Why Are Divers at Risk for Decompression Sickness?


Tales of “the bends” are often the first horror stories many divers hear before they first enter into the world of SCUBA. While the stories are justified, the condition can have severe and lasting implications on the body. It’s important to know that if you dive safely, you can avoid it entirely.

What are “The Bends” and How Do You Get Them ?

Decompression sickness (DCS), known as “the bends,” is a rare condition ( 3 or 4 cases per 10,000 dives) that happens when there is too much nitrogen in the diver’s body and too little time to get rid of it.

While underwater, your body absorbs nitrogen from breathing compressed gas. If you speed to the surface too quickly, your body can’t adjust and “off gas” or dissolve the nitrogen. The result is nitrogen bubbles in your tissues, which causes DCS.

Even on the safest of dives, you will have a residual amount of nitrogen in your body and can get DCS from diving too much. With each dive, more nitrogen is left over.

Decompression sickness is part of a larger term called decompression illness (DCI), which also includes Arterial Gas Embolism (AGE). An embolism occurs when nitrogen bubbles enter the lung circulation and go into the arteries, blocking blood flow. This happens when divers hold their breath on ascent to the surface.

Why is DCS Called “The Bends?”

The condition was first identified during the construction of the Brooklyn Bridge in 1878. DCS was originally called “Casisson Disease,” named after the large chambers workers used to stay dry underwater while building bridges and tunnels — “caisson” is French for “big box,” which is what the underwater chambers were called. When workers ascended to the surface after being underwater for hours in the chambers, many experiencd DCS symptoms. The reason decompression sickness is called “the bends” is because when nitrogen bubbles start to form near or inside joints, it causes pain. Sufferers doubled over, or leaned forward due to the pain. Their posture mimicked a popular women’s fashion of the time called the “Grecian Bend.”

French physiologist Paul Bert was the first to realize that breathing under pressure increased the amount of nitrogen in the blood. Workers did not do “safety stops” to allow the nitrogen to dissolve. Workers found that if they descended again, they tended to feel better.  After Bert’s discovery and recommendation to ascend slowly, fewer workers were affected, although many still were. Recompression chambers, chambers that mimicked the underwater pressure (known today as hyperbaric chambers) were built and installed at construction sites to treat workers beginning in 1879.

Later in 1907, English physiologist Dr. J.S. Haldane was conducting experiments with the Royal Navy. He discovered that instead of ascending slowly but continually as recommended by Bert, ascending in gradual stages prohibited nitrogen bubbles from forming in body tissue — hence, the “safety stop.” Using what he learned, Haldane created the first set of dive tables.

What are the Symptoms of Decompression Sickness?

Symptoms usually begin within 15 minutes to 12 hours after surfacing. Some common DCS signs and symptoms are:

  • Joint pain and numbness / tingling
  • Difficulty urinating
  • Muscle weakness
  • Unusual fatigue
  • Blotchy skin
  • Dizziness
  • Confusion
  • Unconsciousness

Some signs of an Arterial Gas Embolism can be similar to the “bends,” but also can include:

  • Blurred vision
  • Bleeding Froth from the mouth or nose
  • Chest pain
  • Not breathing
  • Death

Click to read a more comprehensive explanation of the different types and severity of decompression sickness.

Can Decompression Sickness Be Treated?

technician next to a hyperbaric chamber with a patientDCI manifests in varying degrees of severity. The first step is to determine how serious the symptoms are, and if life-threatening, immediately begin CPR and administer oxygen if possible. Arrange to have the diver evacuated. Call the Divers Alert Network (DAN) to find out where the nearest hyperbaric chamber is located. DAN experts can also provide advice on what to do next.

For less severe cases of decompression sickness, fluids and 100% oxygen should be administered as soon as possible in a medical facility.

In some cases, even after treatment, there may be residual effects. Depending on the severity, these symptoms may last a few hours or they may require additional treatment.

The good news is that most victims of DCS and DCI can find relief of symptoms.

How Can I Avoid Getting DCS or DCI?

  1. Plan your dive and pay attention to your depth — the risks increase the deeper you dive.
  2. No alcohol or recreational drugs before diving — they can cause dehydration and increased heart rate and can also interfere with rational thinking.
  3. Drink plenty of fluids but avoid caffeine – dehydration is one of the biggest risks for developing decompression illness.
  4. Ascend slowly and make more than one safety stop when diving deep.
  5. Exhale on ascent and never hold your breath.
  6. Make sure your surface interval times are sufficient between dives, and especially before flying or going to a high elevation.
  7. Avoid doing more than a few dives per day.
  8. Save DAN’s number into your dive log- 1-919-684-9111 to have just in case.
  9. If you’re haven’t already, consider taking a course to learn to how to become an Enriched Air Diver, often called Nitrox.
  10. If you are overweight or obese, your risks are higher because nitrogen absorbs more easily into fatty tissue.

If you’re in the Dallas metro area, we here at Scuba Toys offer a Nitrox course – learn more about breathing oxygen enriched air while diving.

Stop by our shop in Carrollton, TX, call us at 877-728-2243 or visit us at ScubaToys.com!

Have you ever experienced (or witnessed others) decompression sickness? Let us know in the comments section below!

Image Attribution: https://www.flickr.com/photos/chadlathe/

Article Name
Why Are Divers at Risk for Decompression Sickness?
Decompression sickness can affect any diver, even experienced ones who don't take risks. Read on to learn more about "the bends" and how to avoid it.

3 responses to “Why Are Divers at Risk for Decompression Sickness?”

  1. S.W. says:

    I’ve been diving for 13 years and have never experienced or witnessed decompression sickness firsthand.

  2. Vic says:

    No, I haven’t. But, it seems that the odds of experiencing it are low, especially if you follow the tips suggested here/the materials in your OW course.

  3. Solomon Adams says:

    20 years as an instructor and I’ve seen it all. It’s important to remember that DS can be avoided though.

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