Alternative Names decompression illness, caisson disease, the bends
Definition Decompression sickness takes place when sudden pressure changes in the environment cause gases that are dissolved in the blood and tissues to form bubbles of gas. These bubbles then block the flow of blood and can produce pain and other symptoms, even death.
What is going on in the body? When a deep-sea or scuba diver moves from deep to shallow water, he or she moves from a high-pressure environment to a low-pressure environment. When people breathe air under high pressure (for example from a scuba tank while deep-sea diving), they take in increased amounts of gases from the compressed air. These gases dissolve in the blood and tissues and slowly build up. The only way some of these gases can leave the body is through the lungs. However, this process takes time. If a diver rises too quickly to the surface of the water, the pressure may not be high enough to keep the built-up gases dissolved. This can cause bubbles to form in the blood and tissues and decompression sickness to develop.
The gas bubbles that form can block blood flow and cause increased pressure inside tissues of the body. This results in pain and other symptoms. If left untreated, this condition can lead to organ damage and even death.
What are the signs and symptoms of the disease? Pain is the most common symptom of decompression sickness. This usually occurs in or near an arm or leg joint. The pain may be mild or severe and may steadily get worse in more serious cases. Other signs and symptoms may include:
What are the causes and risks of the disease? Decompression sickness can be seen in:
scuba divers who rise too quickly after diving in deep water
those who go quickly from a lower to a higher altitude
those who exit from a high pressure or hyperbaric chamber
For scuba divers, conditions which increase the risk for decompression sickness include:
dives deeper than 10 metres
multiple dives in a short period of time
flying on an airplane shortly after diving
What can be done to prevent the disease? The best way to prevent this condition is to limit the depth and duration of scuba dives. Short, shallow dives do not require what is called decompression. Decompression involves stopping and waiting for a period of time at different depths as one rises to the surface. This allows the extra dissolved gases that build up to escape through the lungs as the person breathes. This prevents too many gas bubbles from forming. Using proper decompression can prevent decompression sickness entirely after deeper or longer dives.
In addition, the time between dives should be more than 12 hours. A person should spend at least 24 hours at the surface before going to an increased altitude, which includes flying. Obese divers should attempt to lose weight.
How is the disease diagnosed? An experienced diver may recognise the signs and symptoms of this condition. Otherwise, a doctor can usually make the diagnosis after a history and physical examination.
What are the long-term effects of the disease? If treatment is given right away, there are often no long-term effects. Permanent bone damage, chronic pain, brain damage leading to paralysis or other problems, and even death may occur in untreated or severe cases.
What are the risks to others? Decompression sickness is not contagious and poses no risks to others.
What are the treatments for the disease? Treatment of decompression sickness involves recompression in a high-pressure chamber. This device gradually increases the pressure around the person, forcing the bubbles to dissolve again. The pressure is then slowly reduced, allowing time for the person to breathe out the extra gases. In more severe cases, medications called corticosteroids, such as prednisone, may be to reduce inflammation or brain swelling.
It may take time to get a person to a facility with a high-pressure chamber. In these cases, 100% oxygen should be given with a close-fitting mask. The person should also be asked to drink large amounts of fluids.
What are the side effects of the treatments? The high-pressure chamber has few side effects when used correctly. Decompression that is too rapid can cause a return of symptoms. Corticosteroids can cause mood swings, high blood pressure, and high blood sugar levels.
What happens after treatment for the disease? After proper treatment, decompression sickness goes away. However, permanent damage may occur when treatment is delayed or after repeated or severe episodes. These complications may need further treatment.
How is the disease monitored? After treatment, no further monitoring is needed unless permanent body damage occurs.
Author: Reviewer: HealthAnswers Australia Medical Review Panel Editor: Dr David Taylor, Chief Medical Officer HealthAnswers Australia Last Updated: 1/10/2001 Contributors Potential conflict of interest information for reviewers available on request
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