Decompression Sickness, what you need to know about “The Bends”

There is one simple way to avoid DCS, DON’T GO DIVING, if you are Scuba Diving then it’s all about accepting the risk, managing the risk and using best safe diving practices to minimise the risk.

What is DCS and what causes it ?: – A simple explanation.

Air is basically 21% Oxygen and 79% Nitrogen, during diving the “partial pressure” of both the nitrogen and Oxygen we breath increases.
When we descend to depth Nitrogen is absorbed in the bloodstream and dissolves into our tissues. The rate of this buildup depends on how deep we go and how long we stay down for.
As we ascend the same Nitrogen leaves the tissues and forms tiny bubbles which are absorbed back into our blood.
If the Nitrogen is not reabsorbed into our blood, these tiny bubbles become large bubbles and can cause some serious damage to our bodies.  

The Bends

How do I know if I have DCS? – What to look for:

  • Joint or Limb pain
  • Skin Rash
  • Nausea
  • Chest Pain
  • Severe Itching
  • Dizziness
  • Skin swelling
  • Ears Ringing
  • Extreme exhaustion
  • Shortness of breath
  • Confusion
  • Coughing (particularly coughing up blood or frothy sputum).

Who is at risk from DCS?

Every diver, on every dive carries some risk, managing this risk is part of good scuba diving.

DCS events or “Hits” can be random events, you can do everything right on a dive and still get “Hit”.
Many risk factors, some still unknown, can influence the probability of a diver suffering from DCS.

There are however certain factors that increase your own personal risk of DCS.

  • Being Overweight –  the higher your percentage of body fat, the higher the risk of DCS.
  • Being ill before a dive.
  • Being tired before the dive.
  • Dehydration before the dive.
  • Alcohol before the dive (most likely in your body from the night before).
  • Over exertion during diving.
  • PFO ( patent foramen ovale)

How do I avoid DCS?

You can’t avoid the risk of DCS (unless you simply don’t dive) but you can do everything possible to minimise the chances of personally suffering from DCS.

  • Dive well within the limits of your dive tables.
  • Be aware of your depth at all times during a dive.
  • When diving with a computer ensure the computer is set up correctly for “Air” (if that is your gas) and make sure that you understand what the computer display is showing you.
  • Remember that a Dive Computer is a “tool” to assist you in safe diving.
    A Dive Computer will not “keep you safe” if you ignore other safe diving practises.
  • Surface Intervals are important, don’t rush them.
  • If you are going to get cold during a dive then shorten the dive time or make the limits on your computer “more conservative”
  • Do not overexert yourself underwater.
  • Ascend slowly from every dive, 30 ft (10 m) per minute is a safe ascent rate.
  • Safety Stops really do enhance your safety, 3 minutes is a minimum, not a limit.
  • Do not shoot to the surface after your Safety Stop, use another minute or so slowly ascending to the surface.
  • Know the rules for flying / ascending to altitude after diving. Follow the rules.
  • If you are not trained to go “Deep” then stay away.
    Did you know that divers who dive deeper than around  80 ft (24m) will add in extra safety stops to ensure a safe ascent?
    Divers who have the proper training for deeper dives know exactly how to mange DCS risks, one of the advantages of training!
  • If you can, take the course and become an Enriched Air Diver.
    Diving with Nitrox can enhance your safety and lower your risk of DCS.
  • Follow the “Flying after Diving” rules.

Treatment for DCS

Because DCs manifests itself with varying degrees of severity it is important to determine how serious the symptoms are.
Immediate treatment steps to be taken:

  • Breath 100% Oxygen (usually at the dive site or on the dive boat).
  • Drink Fluids to help with Dehydration.
  • Call DAN for advice – even if you are not a member, advice is free.
  • Seek specialist medical treatment as soon as possible.

Remember DCS symptoms can appear up to 24 hours after diving, also in mild cases breathing 100% Oxygen can make the symptoms go away, only to come back after a few hours.

Early medical diagnosis is crucial.

Severe cases of DCS are likely to be treated in a Hyperbaric facility “the Chamber” where, to put it very simply, you are put back under pressure to clear the bubbles and then slowly returned to ambient pressure. Many courses of this treatment may be required and full recovery can sometimes take many months.

Putting it in perspective

Recreational Diving, done with proper training and staying within recommended depth limits is “Hazardous” rather than “Dangerous”. DCS is actually quite rare, research from DAN shows between 3 and 4 cases per 10,000 divers, approx 1,000 cases per year.
In over 4,000 dives I have only ever seen a handful of divers suffering from DCS.

Basic advice for new divers

  • Follow your training and your dive plan.
  • Ensure that the operator you are diving with has 100% Oxygen available, just in case.
  • When diving in new areas, take the time to check on medical facilities and the nearest “Chamber”.
  • Make sure you have Dive Insurance, or at least check the coverage if relying on holiday/travel/credit card insurance.
  • Have the telephone number for the Dan emergency hotline available 1 919 684 9111 this is 24/7 365 days and you can talk to a specialist dive physician for free.

Further reading:

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