(Caisson Disease; Altitude Sickness; Dysbarism; The Bends; DCS)En Español (Spanish Version)
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
- 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
- Visual disturbances
- Chest pain and severe coughing (rarely)
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.
Progressive Joint Damage
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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.
Decompression sickness may be prevented by:
- Limiting the depth and duration of deep sea dives
- Following standard diving guidelines
- Avoiding diving if you are obese, pregnant, have heart or lung problems, or have had a recent joint or limb injury
- Avoiding excessive alcohol consumption within 24 hours before diving
- Avoiding flying within 24 hours after deep sea diving
- Avoiding repeated dives within a 12-hour period
- Avoiding flights in nonpressurized aircraft
American College of Hyperbaric Medicine
Divers Alert Network
Undersea and Hyperbaric Medical Society
Berkow R, Beers MH, Fletcher AJ, eds. The Merck Manual of Medical Information—Home Edition . 2nd ed. Simon and Schuster, Inc; 2003.
Decompression sickness. DynaMed website. Available at: http://dynamed101.ebscohost.com/Detail.aspx?id=115933 . Accessed on November 10,2007
Goldman L. Cecil Textbook of Medicine . 22nd ed. Philadelphia, PA: Saunders; 2004.
Office of Aerospace Medicine. Federal Aviation Administration website. Available at: http://www.faa.gov/about/office_org/headquarters_offices/avs/offices/aam/ .
Last reviewed November 2007 by Marcin Chwistek, MD
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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