Pneumothorax: Types & Causes

Instructor: Artem Cheprasov

Artem has a doctor of veterinary medicine degree.

There are many ways to classify a pneumothorax. This lesson teaches you about two major classifications, three large groupings, and their subtypes and causes.

What Helps Us Breathe?

If you ask someone how they are able to breathe, you'll get answers like:

  • 'Thanks to the lungs'
  • 'The diaphragm helps us inflate the lungs.'

Those are common responses. But what a lot of people do not think about is that the absence of something, rather than its presence, is a major factor in helping your lungs inflate and, thus, breathe.

Curious as to what we're missing and how it helps us breathe? You're about to find out, and that will help you understand why pneumothorax occurs.

What is Pneumothorax?

Pneumothorax is one of two major terms that refers to a collapsed lung. The other one is atelectasis. They are not the same process although they can be related to one another. That's beside the point of this lesson, however.

'Pneumo-' can mean air or lungs among other things. '-Thorax' means chest. So what pneumothorax means is that there is air in the chest. You might be thinking: 'Well of course there is, silly! That's how we breathe.'

However, there's a distinction between the air we inhale into our lungs and air in the chest itself. Yes, the lungs are in the chest. Nonetheless, when we say air in the chest, we are talking about a very specific part of the chest. That part is called the pleural space or pleural cavity. This is the space between the lungs and the inner chest wall. The absence of air in the pleural space creates a favorable pressure gradient that allows the lungs to expand and, thus, help you breathe. This is the absence we mentioned above.

The pleural space, also called the pleural cavity, is indicated in this image.
Pleural cavity

In other words, under normal conditions, the pressure within the lungs is higher than the pressure in the pleural space, and this allows the lungs to inflate. This is like inflating a balloon. The balloon is able to inflate, much like the lungs, only because as you blow into it, the pressure within the balloon is higher than the pressure around it.

If air enters the pleural space, the pressure outside the lung becomes greater than inside the lung, and the lung collapses. This would be like you taking your fist and squeezing on the balloon to let the air out as quickly as possible.

Note the pneumothorax on the left side of this image (right side of the chest). This is a large pneumothorax since the lung has collapsed into a fist-sized ball pointed out by the arrow. Compare both sides of the chest. The right side is blacker on x-ray because there is so much air relative to tissue matter. The left side of the chest (right side of the image) is much whiter (more opaque) since there is more soft tissue relative to gas when compared to the right side.

Types & Causes of Pneumothorax

There are several major types of pneumothorax and various causes for each. Each kind may result in a partial or total collapse of one or both lungs depending on circumstances.

As you go through these, note that there are two very general classifications of a pneumothorax--open and closed. An open pneumothorax occurs when air leaks into the chest via an open wound affecting the chest wall--think stab or gunshot wound. A closed pneumothorax occurs when the chest wall is intact. This can happen when a rib fracture punctures a lung or the lung itself is diseased and air escapes into the pleural space from the ruptured (burst) air sacs (alveoli) of the lungs.

With that in mind, there are three general types of pneumothorax:

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