Diving medicine,
Traveler diseases


What is Decompression Sickness (DCS)?

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.

Decompression sickness is not as common as you might think. It is also very easily avoided.

What causes Decompression Sickness (DCS)?

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.

Relating to henry’s law, if the pressure increases (gets more) the more gas will be dissolved (go into) the liquid. if the pressure is decreased (gets less) the gas will come out of the liquid (the human body is mostly made of liquids). because the body does not use nitrogen, however when under pressure (diving) our body is exposed to a higher absorption rate of nitrogen (he body has to store this nitrogen within the body) on ascent when diving the pressure on the body is reduced (gets less) and the nitrogen in the body has a higher pressure and has to come out (supersaturation – like when opening a coca-cola bottle after shaking it) as long as the nitrogen comes out slowly and is controlled, there is no problem.

However, if the pressure is released too fast the nitrogen will come out too fast. this will cause bubbles, which causes decompression sickness!


Here are the main contributing factors to decompression sickness (DCS):

- 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.
These usually 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)!

Other factors that may predispose a diver to develop DCS :

- Fat: Fat releases nitrogen slowly. More nitrogen in solution after a dive.
- Age: As we age our circulatory system becomes less efficient.
- Dehydration: reduces blood in circulation, slowing nitrogen elimination.
- Injuries / illness: may alter or restrict circulation.
- Alcohol: before or after diving will alter circulation and causes dehydration.
- Carbon Dioxide Excess: from skip breathing.
- Cold Water: circulation to the extremities reduces as a diver cools, slowing nitrogen elimination from those areas.
- Heavy Exercise: before, during or after a dive accelerates circulation.
- Altitude / Flying: dive tables / computers are based on surfacing at sea level, thus exposure to lower pressure increases the tissue pressure gradient.

Types of decompression sickness(DCS)

image004- DCS Type 1– identified as ‘pain only’ DCS( limp and joint pain only )
Limb pain is the most common :may be mid-limb or joints
Cutaneous DCS (skin bends) :red rashes / patches usually on shoulders and upper chest.
- DCS Type 2 – identified as having life threateninginjuries(cardiovascular and neurological involvement)
Symptoms : involves brain nervous system, lungs, numbness and / or tingling, Paralysis
Weakness / fatigue / nausea (getting sick), Unconsciousness and death

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
  • - Fatigue
  • - Itchy skin or a blotchy skin rash
  • - Vertigo or dizziness
  • - Confusion and personality changes
  • - Amnesia
  • - Unconsciousness
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!

How to Prevent Decompression Sickness?

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.
image008- 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.
As serious as decompression sickness is, it can be prevented if you dive conservatively, avoid a seesaw dive patter,also called yoyo diving, 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?

First aid! Treat all DCS as serious – even pain only!
image0091. Give patient oxygen – preferably 100% which lowers alveolar nitrogen to accelerate elimination from tissues and raises blood Oxygen levels to assist tissues with blood flow reduced by bubble blockage.
2. Keep a breathing patient lying down on their left side, with head supported (recovery position) which helps keep airway clear if patient vomits.
3. Lying level ensures blood flow to brain.
4. Advise patient not to sit up or walk around, even during transport or feeling better.
5. Lay non-breathing patient on back for rescue breathing
6. Contact emergency medical care
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.
Recompression reduces bubbles in body to a smaller size and forces them back into solution – often alleviates symptoms immediately.
The sooner recompression begins, the more likely the patient will recover without permanent injury.
Patients sometimes don’t want to believe they are suffering from DCI and object to seeing a doctor. Strongly urge patients to allow medical examination by emergency medical care.
With best regards from “ Siam International Clinic, THAILAND
References :
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Gastroenteritis is an infection of the gut (intestines). It causes diarrhoea and may also cause you to be sick (vomit), and have tummy (abdominal) pain and other symptoms. In most cases the infection clears over several days but sometimes takes longer. The main risk is lack of fluid in the body (dehydration). The main treatment is to have lots to drink which aims to avoid dehydration. You should also eat as normally as possible. See a doctor if you suspect that you are dehydrating, or if you have any worrying symptoms such as those which are listed below.

