Narcosis Properties of Different Gases

[gianaameri]

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A ScubaBoard Staff Message...

This discussion on narcosis properties of different gases has been split from a thread in the Accidents and Incidents Forum. The original thread can be found here http://www.scubaboard.com/forums/ac...ed-his-brother-died-today-ginnie-springs.html
Marg, SB Senior Moderator

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It has been alleged that Carlos intended to dive to 30 meters/100 feet using Air and no one in a cave specific forum (CDG) seemed to think that as odd.

Air at 100 meters in a cave is inadvisable because of the risk of Narcosis.

I do not know how Carlos was trained to cave dive, but to me to seems odd that he would have planned a cave dive to 30 meters on Air.

He had N30 backmount.

 

[syntaxerrorsix]

Let us make it public here as the third relevant point to the Carlos incident.

It has been alleged that Carlos intended to dive to 30 meters/100 feet using Air and no one in a cave specific forum (CDG) seemed to think that as odd.

Air at 100 meters in a cave is inadvisable because of the risk of Narcosis.

I do not know how Carlos was trained to cave dive, but to me to seems odd that he would have planned a cave dive to 30 meters on Air.

He had N30 backmount, and whilst it would have been sensible for him to bring some O2 for deco, personally, I find it odd that he is alleged to have brought from Canada a bottle of Air for a 30 meter cave dive.

Lots of people dive air to 100'. I've dived air at Ginnie many times and I'm also trimix certified. Some people get narced in the bathtub.

Nowhere are you going to get 100 METERS at Ginnie.

You are just trying to troll a new board because of your failed ideas and nonsense on the last one.

 

[gianaameri]

Lots of people dive air to 100'.

I would dive Air to 40 meters happily, but on an Open Water recreational dive.

A cave dive is entirely another matter.

You need to have clarity of mind and past 21 meters on Air it starts going. At 30 meters you are narced silly.

Perfectly fine to be narced in a recreational dive, but entirely a different matter in a cave where you need to navigate, lay line, place jumps...

To stay on topic, was Carlos a cave diver who would dive Air 30 meters in a cave, or was he a cave diver who would understand 30 meters using Air in a cave is not such a good idea?

 

[syntaxerrorsix]

I would dive Air to 40 meters happily, but on an Open Water recreational dive.

A cave dive is entirely another matter.

You need to have clarity of mind and past 21 meters on Air it starts going. At 30 meters you are narced silly.

Perfectly fine to be narced in a recreational dive, but entirely a different matter in a cave where you need to navigate, lay line, place jumps...

To stay on topic, was Carlos a cave diver who would dive Air 30 meters in a cave, or was he a cave diver who would understand 30 meters using Air in a cave is not such a good idea?

Oh please. Just because you can't function at 100' doesn't mean others can't as well. If you honestly think the majority of people diving Ginnie are on mix you're daft.

The standard for most agencies is a 100' END.

 

[PfcAJ]

Let us make it public here as the third relevant point to the Carlos incident.

It has been alleged that Carlos intended to dive to 30 meters/100 feet using Air and no one in a cave specific forum (CDG) seemed to think that as odd.

Air at 100 meters in a cave is inadvisable because of the risk of Narcosis.

I do not know how Carlos was trained to cave dive, but to me to seems odd that he would have planned a cave dive to 30 meters on Air.

He had N30 backmount, and whilst it would have been sensible for him to bring some O2 for deco, personally, I find it odd that he is alleged to have brought from Canada a bottle of Air for a 30 meter cave dive.

[abstract] DOES OXYGEN CONTRIBUTE TO THE NARCOTIC ACTION OF HYPERBARIC AIR?
Roles of nitrogen, oxygen, and carbon dioxide in compressed-air narcosis

Air vs Ntrox doesn't matter. Oxygen is probably narcotic given Meyer-Overton and the available data, and if it is not directly responsible for the narcosis, the resultant co2 retention due to gas density is.

 

[gianaameri]

[abstract] DOES OXYGEN CONTRIBUTE TO THE NARCOTIC ACTION OF HYPERBARIC AIR?
Roles of nitrogen, oxygen, and carbon dioxide in compressed-air narcosis

Air vs Ntrox doesn't matter. Oxygen is probably narcotic given Meyer-Overton and the available data, and if it is not directly responsible for the narcosis, the resultant co2 retention due to gas density is.

There is no evidence that O2 is narcotic at recreational diving depths.

O2 in a chamber at 2.8 pPO2 produces no narcosis.

The study states "In this pilot study 3, 3 and 4 subjects were studied at 6, 8.5 and 11 bar respectively..."

I have yet to read the study, but it seems to me they are talking well above recreational diving depth.

Now, if O2 were narcotic at 100 feet/30 meters (no evidence of this exist that I know of), then arguably one could use Trimix for a 100 foot cave dive.

