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decompression sickness,physiological disorder caused by a rapid decrease in atmospheric pressure, resulting in the release of nitrogen bubbles into the body tissues. It is also known as caisson disease, altitude sickness, and the bends. It is an occupational hazard of persons who work under greatly increased atmospheric pressure below the surface of the earth (e.g., divers and laborers who work under compressed air) when their return to normal atmospheric pressure is made too quickly. When the body is subjected to high atmospheric pressure the respiratory gases are compressed and larger amounts are dissolved in the body tissues. During ascent from depths greater than 30 ft (9.1 m), these gases escape as the external pressure decreases. Airplane pilots who go rapidly from normal atmospheric pressure to high altitudes (low atmospheric pressure) in unpressurized aircraft or in aircraft with faulty pressurizing apparatus also encounter the disorder. The decrease in air pressure releases body nitrogen in the form of gas bubbles that block the small veins and arteries and collect in the tissues, cutting off the oxygen supply and causing nausea, vomiting, dizziness, pain in the joints and abdomen, paralysis, and other neurological symptoms. In severe cases there may be shock, total collapse, and, if treatment is not prompt, death. Persons who work under increased atmospheric pressure must make the ascent to normal atmospheric pressure gradually, often through pressurized chambers, a procedure that allows the nitrogen to be released slowly from the blood and expired from the lungs. Inhalation of pure oxygen aids in clearing nitrogen from the body. Those who suffer symptoms of decompression sickness at high altitudes (commonly called aeroembolism) experience relief on returning to an atmospheric pressure normal to them; this and oxygen inhalation will usually effect recovery.
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A sickness caused by the evolution of nitrogen bubbles in the body as a result of the effects of reduced atmospheric pressure. Normal symptoms of decompression sickness are the bends, chokes, creeps, unconsciousness, and neurological symptoms. It can be potentially fatal if the original higher pressure is not restored. Fighter crews use pressure suits and pressure breathing to avoid the effects of decompression sickness. Also called aeroembolism, the bends, and caisson disease.
An Illustrated Dictionary of Aviation Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved
decompression sickness, illness
a disorder characterized by severe pain in muscles and joints, cramp, and difficulty in breathing, caused by a sudden and sustained decrease in air pressure, resulting in the deposition of nitrogen bubbles in the tissues
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005