Pneumothorax

Disease class: Pleural diseases

Physiology

Each lung sits inside a sack called the pleura. The pleura are made of two layers: parietal (next to the rib cage) and visceral (next to the organ). There is a potential space between the layers.

 

Pathophysiology

There are three types of pneumothorax.

1. Primary: Spontaneous. Most likely in young, thin, significantly taller than average, males.
2. Secondary: Occurs as a result of underlying lung disease. E.g. COPD (70%).
3. Traumatic

A defect in the pleural layers or the lungs can allow air or fluids to enter the potential space and inflate it. Gas producing microorganisms can also inflate this space.

When air enters the potential space, the intrathoracic volume becomes occupied by this air. This reduces the volume available within the thorax.  The lungs need vacant space in which they can expand as they fill with air. The pressure from the pneumothorax collapses the affected lung.

Usually, the air is absorbed at a sufficient rate and the pneumothorax will resolve spontaneously.

 

Symptoms 

• Chest pain
• Dyspnoea

 

 

Investigations

• Chest radiograph

 

Compare with:

• Tension pneumothorax.  This is a severe form. It is a medical emergency.