Narcosis Properties of Different Gases

[gianaameri]

I don't think 'proof' works quite like that.

Is the fact that Bennett in Physiology and Medicine of Diving (Fifth Edition) makes no mention of "O2 Narcosis" proof that he was high on O2 at the 1970 Proceedings of the Fourth International Congress on Hyperbaric Medicine?

Is the fact that Edmonds in "Diving and Subaquatic Medicine" (Fourth Edition) makes no mention of "O2 Narcosis" proof that Bennet was not high on O2 when he wrote "Physiology and Medicine of Diving" ?

 

[nimoh]

I don't think 'proof' works quite like that.

It does prove that O2 is narcotic, just not as narcotic as N at lower partial pressures. When discussing "recreational diving" we can assume the depth is 130' or less. 100' END's are common due to the fact that we don't really start seeing narcosis until we hit this depth without some other underlying cause such as CO2 retention for example.

All this is to state that the narcotic difference between 21% and 32% is damn near a wash because the narcosis that a diver likely encounters will be a combination of all three gases. DAN agrees with this and so do a few other reporting agencies.

If there's a counter argument I'd just like to see some actual research to dispute it. Currently the consensus is that the use of Nitrox is to extend NDL dives and accelerate decompression schedules not to reduce narcosis.

I think my sarcasm may have flown under the radar...or rather, floated under the sonar.

 

[PfcAJ]

Yea, I missed the sarcasm. I see it now. My bad.

"No mention" of something is not proof. Learn 2 science.

 

[gianaameri]

Yea, I missed the sarcasm. I see it now. My bad.

"No mention" of something is not proof. Learn 2 science.

No proof of something is no proof.

 

[PfcAJ]

Everyone is wrong except you. Ok. We get it.

So brave with your 1 man army.

 

[syntaxerrorsix]

Is the fact that Bennett in Physiology and Medicine of Diving (Fifth Edition) makes no mention of "O2 Narcosis" proof that he was high on O2 at the 1970 Proceedings of the Fourth International Congress on Hyperbaric Medicine?

Is the fact that Edmonds in "Diving and Subaquatic Medicine" (Fourth Edition) makes no mention of "O2 Narcosis" proof that Bennet was not high on O2 when he wrote "Physiology and Medicine of Diving" ?

The goal for you at this point is to prove your statement that Nitrox reduces narcosis.

I've provided reputable research that disagrees with your theory. If you can't provide a counter-argument based on similar research we can just move on.

 

[ScubaSteve]

......we can just move on.

<snicker> Good one!

 

[Dr. Lecter]

It does prove that O2 is narcotic, just not as narcotic as N at lower partial pressures.

Small quibble: the research cited earlier showed that O2 was almost four times more narcotic than N, in that it would produce the same level of impairment at only a fraction of the PP.

What's really interesting is that the level of impairment produced by O2 at 1.65ATA or N2 at 6.3ATA was only 10%. For either gas, that's about the same as doing an air dive to 230'. I'm familiar with narcosis like that, and while I find it workable under the right conditions, it doesn't feel like just a 10% impairment...and I think most others who have experienced that kind of narcosis would agree. Assuming a linear scale (admittedly, I have no reason to do so), you'd have almost 75% of the impairment of a 230' air dive on EAN30 at 100' (1.2pO2), versus about 50% of that level of impairment doing the same dive on air.

One begins to wonder if the problem with proving narcotic properties of any of these gasses at recreational depths is one of scientifically detectable effects...determining a 5% or 3% level of impairment relative to background may be impossible, while determining something like a 10% level may be all we can reliably distinguish from 'normal.'

 

[syntaxerrorsix]

Small quibble: the research cited earlier showed that O2 was almost four times more narcotic than N, in that it would produce the same level of impairment at only a fraction of the PP.

What's really interesting is that the level of impairment produced by O2 at 1.65ATA or N2 at 6.3ATA was only 10%. For either gas, that's about the same as doing an air dive to 230'. I'm familiar with narcosis like that, and while I find it workable under the right conditions, it doesn't feel like just a 10% impairment...and I think most others who have experienced that kind of narcosis would agree. Assuming a linear scale (admittedly, I have no reason to do so), you'd have almost 75% of the impairment of a 230' air dive on EAN30 at 100' (1.2pO2), versus about 50% of that level of impairment doing the same dive on air.

One begins to wonder if the problem with proving narcotic properties of any of these gasses at recreational depths is one of scientifically detectable effects.

This is why I believe CO2 retention has more to do with perceived narcosis more than N or O2 at these depths. If you aren't physically exerting yourself, skip breathing what have you it's very unlikely that you experience any narcosis. That's also a reasonable explanation for the common 100' END. We just don't see any narcosis until we get past that point on average.



Boy I hope no one noticed the "excreting yourself" typo before I fixed it...

 

[PfcAJ]

One begins to wonder if the problem with proving narcotic properties of any of these gasses at recreational depths is one of scientifically detectable effects...determining a 5% or 3% level of impairment relative to background may be impossible, while determining something like a 10% level may be all we can reliably distinguish from 'normal.'

Bingo. Its difficult to reliably measure small differences because there is so much intra and inter subject variation. This is why experiments around narcosis involve high pressures. Makes it easier to test.

This is not uncommon in psychological experiments.