Decompression sickness (DCS) occurs when the body is subjected to a sudden reduction in surrounding pressure. DCS occurs most frequently during deep sea diving or when flying in a nonpressurized aircraft.

DCS is caused by the formation of gas bubbles in the blood and tissues. At normal altitudes, nitrogen and other gases are exhaled or dissolved in the blood and tissues. However, during severe changes in altitude and air pressure, nitrogen and other gases form gas bubbles. These bubbles block the flow of blood. This condition can be fatal if not treated quickly.

A risk factor is something that increases your chance of getting a disease or condition. The only risk factor for decompression sickness is a sudden reduction in pressure. This occurs as a result of:

• Rising too quickly to the surface from deep sea scuba diving
• A fast ascent into a high altitude from a low altitude
• Sudden exit from a high pressure or hyperbaric chamber
• Increased risk with increased depth of dive
• Long duration of dive
• Multiple dives in one day
• Flying after diving
• Diving in cold water
• Fatigue
• Exertion
• Dehydration
• Obesity
• Increased age

The less severe type of DCS is called DCS I. It primarily results in inflammation of muscles, joints, and tendons, resulting in pain and swelling. This is commonly referred to as "the bends." Although pain may occur anywhere in the body, it is most common in or near an arm or leg joint. The pain may become more severe over time. Itching, skin mottling, weakness, and fatigue also occur.

The more severe type of DCS is called DCS II. This results in more serious systemic effects, including neurological symptoms such as numbness and tingling. In the most severe form, numbness may lead to paralysis and even death. Other symptoms of DCS II include:

• Stomach pain
• Back pain
• Headache
• Dizziness
• Confusion
• Visual disturbances
• Vertigo
• Chest pain and severe coughing (rarely)
• Shock

In situations where an individual dives occupationally and has regular exposure to increased pressure, a mild, chronic case of the bends may occur without detection. Over time, this can result in deterioration of affected joints and bones.

The doctor will ask about your symptoms and medical history, and perform a physical exam. When decompression sickness is suspected (based on the presence of classic symptoms and a history of recent diving, for example), treatment is often started immediately, without any delay for examination or testing. Blood and other diagnostic tests are not usually helpful.

If you experience symptoms of DCS, it is extremely important to get treatment immediately. In severe cases, delayed treatment may be fatal.

If you have DCS I, breathing 100% oxygen from a mask may be sufficient treatment. You should also be monitored carefully for the initiation of any other symptoms.

The treatment for DCS II is oxygen therapy in a hyperbaric chamber. This device works by gradually increasing and then decreasing air pressure around the body, which forces gas bubbles to dissolve. Oxygen should be administered through an oxygen mask during transport to a hyperbaric chamber.

Treatment should be given even if initial symptoms are mild or disappear. Proper treatment administered quickly should cure all symptoms of DCS.

If you are diagnosed with decompression sickness, follow your doctor's instructions .