Narcosis Properties of Different Gases

[PfcAJ]

So much BS I don't know if I should offer toilet paper or a breath mint.

 

[Jim-SAR]

Food for thought...

O2 "IS" narcotic at recreational depths! There, I said it.











Given that the percentage of O2 is high enough.


That's why you have an MOD of 20 feet with 100% O2. ;-)



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[Kevrumbo]

"The Meyer-Overton hypothesis states that narcosis happens when the gas penetrates the lipids of the brain's nerve cells. Here it apparently interferes with the transmission of signals from one nerve cell to another. Exposure to nitrogen-oxygen mixture at high pressure induces narcosis, which can be considered as a first step toward general anesthesia. . . and narcotic potencies of inert gases are attributed to their lipid solubility." (see PADI Encyclopedia of Recreational Diving Ch.5/p22)

Of interesting empirical note,

from Wienke BUBBLE MODELS AND DECOMPRESSION COMPUTATIONS:
A REVIEW p.34:

To track gas transfer across bubble boundaries, we need mass transport coefficients . . . Table 4 lists [mass transport coefficients] for the same lipid-aqueous surfaces, using Eisenberg [28], Frenkel [33], and Bennett and Elliot [10]

Table 4. RGBM Mass Transfer Coefficients. . .

Gas (μm2/sec fsw)
Ne 10.1 × 10−6
He 18.4 × 10−6
Ar 40.7 × 10−6
O2 41.3 × 10−6
N2 56.9 × 10−6
H2 72.5 × 10−6

Notice that helium has a low mass transport coefficient, some 3 times smaller than nitrogen. . . [Qualitatively, this implies that Helium is less narcotic than Nitrogen].

Also:
Deep Air with increased Gas Density & Work-of-Breathing; then throw in Physical Exertion or a Stress Condition, resulting in overbreathing the regulator --all leading to the Vicious Cycle of CO2 Retention and sudden Narcosis. Can result in severe cognitive impairment at depth or worst case stupor and ultimately unconsciousness. . .

Taken from Undersea Biomedical Research, Vol 5, No. 4 December 1978 Hesser, Fagraeus, and Adolfson:
"Studies on the narcotic action of various gases have shown that the ratio of narcotic or anesthetic potency of CO2 and N20 approximates 4:1, and that of N2O and N2 30:1. From these figures it can be calculated that CO2 has at least 120 times the narcotic potency of nitrogen. Our data would suggest that the narcotic potency of CO2 is even greater, i.e., several hundred times as great as that of nitrogen."

 

[Dr. Lecter]

That's why you have an MOD of 20 feet with 100% O2. ;-)

Hey, according to the study regarding 1.65ATA O2 or 6.3ATA N2 equating to a 10% impairment...a lot of us are apparently narced out of our gords during gas switch stops.

 

[lanta]

Good lord. Is it over? It seems that he was unable to extricate himself.

He insisted on proof when he would have been better served by common sense. I gather neither camp can offer absolute proof of whether O2 has a narcotic effect at recreational depths but how likely is it that the demonstrated narcotic effect at deeper depths would ever drop off to ZERO as you rise in the water column? Surely it would lessen as the ppO2 lessened. Since we don't know (or can't know, or will never know because it's not worth knowing), the only prudent stand to take at this point is that O2's narcotic effect is diminished or overshadowed by other factors.

How unreasonable to take a counter intuitive stance and attempt to put the onus on others to prove it ain't so. The male ego in all its gory glory!!

 

[dfx]

Let's see...

Because the research cited by syntaxerrorsix shows that for O2 to be narcotic it requires 1.65 pPO2 (and this at depths greater than recreational diving depths)

No, it doesn't say that.

then I can make the assetion that O2 is NOT narcotic at a significantly lower pPO2 and depth (this also considering that science has been unable to show that O2 is narcotic at recreational diving depths).

You could, if your original premise were correct. But it's not, so you can't.

 

[kotik]

Let's see...


No, it doesn't say that.


You could, if your original premise were correct. But it's not, so you can't.

Please, I beg you let this go. A certain poster has resolved to stop posting, I encourage everyone to not try to bring them out of remission.

 

[dfx]

Please, I beg you let this go. A certain poster has resolved to stop posting, I encourage everyone to not try to bring them out of remission.

Hey, I'm enjoying this :tongue:

 

[Tigerman]

Hey, I'm enjoying this :tongue:

I did too for the first 50 posts, then my brain started getting numb and now I think I have developed a bad case of amnesia - which must mean o2 is not narcotic..

 

[kotik]

I was just happy to see this travesty stripped out of the accident thread to some degree--