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What is Decompression Sickness

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Scuba diving is always packed with action and adventure and a new world to investigate.

However, being underwater and needing a compressed air tank to breathe comes with certain risks.  

One of the most significant risks that all scuba divers face is decompression sickness, a grave issue that can occur when proper decompression procedures are not followed.

Let’s discuss what is decompression sickness, why it happens, how to recognize its symptoms, and how to prevent it.  

What is Decompression Sickness? 

Decompression sickness is a condition that results from a sudden decrease in pressure that causes nitrogen bubbles to form in the bloodstream and body tissues.

These nitrogen bubbles can then cause severe problems, sometimes fatal.  

The scientific name for decompression sickness is generalized barotrauma and is colloquially known as the bends.

It results from a drastic and fast decrease in pressure, which can refer to the air or water around you, but of course, we are talking about water for scuba diving.  

Why Does Decompression Sickness Occur? 

As stated above, decompression sickness occurs due to a rapid decrease in the pressure surrounding you, but there is more to it than this.

When you scuba dive, you dive with compressed air, usually always oxygen and nitrogen.

When you dive, your body uses that oxygen to keep itself going, but the nitrogen stays in your blood.  

If there is a significant change in pressure when you ascend, the rapid pressure decrease causes bubbles to form and expand as you ascend.

Instead of letting the nitrogen escape naturally, these bubbles circulate in your bloodstream, traveling to joints and organs.  

If you ascend according to the dive tables, taking decompression stops along the ascent, you give your body time to breathe off the excess nitrogen and equalize according to the water pressure you’re at.  

A decompression air table can tell you exactly when, where, and for how long you need to make decompression stops along your ascent.  

Moreover, keep in mind that the duration of your dive affects this as well.

Even if you do not go all that deep, if you dive for too long and rapidly ascend, it may still cause decompression sickness.  

Decompression Sickness

Symptoms of Decompression Sickness 

Decompression sickness is not something that you will see or notice right away.

For example, only 10% of scuba divers experience decompression sickness symptoms within one hour after surfacing.

However, up to 90% of scuba divers show symptoms after six hours or more after the event. 

The first symptoms include fatigue, loss of appetite, a feeling of illness, and headache.

What is equally important to know is that there are two types of decompression sickness, type 1 and type 2.  

Type 1 is the less severe kind that usually just involves the musculoskeletal system.

The main symptom of type 1 decompression sickness is extreme muscle and joint pain, along with possible swelling of the arms, chest, and abdomen, skin mottling, rash, and itching.  

Type 2 decompression sickness is far more severe and also involves the brain; it features neurological symptoms.

These neurological symptoms may include headache, confusion, double vision, trouble speaking, loss of consciousness, tingling in the extremities, paralysis, possible irreversible paralysis, and death.  

There are also some cases where the inner ear is affected, which causes ringing, vertigo, and hearing loss.

In addition, in some situations, the lungs may be affected, where chest pain and trouble breathing are common, and sometimes even death.  

Is Decompression Sickness Fatal? 

In extreme cases, decompression sickness can be fatal.

However, with the current rate of one in every 77,000 people dying from the bends, the chances of it being fatal are very low.  

How to Treat Decompression Sickness 

For milder forms of decompression sickness, a doctor may prescribe 100% oxygen, providing relief from symptoms.

Other than that, the only thing to do is to wait it out.  

For severe cases, people suffering from decompression sickness will be put in a hyperbaric chamber (AKA a recompression chamber) to restore normal oxygen and blood circulation.  

How to Prevent Decompression Sickness  

The only real way to prevent decompression sickness when scuba diving is to limit the depth and duration of your dives to the point where decompression stops are not needed or to follow all necessary guidelines and procedures regarding decompression stops.  


Although not often the case, decompression sickness can be fatal, so you want to make sure when diving that you don’t exceed the recommended ascent rate and take the proper decompression stops along the way to the surface. 

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