Nitrogen tolerance question

[jbd]

I heard that when diving with computers you can dive reverse profiles. On a show last night on OLN they were going do reverse profiles and the stated reason was to develope a tolerance to nitrogen so as to prevent nitrogen narcosis. Does a diver develope a tolerance to narcosis by using reverse profiles?

 

[Rick Murchison]

No.
Rick

 

[Campana]

no, they don't. It was believed by some divers in the past, even some diving greats, that they did develop a tolerance to Nitrogen and to Nitrogen Narcosis. Recent studies have shown that this is not true. Task performance deteriorates just as much in divers who believe that they have developed tolerance, though they believe themselves to not be narced, they are just as narced as ever. The belief that tolerance could be developed was a myth.

 

[dlarbale]

I'm not too sure about this non-tolerance to N2.

I can recall a 2 month period in Indonesia where I was diving fairly deep all the time. Now the thing that I remember most is the first couple of dives to depth and the almost instant slap in the face from N2. After a few deep dives the effects were definately less - no question.

So did I dream all of this or what? What evidence has been supplied to undermine the theory of the diving greats?

Dave.

PS// Are reverse profiles really so bad? I've read some interesting articles from the WKPP boys on this and it would appear that they even encourage it, see -

http://www.wkpp.org/articles/Decompression/repetitive_dives.htm

 

[hsantos]

... see below

 

[hsantos]

Building up tolerance for the N2 itself I have my own daughts, but i just learned in my TDI Advanced/Deco course that anxiety and stress can, and will, elevate you N2 Narcosis.

Is also related with the increased amount of the produced CO2.

Anxiety/Stress may be originated by severall factors such as: going behind your limits/qualification, cold, bad breathing habits, and task loading.

You can avoid anxiety by gaining experience in that kind of dives, and that experience will, for sure, lower your N2 narcosis...

So, one can say that you can build a "tolerance" for N2 by training !!

my 2 cents

Reverse profiles are more implicated in buble formation, but would be another (long ;-) ) discussion.

 

[The Chairman]

he is narced without needing to "feel" it. The dangerous diver thinks he is immune. While you may be able to better tolerate the "warm fuzzy" feeling, your judgement is STILL just as impaired. Thinking otherwise will kill you... just my two cents.

 

[Lost Yooper]

Here's just a couple reports that dismiss adaptation to narcosis:

http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?uid=2741255&form=6&db=m&Dopt=b

http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?uid=7742709&form=6&db=m&Dopt=b

I bet your TDI instructor never showed you such reports. Did he mention that CO2 is like 120 times more narcotic than nitrogen? What happens when things don't go quite right at depth and you start breathing heavily on a very dense gas like air? CO2 build up => a blast of narcosis. What are the odds of something going wrong on a deep air dive?

You're being brainwashed into believing you can adapt, deal with, or be reliably safe using air deep. You can't and anyone who is teaching otherwise is either clueless or is interested only in making money regardless of the welfare of their students, IMO. There is no middle ground in my mind. Cluelessness of individual students and instructors is fairly easy to understand since they're being fed this stuff from the top. However, those at the top are not clueless -- they just don't care (IMO of course).

Good luck,

Mike

 

[jetblast00]

dlarbale,
Next time your down deep for a few days in a row, bring a couple of math problems or some tavern puzzels with you and see if you can progressivly do different tasks of the same skill level quicker as you "build a tolerance". My money is on your times being the same... You may get more used to the narc and therefore not notice it as much, but it's still there and will still slow down your reaction times and desicion making abilities.

As for reverse profiles, I'd very much like to discuss them, let's start a new thread.

 

[Lost Yooper]

Based on all my readings on the subject of reverse profiles by people like Maiken, Younte, Baker, Hamilton, Jablonski, and Irvine, they are no more dangerous than forward profiles. In fact, somewhere I read that DCS is statistically less likely to occur with reverse profiles than forward profiles. Cripes, the last I heard, nobody even knows where or why reverse profiles became a bad thing. The navy and commercial guys used reverse profiles all the time without significant incident. I believe it had something to do with practicality of logistics or something for regular sport divers (something like that). It wasn't based on research as far as I know.

It is apparent that models like VPM and RGBM are better suited to deal with reverse profiles, however.

Mike

I think I still have a bunch of notes on the subject. I should take a look.