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>The topic of "oxygen narcosis" has come up, and I thought I'd share an
Not to be confused with inert gas narcosis, but what is "oxygen narcosis".
Oxygen is metabolised and is not good for you at high partial pressures. I
don't see how it can induce narcosis. I think I'd rather call this
smoething other than oxygen narcosis.
>change to what I call "cold" narcosis. The symptoms (for me) included
>tingling in the extremities, strong paranoia, tunnel vission, etc.; but
Sounds like hypoxia
>I have NEVER experienced those "cold" narcosis symptoms at a depth that
>shallow while breathing air. I am now convinced that the "cold" narcosis
>is related in some way to oxygen.
>One explanation, therefore, is that the "cold" narcosis symptoms are not
>narcosis at all - but have something to do with oxygen toxicity. However,
Good working hypothesis
>I have been much deeper than 275' on air many times, and although the
>"cold" narcosis symptoms increase in intensity with increase depths, I
>have never experienced any of the classic oxygen toxicity symptoms on any
>of these dives (e.g. twitching of facial muscles, etc.).
Becasue it's hypoxia, not hyperoxia?
>Another complication is that I've never experience "cold" narcosis when
>breathing pure oxygen at high partial pressures. I've breathed 100%
>oxygen at a simulated 60fsw in a chamber for many hours without any sign
>of "cold" narcosis. I've even breathed O2 at 220' in a chamber (as a
>result of a mistake), again with no "cold" narcosis symptoms.
We can still invoke hypoxia.
>Thus, it seems there is some sort of a synergistic effect with high PPO2's
>& PPN2's that causes intense (i.e., "cold") narcosis symptoms.
I'm thinking about it....
>Of course, there are other explanations for my "cold" narcosis other than
>actual "narcosis" (as it is with nitrogen) - things like constriction of
>perhipheral circulatory system, etc. But my main point is that nitrox is
What about constriction of blood vessels in the central nervous system? I
am thinking of how it could be hypoxia.
>Who knows? But it's interesting to think about. I'd love to get involved
>with controlled chamber experiments to probe the question more carefully.
What sort of model would you use? It would be ethically "difficult" to
expose people to a possibly harmful dose of whatever this phenonemon is.
Since ethanol potentiates inert gas narcosis you could easily test whether
"oxygen narcosis" has a similar mechanism to inert gas narcosis by downing a
few beers befor you dive.
For myself I'd like to avoid calling this phenonemon "oxygen narcosis". Can
you think of another name?
/Rat
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
shelps@ac*.ma*.ad*.ed*.au* Stephen Helps
FAX (08)232-3283 Anaesthesia & Intensive Care
Voice (08)224-5495 University of Adelaide
ADELAIDE, 5005, South Australia
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If there is a 50-50 chance that something can go wrong, then 9
times out of ten it will. (Paul Harvey News, 1979)
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