caisson disease

decompression sickness

 also called the bends or caisson disease

Harmful effects of rapid change from a higher- to a lower-pressure environment. Small amounts of the gases in air are dissolved in body tissues. When pilots of unpressurized aircraft go to high altitudes or when divers breathing compressed air return to the surface, external pressure on the body decreases and the gases come out of solution. Rising slowly allows the gases to enter the bloodstream and be taken to the lungs and exhaled; with a quicker ascent, the gases (mostly nitrogen) form bubbles in the tissues. In the nervous system, they can cause paralysis, convulsions, motor and sensory problems, and psychological changes; in the joints, severe pain and restricted mobility (the bends); in the respiratory system, coughing and difficulty breathing. Severe cases include shock. Recompression in a hyperbaric chamber followed by gradual decompression cannot always reverse tissue damage.

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caisson disease [′kā‚sän di‚zēz]

(medicine)

A condition resulting from a rapid change in atmospheric pressure from high to normal, causing nitrogen bubbles to form in the blood and body tissues. Also known as bends; compressed-air illness.