34.14 Entrapped Gasses

34.14.2 Explain the causes of barotrauma.

There are certain areas in the human body which can contain gas.  These are:

• Middle ear, behind the eardrum
• Sinuses 
• Stomach
• Tooth fillings 

With an increase in altitude and the corresponding decrease in pressure, any trapped gas tends to expand. 

As the air pressure increases again when we come back toward earth, any gas that is trapped will tend to contract, and create a vacuum. 

There will be an increase in pressure differential across the wall of whatever is trapping it and if it is large enough, can cause pain.

The sinuses are air spaces in the facial part of the skull bone, connected to the nasal passages.  

As with the eustachian tubes, the sinuses can more easily compensate in conditions of decreasing ambient pressure (climb) than increasing ambient pressure (descent).  When a person is suffering from a cold or the flu, the tissues at the nasal end of the sinuses become inflamed and swollen, again exacerbating the problem.