What is gastroenteritis and what causes it?

Gastroenteritis is an infection of the gut (intestines). The severity can range from a mild tummy upset for a day or two with mild diarrhoea, to severe diarrhoea and being sick (vomiting) for several days or longer. Many germs (viruses, bacteria and other microbes) can cause gastroenteritis.
A virus is the most common cause of gastroenteritis. Viruses are easily spread from one person to another by close contact. This is often because of the virus being present on people's hands after they have been to the toilet. Surfaces or objects touched by the infected person can also allow transmission of the virus. The virus can also be passed on if the infected person prepares food.
image005Food poisoning from eating food infected with microbes causes some cases of gastroenteritis.
Many different types of microbes can cause food poisoning.
Poisons (toxins) produced by bacteria can also cause food poisoning. Another group of microbes called parasites can also be a cause. Water contaminated by bacteria or other microbes is another common cause, particularly in countries with poor sanitation.

What are the symptoms of gastroenteritis?

image007The main symptom is diarrhoea, often with being sick (vomiting) as well.
Diarrhoea means loose or watery stools (faeces), usually at least three times in 24 hours. Blood or mucus can appear in the stools with some infections.
Crampy pains in your tummy (abdomen) are common. Pains may ease for a while each time you pass some diarrhoea.
A high temperature (fever), headache and aching limbs sometimes occur.
If vomiting occurs, it often lasts only a day or so but sometimes longer. Diarrhoea often continues after the vomiting stops and commonly lasts for several days or more. Slightly loose stools may continue (persist) for a week or so further before a normal pattern returns. Sometimes the symptoms last longer.

Symptoms of lack of fluid in the body (dehydration)

Diarrhoea and vomiting may cause dehydration. Consult a doctor quickly if you suspect you are becoming dehydrated. Mild dehydration is common and is usually easily reversed by drinking lots of fluids. Severe dehydration can be fatal unless quickly treated because the organs of your body need a certain amount of fluid to function.

Symptoms of dehydration in adults include:

  • Tiredness.
  • Dizziness or light-headedness.
  • Headache.
  • Muscular cramps.
  • Sunken eyes.
  • Passing little urine.
  • A dry mouth and tongue.
  • Weakness.
  • Becoming irritable.

Symptoms of severe dehydration in adults include:

  • Weakness.
  • Confusion.
  • Rapid heart rate.
  • Coma.
  • Producing very little urine.

Severe dehydration is a medical emergency and immediate medical attention is needed.!

Dehydration in adults with gastroenteritis is more likely to occur in:

  • Elderly or frail people.
  • Pregnant women.
  • People with severe diarrhoea and vomiting. In particular, if you are not able to replace the fluid lost with enough drinks.

When should I seek medical advice?

Seek medical advice in any of the following situations, or if any other symptoms occur that you are concerned about:
  • If you suspect that you are becoming lacking in fluid in the body (dehydrated).
  • If you are being sick (vomiting) a lot and unable to keep fluids down.
  • If you have blood in your diarrhoea or vomit.
  • If you have severe tummy (abdominal) pain.
  • If you have severe symptoms, or if you feel that your condition is getting worse.
  • If you have a persisting high temperature (fever).
  • If your symptoms are not settling - for example, vomiting for more than 1-2 days, or diarrhoea that does not start to settle after 3-4 days.
  • Infections caught abroad.
  • If you are elderly or have an underlying health problem such as diabetes, epilepsy, inflammatory bowel disease, kidney disease.
  • If you have a weakened immune system because of, for example, chemotherapy treatment, long-term steroid treatment, HIV infection.
  • If you are pregnant.
With best regards from “ Siam International Clinic, THAILAND