21st February 2025

Pneumothorax

Pneumothorax is the presence of air in the pleural space (between the visceral and parietal pleura). 

Definitions

Pneumothorax is normally categorised by the underlying cause, as this determines management.

Table 8 Categorising pneumothorax

The most common cause of an iatrogenic pneumothorax is central line insertion. Other causes include lung biopsy, thoracocentesis and mechanical ventilation.

Risk factors for pneumothorax

Table 9 Risk factors for spontaneous pneumothorax

Presentation of pneumothorax

Pneumothorax frequently develops with minimal symptoms or may even be asymptomatic. Symptoms are usually sudden onset and include pleuritic chest pain and shortness of breath. Symptoms are normally more severe in secondary pneumothorax even with pneumothoraces of the same size.

Signs of pneumothorax on examination include reduced breath sounds and hyperresonant percussion notes on the side of the pneumothorax. Hypoxia is often not present in small primary spontaneous pneumothorax but may be present in secondary or traumatic pneumothorax. In traumatic pneumothorax, examination may reveal evidence of rib fractures or penetrating trauma.

Investigation of pneumothorax

The first-line investigation in suspected pneumothorax is an erect chest X-ray. 

CT chest should be considered if the diagnosis remains uncertain or in the context of chest trauma. CT can be helpful in differentiating pneumothorax from bullous lung disease, identifying underlying lung pathology, and accurately determining pneumothorax size.

Image Source: Wikimedia Commons (2010). Expiration-left-side-pneumo, Licensed under a creative commons licence. Available for free at: https://commons.wikimedia.org/wiki/File:Expiration-left-side-pneumo.jpg#/media/File:Expiration-left-side-pneumo.jpg (Accessed: 19 January 2024).

Management of pneumothorax

Traumatic pneumothorax should be referred to thoracic surgeons and monitored closely, as there is a risk of developing a tension pneumothorax.

Spontaneous pneumothorax management depends on several factors, including:

• Size: rim of air between lung and chest wall at the level of the hilum (small <2 cm, large >2 cm) (Figure 1)
• Symptom severity
• Pneumothorax type (primary spontaneous/secondary spontaneous)

As per British Thoracic Society (BTS) guidelines:

Table 10 Management of pneumothorax

Bilateral pneumothorax is potentially life-threatening and should proceed straight to bilateral chest drain insertion.

Follow up

Smoking cessation is important to reduce risk of recurrence.

In some cases, surgical intervention via VATS or thoracotomy may be advised to prevent recurrence. Chemical pleurodesis can also be considered.

Flying should be avoided until full resolution of the pneumothorax. Patients should be advised to avoid underwater diving permanently following a pneumothorax unless they have definitive surgical management. 

Tension pneumothorax

Tension pneumothorax is a medical emergency. It occurs when a one-way valve develops between the pleural cavity and the external environment, leading to progressive entry of air into the pleural space during inspiration, which is unable to be expelled. The resultant increase in intrathoracic pressure leads to reduced venous return, impaired cardiac output and haemodynamic collapse. 

Differences in presentation and management of tension pneumothorax compared to other types of pneumothorax are outlined below:

Table 11 Features, investigations and management of tension pneumothorax

References

• MacDuff A, Arnold A, Harvey J. Management of spontaneous pneumothorax: British Thoracic Society pleural disease guideline 2010. Thorax [Internet]. 2010 Aug 1 [cited 2022 Jan 31];65(Suppl 2):ii18–31. Available from: https://thorax.bmj.com/content/65/Suppl_2/ii18
• Bennett J, Vella C, Umerah O. Pneumothorax [Internet. BMJ Best Practice. 2021. Available from: https://bestpractice.bmj.com/topics/en-gb/3000083
• Lee YG. Pneumothorax in adults: Epidemiology and etiology [Internet]. Broaddus C, Finlay G, editors. Uptodate.com. 2020 [cited 2022 Jan 31]. Available from: https://www.uptodate.com/contents/pneumothorax-in-adults-epidemiology-and-etiology