Divers who have experienced pressures greater than 2 atmospheres absolute may develop decompression sickness if they ascend too rapidly. Decompression sickness may be mild, with only limb and joint pain ("bends," type 1), or serious, with neurologic and pulmonary manifestations (type 2). Most serious are symptoms of medullary involvement with development of paraparesis. Divers with a patent foramen ovale are more liable to develop decompression sickness than divers without a patent foramen ovale. Treatment in a pressure chamber is essential for recovery, and detailed decompression tables are used to prevent decompression sickness.
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• Decompression sickness usually occurs during rapid ascent from depth after diving but may also occur in rapid ascent to high altitudes from sea level.
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• Systemic manifestations may involve the nervous system.
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• Decompression sickness can be avoided by gradual ascent, and if it occurs, it is treated by hyperbaric recompression.
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• Hyperbaric oxygen has been found to be useful in treating decompression sickness with neurologic manifestations.
Historical note and terminology
Decompression sickness is one of several dysbarisms, ie, disturbances in the human body resulting from a change in atmospheric pressure. Divers and compressed air tunnel workers have experienced that if they adjust too quickly to the normal environmental pressure, they will develop a variety of unpleasant symptoms, and that these can be prevented by a slower ascent or by hyperbaric recompression. Rapid ascent to high altitudes in an aircraft with an uncompressed cabin can produce similar symptoms. The first and least severe symptoms are characterized by limb and joint pain. Thereafter, or with more rapid ascent or decompression, other nervous system symptoms will occur.
The condition was well known among miners and tunnel workers, and it was, therefore, called "caisson disease." Other terms used to describe the condition are "the bends" (limb and joint pain), "the chokes," and "hits."