THEMES

Nitrogen narcosis

Nitrogen narcosis

If you are considering scuba diving at great depths, it is important that you know thenitrogen narcosis, also known as "Martini effect“.

Nitrogen narcosis: what it is

It is a reversible effect ofalteration of the state of consciousness caused by the accumulation of nitrogen in the blood at high pressures. This effect occurs at great depths and can be completely reversed in minutes by ascending to shallower depths.

Therenitrogen narcosisit is a phenomenon that involves various inert gases present in the mixture contained in the cylinder that accompanies you underwater. L'nitrogen it is an inert gas, which means that it does not participate in the gaseous exchange of the alveoli. It represents 78% of the air we breathe and when it binds oxygen it gives life to dinitrogen oxide (N.2OR).

Have you never heard of nitrous oxide? I bet yes, that's what they call it in the movieslaughing gas!

Nitrogen narcosis: effects

Deep water thrill ornitrogen narcosis, occurs at great depths due to pressure.

As the external pressure increases, the partial pressure of the inert gases dissolved in the blood also increases.

With this increase in pressure, the possibilities that nitrogen can bind to oxygen formingdinitrogen oxidethey are really high.

Nitrous oxide (N.2O), also known as nitrogen dioxide, is used inmedicineas an analgesic and anesthetic. This is the compound responsible for thenitrogen narcosis.

Why did I tell you that other gases are involved in nitrogen narcosis? Because all gases (except helium and probably neon) have potential effectsnarcoticson humans, albeit to varying degrees. The narcotic effect is greater in gases that are more fat-soluble.

Theeffectsperceived are:

  • altered state of consciousness often described as "drunkenness"
  • Temporary decline or loss of mental faculties
  • Numbness
  • Temporary decline or loss of movement skills
  • Slowed movements
  • Difficulty in making usual reasoning or movements
  • Decline of mental functions
  • Lack of motor coordination
  • Alteration of sensory processes (bizarre perceptions)
  • Vertigo and visual and auditory disturbances (more rarely)

There nitrogen narcosis does not present effects long-term.

With increasing depth, the effects can amplify until they become really dangerous for your safety and that of your diving partner.

How to avoid nitrogen narcosis

In the forums we often read of the ability to develop a "some tolerance to nitrogen narcosis". In reality this is completely impossible! Experienced divers can learn to cope and manage some symptoms of nitrogen narcosis but cannot develop any tolerance.

Wikipedia also states that this phenomenon may depend on "depth training": this is false. Yes, it depends on the physiological conditions of departure but it is not possible to train to avoid this phenomenon which is completely out of the reach of our will. This tells you why some divers don't blame anynitrogen narcosiseven beyond 50 meters, while others feel the symptoms already at much lower altitudes.

Nitrogen narcosis: is it dangerous?

It's dangerous? It is reversible, just go up to shallower depths to see it disappear. Theriskit does not exist if the diver is aware of his symptoms and goes back up to stop the process. There nitrogen narcosis becomes dangerous when the diver:

  • is not aware of what is happening,
  • he overestimates himself
  • underestimates the alteration of the state of consciousness that is manifesting

Nitrogen narcosis: depth

Therenitrogen narcosisit affects any diver even if each of us manifests onesensitivitydifferent. Each dive is carried out under different physiological and environmental conditions, so it is impossible to set a limit within which thenitrogen narcosis.

This mechanism generally occurs when the pressure is higher than about 4 atmospheres, therefore over 30 meters. At these depths recreational diving is difficult and in any case it is preferred to use gas mixtures with a low nitrogen content.

In theory, the limit of use of classic compressed air is estimated at around 70 meters but already beyond 40 meters many experts recommend mixtures containing gases such as helium (trimix or heliox). Helium, as stated, does not have a narcotic effect.

Recognizing nitrogen narcosis

Recognize thenitrogen narcosishe can save your life ... but I'll tell you right away that, because of his effects that alter your own perception, it's not that easy. During diving you must always be vigilant and pay close attention to all signals sent by the body.

The first symptoms can be the decisive ones but they generally lead you to underestimate the danger. The reason? Therenitrogen narcosisit can be manifested with an initialanxiolytic effect, with a feeling of tranquility, relief and can lead you to believe that you are master of the environment. This is until everything takes on a more surreal connotation.

“Personally I am quite sensitive to nitrogen narcosis. I am both attracted and frightened by it ... The narcosis of great depths has a fundamental advantage over alcohol, it is not addictive. It is sufficient to go back to lower depths and the brain is instantly free; there are no ghosts left when you wake up from a hangover. Every time I read a report on a record dive I want to ask the sample how drunk he was. "
- Jacques Cousteau, in The Silent World.

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