The bends is a painflul condition that occurs in scuba divers who ascend too quickly or in aviators flying at high altitudes. Also called decompression sickness, the bends results when bubbles from dissolved gases form in the blood or in tissues because of rapidly decreasing pressure.


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Decompression sickness

Hyperbaric chamber

Scuba diving

The bends is also called decompression sickness or caisson * sickness. When a person is scuba diving, the water pressure increases with depth. As depth increases, the pressure of the air breathed also must increase. This causes more of the air to dissolve in the bloodstream.

How Is the Body Affected?

The main components of air are oxygen and nitrogen gases. Oxygen is continuously used by the body, but nitrogen is not used. When a diver ascends, the pressure decreases and the blood can no longer hold all the nitrogen dissolved in it.

* caisson (KAY-son) means a watertight container that divers or construction workers use under water.

If a diver ascends slowly, the nitrogen escapes into the lungs and is breathed out harmlessly. But if the diver ascends rapidly, the nitrogen forms bubbles in the blood that can lodge at joints such as the elbow or knee and cause pain. In severe cases, extreme pain causes the sufferer to double over, hence the common name "the bends."

Symptoms of the bends usually show up within 90 minutes of diving but may take as long as two days. Minor cases cause itching, rash, joint pain, or skin discoloration. Severe cases cause symptoms such as extreme pain at the joints, headache, seizures, hearing problems, nausea and vomiting, back or abdominal pain, vision disturbances, or chest pain.

How Do Doctors Treat the Bends?

Minor cases of the bends usually require no treatment, although a doctor should be consulted. Treatment of severe cases, however, requires a hyperbaric (hy-per-BARE-ik) chamber, a device that creates pressure to redissolve the gas bubbles. The patient is placed under high-pressure conditions, and then the pressure is slowly decreased. Prompt treatment increases the chances for a complete recovery.

What Do Scuba Divers Need to Know?

There are about 5 million people who scuba dive. Scuba divers must be certified and must take training classes, where they learn how to dive safely to avoid decompression sickness. The bends is a preventable condition when safety rules are followed strictly.

See also
Altitude Sickness


Marine Medical Systems, 84 North Main Street, South Norwalk, CT 06854. Marine Medical Systems posts a fact sheet about diving injuries and decompression sickness at its website.
Telephone 800-272-3008

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