Decompression sickness (DCS) also known as "the bends" is one of the few bad things that can happen to us as divers.
It might occur when you surface from a dive too fast, and the excess nitrogen in your body that has built up during the dive as a side effect of breathing air at a higher ambient pressure does not have time to be released from your body, but instead forms bubbles that will travel through your system, until they find a nice spot to nestle.
While definitely something to take into consideration, decompression sickness is not as common as you might think. It is also very easily avoided, as you might remember from your Open Water Diving course, in case you already are a certified diver.
What causes Decompression Sickness?
During your open water course, you have looked at the primary cause for getting bent, which would be a rapid ascent, but there are many contributing factors that will make decompression sickness more likely. Some of these you have to take into consideration during the dive.
Prevent seesaw diving patterns, also called yoyo diving, strenuous activity or stress during the dive, reaching your physical limits (think fighting a current, working, object recovery for when you finally found that treasure chest) or very deep dives and staying at depth for an extended period.
But also on land and before and after the dive, you can contribute to not getting decompression sickness by following the rules below.
- Dive well rested (especially if you are planning on doing one of those BIG dives on your bucket list!).
- Give yourself plenty of surface time in between dives to get rid of extra nitrogen.
- Maintain a reasonable level of fitness for the sort of diving you want to do, get a medical check-up regularly and stay hydrated.
Here are the main contributing factors to decompression sickness in a nutshell:
- Diving in cold water
- Taking part in strenuous exercise at depth
- Deep diving for an extended amount of time
Although decompression sickness is dangerous, it is very rare, with around 1,000 divers a year in the US experiencing it in one form or another.
I have been working as a scuba instructor for many years and experienced very few cases of decompression sickness (I recall three in total. These three all occurred after multiple dives on multiple days and linked to inadequate hydration and a “bad” diving profile with a rapid ascent and / or no safety stop).
Also read: Why You Should Never Miss A Safety Stop?
Since off-gassing is not an “exact science”, there is no way of telling if and when a diver will be affected. One day you come up a bit quick after a 30 m dive and you are fine, the next day, maybe not so, and you might experience one or more of the symptoms of decompression sickness.
The Symptoms of Decompression Sickness
If you or a fellow diver believes they are suffering from DCS, there are a few signs and symptoms that you should look out for.
- Pain in the joints
- Tingling, numbness or paralysis
- Itchy skin or a blotchy skin rash
- Vertigo or dizziness
- Confusion and personality changes
These symptoms can appear within 15 minutes of surfacing from the dive, however in some cases, they can take up to 24 hours to appear. In very rare situations symptoms can show after 24 hours although this almost always happens after a period of air travel. You should also remember and respect the rules regarding diving and flying at all times.
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How to Prevent Decompression Sickness?
As serious as decompression sickness is, it can be prevented if you dive conservatively, avoid a seesaw dive pattern, dive well within your physical limits and make sure to take a safety stop at 5 meters for the required amount of time (usually three minutes).
If you are deep diving, you will need to take safety stops at various depths to ensure the nitrogen is removed from your body in the safest manner. You should also limit the amount of time that you spend at depth, especially in cold water and avoid strenuous activity.
To prevent a rapid ascent, you should make sure that you do not inflate your BCD, lose your weight belt or do anything else to increase the rate at which you travel up to the surface.
How Should You Treat Decompression Sickness?
All forms of decompression sickness, no matter how severe should be treated in a decompression chamber (hyperbaric chamber) not by re-descending and ascending again!
In-water recompression can make things worse and is never a good idea! Early oxygen first aid should also be administered and in some situations, this can reduce the symptoms of DCS substantially. If symptoms are reduced after oxygen administration, continue giving oxygen, since this confirms a decompression sickness!
After coming out of the water, the severity of the DCS should be determined where possible as this will determine the amount of oxygen needed and the urgency of getting them to a decompression chamber.
The closest decompression chamber should be notified as soon as possible. Depending on the severity of decompression sickness, divers will receive treatment and then be advised as to how long they have to stay out of the water – this will be at least two weeks.
There should be an oxygen kit with various masks and a trained oxygen provider on all dive boats, who will be able to help you in the unlikely event you might get decompression sickness. But nevertheless, you should check when speaking to the dive center for the first time.
Do you have any experience with decompression sicknes? Let us know in the comments below
Rutger Thole is an avid scuba diver and loves to travel, dive and write about scuba diving. Based in Amsterdam, he runs bookyourdive.com and at least twice a year he plans a dive trip off the beaten track.