Decompression sickness, also commonly known as the bends or caisson disease, is an ailment caused by a sudden decrease in air or water pressure outside of the body. This can occur in a variety of situations, but the most common are when a diver decreases depth too quickly, or a diver flies right after diving, or a plane without pressure control goes upwards too quickly, or someone leaves a high pressure environment (such as a mine). In either case, the results can be very serious or even fatal.
What makes this sudden depressurization dangerous is that it can cause gases that are normally dissolved in the body to come out of the fluid and collect into bubbles. This effect can be demonstrated by opening a can or bottle of soda. The loud hissing sound is the rapid escape of carbon dioxide gas that was once dissolved in the liquid.
Most of the gas that is released during decompression is nitrogen, which can be dangerous if it collects in too large a quantity. If a bubble forms in the blood, it can stop blood flow to or through vital organs and result in extreme pain or death.
Luckily, a cure for this problem is for recompression to occur by increasing the pressure around the body while breathing pure oxygen. Decompression chambers can be used for this, although they are normally used to gradually decrease pressure to acclimate the body to normal air pressure.
The symptoms of decompression sickness are commonly localized pain, particularly around joints, nausea, confusion, headaches, fatigue, seizures, tingling or stinging sensations, paralysis, incontinence, shortness of breath, coughing, and swelling of the skin. If these symptoms are noticed after diving or while on a plane, medical assistance should be sought immediately. Sometimes the problem goes away on its own, such as when a plane makes its descent.
Prevention of decompression sickness is fairly simple, as long as care is taken. When diving, make decompression stops at appropriate depths to allow your body to stabilize. When flying without a pressurized cabin, make a slower ascent to allow your body to adjust. Decompression sickness has even afflicted construction workers that work on tall buildings or bridges.