Barotrauma

Entrapped Gases

Barotrauma is pain or injury which can result from excessive pressure differences caused by changes in atmospheric pressure.

There are several areas in the body where gas can become trapped, including:

• the middle ear, behind the eardrum;
• the sinuses;
• the stomach and intestines; and
• around tooth fillings.

As altitude increases and atmospheric pressure decreases, trapped gas tends to expand.

During descent, atmospheric pressure increases and trapped gas tends to contract.

If the pressure cannot equalise, a pressure difference develops across the surrounding tissue, which can cause pain and, in severe cases, injury.

Barotrauma can occur during either a climb or descent, although problems with the middle ear and sinuses are more common during descent.

The Eustachian Tube

The Eustachian tube connects the middle ear to the back of the throat.

It allows air to pass between the middle ear and the throat so that the pressure on each side of the eardrum can equalise.

During a climb, expanding air in the middle ear normally escapes relatively easily through the Eustachian tube.

During a descent, the increasing outside pressure may make equalisation more difficult. This can cause the eardrum to be pushed inwards and produce pain.