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Revision as of 06:34, 29 September 2003 by Fuzheado (talk | contribs) (added more on Brooklyn Bridge and effects)(diff) ← Previous revision | Latest revision (diff) | Newer revision → (diff)The bends (properly called decompression sickness, see DCI) is a condition experienced by anyone going from high pressure to lower pressure, and is typically experienced by divers who ascend too quickly from depths below 10 meters.
When air under high pressure is breathed for any length of time, nitrogen dissolves in the body fluids. When moving to lower pressure, this causes the gas to come back out of solution, and forms bubbles in the blood. The physiologist J.S. Haldane studied this problem in the early 20th century, eventually devising the method of staged, gradual decompression, whereby the pressure on the diver is released slowly enough that the nitrogen comes gradually out of solution without forming bubbles. Repeated cases decompression sickness can lead to brittle bones, and severe cases can lead to death.
Because helium has a far lower solubility in water, deep-sea divers nowadays breathe heliox (helium/oxygen mix).
An alternative name is caisson disease; this name comes from the 19th century, when large engineering excavations (bridges, tunnels) required the work to be done in "caissons" under pressure to keep water from flooding the excavations. This was a major factor for laborers working on the Brooklyn Bridge, and incapacitated the project leader Washington Roebling.
See also: other ill effects experienced by divers are nitrogen narcosis and oxygen toxicity.