is referred to as secondary spontaneous. There are many pulmonary diseases which predispose to pneumothorax including:

Iatrogenic/traumatic

Iatrogenic/traumatic causes include 1-4:

  • iatrogenic:
    • percutaneous biopsy
    • barotrauma, ventilator
    • radiofrequency (RF) ablation of lung mass
    • endoscopic perforation of the oesophagus
  • trauma:
Others
  • pneumoperitoneum with passage through congenital/acquired diaphragmatic defects

Radiographic features

Plain radiograph

A pneumothorax is, when looked for, usually easily appreciated. Typically they demonstrate:

  • visible visceral pleural edge is seen as a very thin, sharp white line
  • no lung markings are seen peripheral to this line
  • peripheral space is radiolucent compared to the adjacent lung
  • lung may completely collapse
  • mediastinum should not shift away from the pneumothorax unless a tension pneumothorax is present (discussed separately)
  • subcutaneous emphysema and pneumomediastinum may also be present

In cases where these features are not clearly present a number of techniques can be employed:

  • lateral decubitus radiograph:
    • should be done with the suspected side up
    • the lung will then 'fall' away from the chest wall
  • expiratory chest radiograph:
    • lung becomes smaller and denser
    • pneumothorax remains the same size and is thus more conspicuous: although some authors suggest that there is no difference in detection rate 6
  • CT scan

When imaged supine detection can be difficult: see pneumothorax in a supine patient, and pneumothorax is one cause of a transradiant hemithorax.

Ultrasound

M-mode can be used to determine movement of the lung within the rib-interspace. Small pneumothoraces are best appreciated anteriorly in the supine position (gas rises) whereas large pneumothoraces are appreciated laterally in the mid-axillary line.

See: ultrasound for pneumothorax.

CT

Provided lung windows are examined, a pneumothorax is very easily identified on CT, and should pose essentially no diagnostic difficulty. When bullous disease is present, a loculated pneumothorax may appear similar.

Treatment and prognosis

Treatment depends on a number of factors:

  • size of the pneumothorax
  • symptoms
  • background lung disease/respiratory reserve

Estimating the size of pneumothorax is somewhat controversial with no international consensus. CT is considered more accurate than plain radiograph.

  • British Thoracic Society (BTS) guidelines (2010): measured from chest wall to lung edge at the level of the hilum 12
    • <2 cm: small
    • ≥2 cm: large
  • American College of Chest Physicians guidelines (2001): measured from thoracic cupola to lung apex 13
    • <3 cm: small
    • ≥3 cm: large

These can be used together to determine the best course of action. The following is based on the BTS guidelines 12 for the treatment of pneumothorax; local protocols may differ:

  • asymptomatic small rim pneumothorax: no treatment with follow-up radiology to confirm resolution
  • pneumothorax with mild symptoms (no underlying lung condition): needle aspiration in the first instance
  • pneumothorax in a patient with background chronic lung disease or significant symptoms: intercostal drain insertion (small drain using the Seldinger technique)

In patients with recurrent pneumothoraces or who are at very high risk of having recurrent events and have a poor respiratory reserve, a pleurodesis can be performed. This can either be medical (e.g. talc poudrage) or surgical (e.g. VATS pleurectomy, pleural abrasion, sclerosing agent) 4.

Differential diagnosis

Usually, the diagnosis is straightforward, but occasionally other entities should be considered:

  • artifacts: air caught between structures outside the chest
    • skin fold:
      • the apparent pleural edge is denser and (i.e. black) compared to a true PTX which is a white pleural edge
      • may be seen extending beyond the chest cavity or seen to fade out
    • clothing
    • blankets
  • monitoring leads (although these should be obvious)
  • overlapping breast margin
  • normal anatomical structures, e.g. medial border of the scapula
  • pulmonary bullae
  • giant bullous emphysema: differentiated from tension pneumothorax by clinical stability, interstitial vascular markings projected with the bullae and lack of hemithorax re-expansion following the insertion of an intercostal catheter
  • calcified pleural plaques
  • other gas in abnormal locations
  • other causes of a hyperlucent hemithorax
  • on CT
    • gas in a brachiocephalic vein from cannulation
    • beam-hardening artifact from concentrated iodinated contrast in a brachiocephalic vein or the SVC

See also

  • -<p><strong>Pneumothorax</strong> refers to the presence of gas (air) in the <a href="/articles/pleural-space">pleural space</a>. When this collection of gas is constantly enlarging with resulting compression of mediastinal structures, it can be life-threatening and is known as a <a href="/articles/tension-pneumothorax">tension pneumothorax</a>. For those pneumothoraces occurring in neonates see the article on <a href="/articles/neonatal-pneumothorax">neonatal pneumothorax</a>.</p><h4>Epidemiology</h4><p>There are many causes of pneumothorax which makes it impossible to generalise the epidemiology. However, primary spontaneous pneumothoraces occur in younger patients (typically less than 35 years of age) whereas secondary spontaneous pneumothoraces occur in older patients (typically over 45 years of age) <sup>4</sup>. </p><h4>Clinical presentation</h4><p>Presentation is variable and may range from no symptoms to severe dyspnea with tachycardia and hypotension. In patients who have a <a href="/articles/tension-pneumothorax">tension pneumothorax</a>, presentation may be with distended neck veins and tracheal deviation, cardiac arrest and in the most severe cases, death.</p><p>It is interesting to note that some generalisations can be made in regards to the clinical presentation in primary versus secondary spontaneous pneumothoraces:</p><ul>
  • +<p><strong>Pneumothorax</strong> refers to the presence of gas (air) in the <a href="/articles/pleural-space">pleural space</a>. When this collection of gas is constantly enlarging with resulting compression of mediastinal structures, it can be life-threatening and is known as a <a href="/articles/tension-pneumothorax">tension pneumothorax</a>. For those pneumothoraces occurring in neonates see the article on <a href="/articles/neonatal-pneumothorax">neonatal pneumothorax</a>.</p><h4>Epidemiology</h4><p>There are many causes of pneumothorax which makes it impossible to generalise the epidemiology. However, primary spontaneous pneumothoraces occur in younger patients (typically less than 35 years of age) whereas secondary spontaneous pneumothoraces occur in older patients (typically over 45 years of age) <sup>4</sup>. </p><h4>Clinical presentation</h4><p>Presentation is variable and may range from no symptoms to severe dyspnoea with tachycardia and hypotension. In patients who have a <a href="/articles/tension-pneumothorax">tension pneumothorax</a>, presentation may be with distended neck veins and tracheal deviation, cardiac arrest and in the most severe cases, death.</p><p>It is interesting to note that some generalisations can be made in regards to the clinical presentation in primary versus secondary spontaneous pneumothoraces:</p><ul>
  • -<li>skin fold: the apparent pleural edge is denser and may be seen extending beyond the chest cavity or seen to fade out</li>
  • +<li>skin fold:<ul>
  • +<li>the apparent pleural edge is denser (i.e. black) compared to a true PTX which is a white pleural edge</li>
  • +<li>may be seen extending beyond the chest cavity or seen to fade out</li>
  • +</ul>
  • +</li>

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