Personally, I find increasing O2 and decreasing N significantly reduces narcosis in the 24 to 30 meters range in cave diving.


---------- Post added August 26th, 2013 at 02:58 PM ----------

The standard for most agencies is a 100' END.

Is this for cave diving (and can you cite as an example which agencies adopt this standard)?

 

[lv2dive]

There is no evidence that O2 is narcotic at recreational diving depths.

O2 in a chamber at 2.8 pPO2 produces no narcosis.

The study states "In this pilot study 3, 3 and 4 subjects were studied at 6, 8.5 and 11 bar respectively..."

I have yet to read the study, but it seems to me they are talking well above recreational diving depth.

Now, if O2 were narcotic at 100 feet/30 meters (no evidence of this exist that I know of), then arguably one could use Trimix for a 100 foot cave dive.

Personally, I find increasing O2 and decreasing N significantly reduces narcosis in the 24 to 30 meters range in cave diving.

What I find odd is that Carlos allegedly carried from Canada an Alu80 bottle of Air (marked as O2...), when he also carried back-mount bottles of N30.

Air is cheap and it would have been easy enough for him if he wanted more gas to empty the Alu80 and fill it with the same gas he had in his back-mount (i.e. N30 which was quite suitable for the diving he intended to do).

Instead, he had an O2 bottle actually filled with O2 which we know he breathed at depth.

First of all you are making attributions about a study you acknowledge you haven't read... Rly?!?!?

Secondly, when nearly every major training agency* treats oxygen as narcotic, what are your credentials that we should go with your viewpoint over theirs?


*i don't know of any major training agency that does not treat oxygen as narcotic but admittedly have not been exposed to every major agency so I will leave it at "nearly"

 

[nimoh]

Is this for cave diving (and can you cite as an example which agencies adopt this standard)?

GUE for one.

Equipment Configuration | Global Underwater Explorers

 

[syntaxerrorsix]

Is this for cave diving (and can you cite as an example which agencies adopt this standard)?

I though I saw you were TDI Cave. TDI's Trimix course allows the diver to decide what the acceptable END is. Which portion of the TDI Full Cave book leads you to believe that isn't the case? Have you ever heard of their Extended Range course?

To answer your questions... YOUR training agency accepts DEEPER END's than 100' for all technical diving.

ETA...

NOAA considers O2 narcotic as well. Are you familiar with "Google"?

 

[PfcAJ]

There is no evidence that O2 is narcotic at recreational diving depths.

O2 in a chamber at 2.8 pPO2 produces no narcosis.

The study states "In this pilot study 3, 3 and 4 subjects were studied at 6, 8.5 and 11 bar respectively..."

I have yet to read the study, but it seems to me they are talking well above recreational diving depth.

Now, if O2 were narcotic at 100 feet/30 meters (no evidence of this exist that I know of), then arguably one could use Trimix for a 100 foot cave dive.

Personally, I find increasing O2 and decreasing N significantly reduces narcosis in the 24 to 30 meters range in cave diving.

What I find odd is that Carlos allegedly carried from Canada an Alu80 bottle of Air (marked as O2...), when he also carried back-mount bottles of N30.

Air is cheap and it would have been easy enough for him if he wanted more gas to empty the Alu80 and fill it with the same gas he had in his back-mount (i.e. N30 which was quite suitable for the diving he intended to do).

Instead, he had an O2 bottle actually filled with O2 which we know he breathed at depth.

---------- Post added August 26th, 2013 at 02:58 PM ----------



Is this for cave diving (and can you cite as an example which agencies adopt this standard)?

Your sample size of 1 diver and 'self assessment' doesn't help your credibility. Placebo affect could easily be at play here, and is a much more reasonable assumption (Occam's Razor) than trying to argue that Oxygen doesn't have narcotic potential when its been demonstrated to be narcotic (see above studies) and is predicted to be narcotic via Meyer Overton.

As far as research methods and experimental design go (something I know a little about), its not uncommon for researchers to produce 'unrealistic' situations in order to more easily study the affects of something. By using deeper depths, the test subjects are more likely to show outward and measurable signs of narcosis. Because of science, we can use this data to make informed assumptions about the behavior of subjects at less 'extreme' exposures. This is done as a matter of course across almost all fields of science. To state that o2 is not narcotic at 'recreational depths' is folly, as there is no evidence to support this claim. While impossible to "prove a negative", the positive has been clearly demonstrated. The 2nd linked study is even more in line with your criteria of 'recreational depths' and the researchers came to a similar conclusion as the 1st linked study.

Both GUE and UTD respect the 100' END limit, and other agencies are not far off. IIRC, most trimix classes stress the importance of maintaining a low END, and I think some even recommend the 100' limit. NOAA accepts the narcotic potential of nitrogen, and I believe DAN and the NEDU follow suit. Your 1 person self analysis doesn't really hold water.