- decompression sickness
aeroembolism (def. 2).[1940-45]
* * *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.
* * *physiological effects of the formation of gas bubbles in the body because of rapid transition from a high-pressure environment to one of lower pressure. Pilots of unpressurized aircraft, underwater divers, and caisson workers are highly susceptible to the sickness because their activities subject them to pressures different from the normal atmospheric pressure experienced on land.At atmospheric pressure the body tissues contain, in solution, small amounts of the gases that are present in the air. When a pilot ascends to a higher altitude, the external pressures upon his body decrease, and these dissolved gases come out of solution. If the ascent is slow enough, the gases have time to diffuse from the tissues into the bloodstream; the gases then pass to the respiratory tract and are exhaled from the body.Underwater (underwater diving) divers breathing compressed air are also faced with the possibility of a form of decompression sickness known as the bends. As they descend into the water, the external pressure increases proportionally to the depth. The compressed air that is breathed is equal in pressure to that of the surrounding water. The longer a diver stays down and the deeper the dive, the more compressed gas that is absorbed by the body. When the diver ascends, time must be allowed for the additional gases to be expelled slowly or they will form bubbles in the tissues.The major component of air that causes decompression maladies is nitrogen. The oxygen breathed is used up by the cells of the body and the waste product carbon dioxide is continuously exhaled. Nitrogen, on the other hand, merely accumulates in the body until the tissue becomes saturated at the ambient pressure. When the pressure decreases, the excess nitrogen is released.Nitrogen is much more soluble in fatty tissue than in other types; therefore, tissues with a high fat content (lipids) tend to absorb more nitrogen than do other tissues. The nervous system is composed of about 60 percent lipids. Bubbles forming in the brain, spinal cord, or peripheral nerves can cause paralysis and convulsions (divers' palsy), difficulties with muscle coordination and sensory abnormalities (divers' staggers), numbness, nausea, speech defects, and personality changes. When bubbles accumulate in the joints, pain is usually severe and mobility is restricted. The term bends is derived from this affliction, as the affected person commonly is unable to straighten joints.Small nitrogen bubbles trapped under the skin may cause a red rash and an itching sensation known as divers' itches. Usually these symptoms pass in 10 to 20 minutes. Excessive coughing and difficulty in breathing, known as the chokes, indicate nitrogen bubbles in the respiratory system. Other symptoms include chest pain, a burning sensation while breathing, and severe shock.Relief from decompression sickness usually can be achieved only by recompression in a hyperbaric chamber followed by gradual decompression, but this process is not always able to reverse damage to tissues.
* * *
Look at other dictionaries:
decompression sickness — n a sometimes fatal disorder that is marked by neuralgic pains and paralysis, distress in breathing, and often collapse and that is caused by the release of gas bubbles (as of nitrogen) in tissue upon too rapid decrease in air pressure after a… … Medical dictionary
decompression sickness — ► NOUN ▪ a serious condition that results when too rapid decompression causes nitrogen bubbles to form in the tissues of the body … English terms dictionary
decompression sickness — ☆ decompression sickness n. a condition caused by the formation of nitrogen bubbles in the blood or body tissues as the result of a sudden lowering of atmospheric pressure, as in deep sea divers, astronauts, and pilots ascending too quickly: it… … English World dictionary
Decompression sickness — Caisson disease [decompression sickness] Classification and external resources Two United States Navy sailors prepare for training inside a decompression chamber … Wikipedia
decompression sickness — 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 … Aviation dictionary
decompression sickness — Caisson disease Cais son dis*ease (Med.) A disease frequently induced by remaining for some time in an atmosphere of high pressure, as in caissons, diving bells, etc. It is characterized by neuralgic pains and paralytic symptoms. It is caused by… … The Collaborative International Dictionary of English
decompression sickness — noun A sometimes fatal condition resulting from the formation of nitrogen bubbles in the blood and tissues, because of too rapid decompression, seen especially in deep sea divers ascending rapidly from a dive. It is characterized by severe pains… … Wiktionary
decompression sickness — noun a condition that results when too rapid decompression causes nitrogen bubbles to form in the tissues of the body, characterized by pain in the muscles and joints, cramp, numbness, nausea, and paralysis … English new terms dictionary
decompression sickness — decom pression .sickness n [U] a dangerous medical condition that people get when they come up from deep under the sea too quickly = ↑the bends … Dictionary of contemporary English
decompression sickness — decom pression ,sickness noun uncount a serious medical condition that affects DIVERS who come up to the surface of water too quickly … Usage of the words and phrases in modern English