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Definition: decompression sickness from The Hutchinson Unabridged Encyclopedia with Atlas and Weather Guide

Illness brought about by a sudden and substantial change in hydrostatic pressure. It is caused by a too rapid release of nitrogen that has been dissolved into the bloodstream under pressure; when the nitrogen forms bubbles it causes the bends. The condition causes breathing difficulties, joint and muscle pain, and cramps, and is experienced mostly by divers who surface too quickly.

After a one-hour dive at 30 m/100 ft, 40 minutes of decompression are needed, according to US Navy tables.


Summary Article: decompression sickness
from The Columbia Encyclopedia

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.

The Columbia Encyclopedia, © Columbia University Press 2018

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Full text Article decompression sickness (or caisson disease)
The Macmillan Encyclopedia

An occupational hazard of pilots and underwater divers caused by too rapid a return to normal atmospheric pressure. At high pressures...

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