200' on air for 5 min bottom time?

[Ste Wart]

"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:


Quote:
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. . .

...and your point is what Kev?

He's a whizz at copy & paste by the looks of things. Lacking in point quoting articles nearly 20 years old though.

 

[Kevrumbo]

Don't feign dismissal what you don't understand Wart (or don't want to because of ignorance).

...and your point is what Kev?

The point is there is a quantitative metric showing a possible correlation between inert gas narcosis and a higher mass transport coefficient. (Tortuga68 --That's my opinion & my impression of the research articles "going back 20 years"...)

 

[Ste Wart]

Don't feign dismissal what you don't understand Wart (or don't want to because of ignorance).

The point is there is quantitative metric showing a possible correlation between inert gas narcosis and a higher mass transport coefficient. (Tortuga68 --That's my opinion & my impression)

I don't mind if you call me ignorant.

You might want check the difference between a hypothesis and a law when quoting though

 

[nimoh]

I am absolutely sure that the Meyer-Overton hypothesis might be true

 

[Tortuga68]

The point is there is a quantitative metric showing a possible correlation between inert gas narcosis and a higher mass transport coefficient. (Tortuga68 --That's my opinion & my impression of the research articles "going back 20 years"...)

You appear to be pointing out that He is less narcotic than O2 or N2

 

[Bombay High]

Wayne ... now I know why I was a diver and not a supervisor
Lot less to think about ... I just let you guys figure it out while I dive !

 

[DCBC]

Wayne ... now I know why I was a diver and not a supervisor
Lot less to think about ... I just let you guys figure it out while I dive !

LOL, Yes; it was a lot easier for me as well when all I had to do was dive. You make more money as you progress, but they actually expect you to work for it.

 

[Kevrumbo]

You appear to be pointing out that He is less narcotic than O2 or N2

As we have qualitatively known through our own experiences for years now. . .

 

[lamont]

Late to this party, but I'm calling b.s. on the "Adaptation" argument.

Around here we had a deep air diver (kirby) who had been diving that way for years. A long time ago he found the remains of a kid who had died doing a deep air bounce dive on a single -- while he was diving air on a single. After awhile he shifted to diving doubles but still diving solo deep air in the 180-200 foot range. If anyone was "adapted" it was him. He still very nearly killed himself by getting too narc'd on one of his deep air dives, when he came to he'd breathed his backgas down to nearly zero and wound up getting very bent, but managed to do enough decompression to avoid dying.

Water Taxi crew rescues scuba diver | Seattle 911 ? A Police and Crime Blog - seattlepi.com

As a practical matter you can yap all you want about narcosis adaptation, but I'm not buying it as being practical.

 

[Kevrumbo]

Late to this party, but I'm calling b.s. on the "Adaptation" argument.

Around here we had a deep air diver (kirby) who had been diving that way for years. A long time ago he found the remains of a kid who had died doing a deep air bounce dive on a single -- while he was diving air on a single. After awhile he shifted to diving doubles but still diving solo deep air in the 180-200 foot range. If anyone was "adapted" it was him. He still very nearly killed himself by getting too narc'd on one of his deep air dives, when he came to he'd breathed his backgas down to nearly zero and wound up getting very bent, but managed to do enough decompression to avoid dying.

Water Taxi crew rescues scuba diver | Seattle 911 ? A Police and Crime Blog - seattlepi.com

As a practical matter you can yap all you want about narcosis adaptation, but I'm not buying it as being practical.

Thank you for your subjective opinion and real life anecdote Lamont.

Recitation again of post#132, an objective study with practical caveats (and no bull stink):

"Moreover, our results suggest that experienced divers can discriminate between the behavioral and subjective components of narcosis. . .It has been proposed that the intensity of narcotic symptoms could be used by divers to gauge the extent of performance loss (10). The present results indicate that this advice is inappropriate for adapted divers because the two components of narcosis [behavioral and subjective] uncouple in a direction that could lead to an overestimation of performance capabilities --a potentially dangerous situation. On the other hand, the question arises as to whether adaptation confers any benefits on the diver, since performance efficiency is not directly improved and could be overestimated. In this regard, it could be argued that a reduction in symptom intensity reduces the possibility that attention will be focused on subjective sensations rather than the task at hand." [i.e. Subjective, sensations awareness vs. Situational, objective task-at-hand awareness??]
From:
p.9, Hamilton K, Laliberté MF, Fowler B. Dissociation of the behavioral and
subjective components of nitrogen narcosis and diver adaptation. Undersea Hyperb
Med. 1995 Mar;22(1):41-9. PubMed PMID: 7742709.