One of the biggest risks of Scuba diving is Decompression Sickness (DCS), sometimes called ‘the Bends’, ‘Divers Disease’ or ‘Caisson Disease’. Knowing the facts and understanding all there is about decompression sickness is important for any person interested in the sport. While the basic decompression theory is covered in what you learn in an Open Water Diver certification course, we’re going to cover decompression sickness and its relation to scuba diving in detail right here.
What is Decompression Sickness?
Decompression sickness or ‘the bends’ is directly related to the Scuba Gas Laws- Henry’s Law in particular, which states that under pressure, a greater quantity of gas can be absorbed by a liquid. In a Scuba diver’s case this gas is the nitrogen that a diver breathes from the air filled in a scuba tank and the liquid absorbing it is his/her blood and body tissue.
Usually, nitrogen is expelled from a persons body during an exhale and through their skin. When breathing compressed air while diving, because of the ambient water pressure, the nitrogen is absorbed remains in the body’s fatty tissues and blood. The longer and deeper the dive, the more nitrogen is absorbed into the tissues. As long as the diver remains at pressure, the gas presents no problem. However, when the pressure around the diver decreases the nitrogen starts coming out of the tissues back into the blood stream. This is known as off gassing. If the pressure is reduced too quickly, the nitrogen starts forming bubbles in the tissues and bloodstream rather than being exhaled just like when you open a bottle or can of soda it releases the pressure causing the carbon dioxide gas to lose its solubility and escape in the form of bubbles or fizz.
The nitrogen bubbles that form in a persons body tissue can collect under the skin or within solid tissues inside the body causing severe pain as they collect near the joints. Bubbles that congregate within the joints are very painful and usually cause the person to bend over in pain which is why it’s called ‘the bends’. Sometimes however, the nitrogen bubbles can form in the bloodstream which restricts the flow of blood flow to the lungs causing sudden low blood pressure, slowing down of breathing and possibly shock. In extreme cases, nitrogen bubbles can form within the brain, spinal cord or nervous system column. This can result in paralysis and can even be fatal.
What Causes Decompression Sickness?
As we saw above, nitrogen bubbles start forming the body if pressure is reduced too quickly. When diving water pressure is reduces if a diver ascends too quickly. So, getting this nitrogen out of the tissues at the correct rate is a challenge divers face. When a diver ascends at the right rate and by stopping part of the way up, the pressure is released slowly and the gas diffuses from the tissues through micro-bubbles that can be exhaled safely. Another cause for decompression sickness is diving too long or too deep as more gas is absorbed into body tissue and in higher concentrations than normal.
Ascent to an altitude in the case of divers flying shortly after diving too can cause decompression illness as pressure in aircraft cabins is not actually maintained at sea-level pressure the change in pressure can cause bubbles to form in the body.
More about- Signs and Symptoms of Decompression Sickness, First Aid and Treatment for Decompression Sickness, Prevention and Avoiding Decompression Sickness in Decompression Sickness: All About Scuba Diving & The Bends (Part-2)
* Photo Credits: photos by ParaScubaSailor, chris5aw, ClifB on flickr
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