B3 1.6 Artificial breathing aids

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There are many different reasons why people sometimes struggle to breathe and get enough oxygen into their lungs. For example:

  • The tubes leading to the lungs may be very narrow so less air gets through to them.
  • The structure of the alveoli can break down. This results in a few big air sacs that have a similar surface area for gas exchange than healthy alveoli.
  • Some people are paralysed in an accident or by disease so they can't breathe.

There are a number of artificial aids for supportingor taking over breathing that have saved countless lives. They work in two main ways - negative pressure and positive pressure.

The 'iron lung' - negative pressure

Polio is a disease that can leave people paralysed and unable to breathe. To keep polio sufferers alive until their bodies recovered, an exertnal negative - pressure ventilator was developed. This was commonly known as the iron lung. Nowadays we are all vaccinated against polio and it has almost been wiped out worldwide.

The patient lay in a metal cylinder with their head sticking out and a tight seal around the neck. Air was pumped out of the chamber, lowering the pressure inside to form a vacuum. As a result, the chest wall of the patient moved


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