Immersion and decompression sickness

Immersion and decompression sickness 

First things to do!!

Diving casualties need  oxygen immediately! preferably 100% via a mask with a so-called  reservoir. 

Well equipped diving centres or diving boats should always provide a sufficient number of these masks. After that, the casualty needs to be transported to a hyperbaric chamber as fast as possible. The commonly known wet recompression with normal air,  besides being an enormous risk for the dive partner, is often ineffective and is therefore not recommended by diving insurers such as DAN.

A complete list of all German emergency hyperbaric chambers which are operating on 24 hour stand-by can be found on the website: 

You should also find out where the nearest hyperbaric chamber is to your dive site and its accessibility. The dive centre on site can often help with this.

Before the beginning of your holiday, check your insurance for cost coverage for treatment, transport (return flights etc) and logistics. Duplicate insurances could lead to longstanding disputes over whose jurisdiction it is. 

What is a diving accident?

The “diving accident" (also sometimes known as diver accident) is a collective term for all incidents which happen to the diver in the water or after the dive. Bear in mind that the causes of the dive accident will be directly related to the changed pressure conditions during diving or in the workplace.

This means other injuries such as cuts, bruises, stab wounds, broken bones as well as bites, poisoning etc caused by animals, should only be viewed as accidents which have occurred additionally to the diving accident. 

The "classic" diving accident is either  decompression sickness (also called Caisson disease), an overextension of the lungs or other injury i.e. sickness caused by differences in pressure. 

Explanation of Terminology:

Caisson Disease

250 years ago, French and Belgian engineers developed a system which enabled man to work on the bottom of lakes and rivers with “dry feet”. Basically these were wooden chambers (French: Caisson) of varying forms which were lowered to the ground.  The water was squeezed out using high air pressure. Through means of an airlock, workers were able to access the chambers, which stood under high pressure, to be able to work. Because the first “diving sickness” appeared in the Caissons (chambers),  it was named “Caisson disease". This term was taken over by the diving industry. In actual fact, decompression sickness is an injury and not an illness.

Under the heading Caisson Disease, here is a summary of all that can happen in the body due to nitrogen gas bubbles.

The main points:

  1. Diver fleas are nitrogen gas bubbles in the subcutaneous fat. It causes very severe itching and pain on/under the skin.
  2. Bends are nitrogen gas bubbles in the joints. Bends cause severe pain in the affected joints.
  3. Chokes are nitrogen gas bubbles in the pulmonary alveoli. This causes pain on breathing and may ultimately lead to acute respiratory distress.
  4. Severe form of bends are symptoms as described in no.2, but which occur during the dive itself.
  5. ZNS Symptoms are nitrogen gas bubbles in the nerves and in the brain. The diver can experience deficits in the nervous system such as paralysis, numbness, sensory irritation, visual disturbances, auditory dysfunction etc.
  6. Arterial gas embolism occurs when gas bubbles (nitrogen or other) pass through a hole in the septum into the vascular circulatory system. These gas bubbles can embolize and block the arteries. The underlying tissue dies.
  7. Barotrauma ( Baro = pressure, Trauma = injury ) This includes all injuries which occur under variations in pressure and in the body’s rigid cavities.

Differentiations can be made between over-pressure barotrauma und under-pressure barotrauma. So called barotrauma can occur in the following hollow body organs:

Lungs, outer ear, middle ear, upper and lower jaw, frontal sinuses, teeth, and in certain circumstances in the skin or eyes and in various smaller sinuses.

Important: All forms of Caisson disease, also Decompression sickness (DCS) need to be treated by a dive physician as well as in the hyperbaric chamber. The very nature of these injuries means they will worsen over many hours. If left untreated, Caisson disease causes longterm irreparable damage. 

Depth intoxication

Most of the rumours in the diving industry are about depth intoxication. Actually, depth intoxication is a type of nitrogen narcosis causing different symptoms at different depths which can be compared to alcohol intoxication.


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