What is decompression sickness?
When we breathe underwater, approximately 79 percent of the air (depending on the gas blend) we’re breathing is nitrogen. As we descend deeper, the pressure around our bodies increases, causing our body tissue to absorb nitrogen.
Doctors use the term decompression sickness, or “the bends” to describe the illness and effects that result from a reduction in the ambient pressure surrounding the human body.
As long as the diver remains at pressure, the gas presents no problem. If the pressure is reduced too quickly, however, the nitrogen comes out of solution and forms bubbles in the tissues and bloodstream. This commonly occurs as a result of violating or approaching too closely the dive-table limits, but it can also occur even when accepted guidelines have been followed. (Like in the video above)
Bubbles forming in or near joints are the presumed cause of the joint pain of a classical “bend.” When high levels of bubbles occur, complex reactions can take place in the body, usually in the spinal cord or brain. Numbness, paralysis and disorders of higher cerebral function may result. If great amounts of decompression are missed and large numbers of bubbles enter the venous bloodstream, congestive symptoms in the lung and circulatory shock can then occur.
Doctors diagnose DCS on the basis of signs and/or symptoms after a dive or altitude exposure.
Two Types of DCS
Type 1: Type 1 DCS is the least serious form of DCS. It usually involves pain in the body and is usually not life threatening. It is important to understand that type 1 DCS can be part of the warning signs for type 2 DCS.
- Cutaneous Decompression Sickness
This occurs when nitrogen bubbles come out of solution in skin capillaries, resulting in a rash, often near the chest and shoulders.
- Joint and Limb Pain Decompression Sickness
Aching and/or pain in the joints characterize type 1 DCS. The pain can be in one place or it can move around the joint.
Type 2: Type 2 DSC is more serious and can be life threatening, usually affecting the nervous system.
- Neurological Decompression Sickness
When nitrogen bubbles affect the nervous system they can cause problems throughout the body. This type of decompression sickness normally shows as tingling, numbness, respiratory problems and unconsciousness. Symptoms can spread quickly and, if left untreated, can lead to paralysis or even death.
- Pulmonary Decompression Sickness
This is a rare form of decompression sickness that occurs when bubbles form in lung capillaries. Fortunately, the bubbles dissolve naturally through the lungs most of the time. However, it is possible for them to interrupt blood flow to the lungs which can lead to serious and life-threatening respiratory and heart problems.
- Cerebral Decompression Sickness
It is possible for bubbles that make their way into the arterial blood stream, move to the brain, and cause an arterial gas embolism. This is extremely dangerous and can be identified by symptoms such as blurred vision, headaches, confusion and unconsciousness.
Symptoms of DCS
- Extreme fatigue
- Joint and limb pain
- Red rash on skin
- Respiratory problems
- Heart problems
- Blurred vision
- Ringing of the ears
- Stomach sickness
Signs of DCS
- Skin may show a blotchy rash
- Paralysis, muscle weakness
- Difficulty urinating
- Confusion, personality changes, bizarre behavior
- Amnesia, tremors
- Coughing up bloody, frothy sputum
- Collapse or unconsciousness
**Symptoms and signs usually appear within 15 minutes to 12 hours after surfacing. In severe cases, symptoms may appear before surfacing or immediately afterwards. Delayed occurrence of symptoms is rare, but it does occur, especially if air travel follows diving.
Preventing Decompression Sickness
You can help minimize the risk of DSC by using a dive planner or a dive computer properly. You also need to follow other dive-safety practices that you should have learned in your scuba training.
Factors to consider when diving
- Never dive to the limits. Always have a margin before you hit your dive/table limit.
- Fat: Nitrogen dissolves easily into fat tissue. People with a larger ration of fat to body weight may absorb more nitrogen when diving.
- Age: As you get older, your circulatory system becomes less efficient, affecting nitrogen elimination.
- Alcohol: Any type of alcohol before or right after a dive can accelerate and alert your circulation.
- Cold Water: Diving in cold water can cause your extremities to receive less circulation as they cool, which effects nitrogen elimination.
- Hot shower/bath: Hot showers and baths after a dive cause capillaries to dilate, which will draw blood away from other areas. These areas will then eliminate nitrogen more slowly.