34.16 Decompression Sickness

34.16.2 Explain the causes of decompression sickness.

Decompression sickness (DCS) occurs when a person is exposed to a rapid reduction in surrounding pressure.

Under increased pressure, such as during scuba diving, more nitrogen dissolves into the body's blood and tissues.

If the surrounding pressure is then reduced too quickly, such as by:

• ascending rapidly from a dive; or

• flying at altitude too soon after diving,

the dissolved nitrogen may come out of solution and form bubbles within the body.

These nitrogen bubbles most commonly affect the:

• joints and muscles, causing pain known as the bends; and

• bloodstream, where they may interfere with normal circulation.

Less commonly, nitrogen bubbles may affect the:

• skin, causing itching or mottling — the creeps;

• nervous system, causing dizziness, weakness, loss of coordination or paralysis — the staggers; or

• lungs, causing chest pain, coughing or difficulty breathing — the chokes.

The risk increases when the reduction in pressure is rapid, because the body has insufficient time to eliminate the excess nitrogen normally through the lungs.

34.16.4 Describe the symptoms of decompression sickness.