Deep Air medical question(s)

[dc4bs]

Hi all,

I've been looking for info on "deep air" diving as I have a friend who want's to take the TDI deep air course (we took the deco course together in January).

I've been trying to talk him into just going right to the trimix course (what I plan to do). As I understand it, trimix is almost the same course as deep air but with the addition of helium.

That TDI seems to be the only agency teaching deep air, and only in the US now for some reason, just makes him want to do it more before they get around to droping it entirely.

Some of the reading I've done touches on things such as damage that can occur to the capilaries due to stiffening of red blood cells caused by high nitrogen PP among other problems. The posts/articles I've seen this type of info in didn't put refrences though. I have been unable to find published medical articles to back it up. Maybe I'm just not searching the right places?

If I can find some hard data on why deep air is not a good idea (aside from the narcosis issues), it will be much easier to get him to drop it and move on to trimix.

Personal opinions and anecdotal evidence will not cut it with this guy. I need hard-core medical info that I can point him to a library, medical journal or website (not www,some_guys_opinion,com either) so he can read it for himself. Come to think of it, I'd like to read up on it more too.

He's been quite deep on a few occations (I'll leave it at that) and because he got away with it those times... Well, you know where that goes.

 

[trymixdiver]

So if i cant say dont do deep air because of the N2 then how about because of the O2 pp at depth.

The partial pressure of the oxygen in air at 218 feet is 1.6 atmospheres absolute, which IS THE LIMIT. You can deco. at 1.6 a.t.a.'s, but that's at rest.

At 235 ft. oxygen PP is 1.622 a.t.a.'s and you're risking it all that you'll not have a seizure because of the high partial pressure of the 02. When we dive, we really need to keep that partial pressure of oxygen around1.4 and at 1.6 for the Deco portion. Doing your deco at a 1.6 is not the same as diving air at 235'. Your conducting your deco at rest ( at least you should be) and if your diving at 235' your not at rest, thats the working part of your dive. Heres 3 reasons why you shouldnt do deep air:

1. nacosis
2. O2 PP
3. Availability of trimix

There are alot of diviers who do / did deep air, that doesnt make it right.

Andy

 

[Friggincold]

The Physiology and Medicine of Diving..by Bennett & Elliot chapter 7 and 14 will explain RBCR.
Technical Diving in Depth by Bruce Wienke just published should give you some info to start with.
Hope this helps. Good Luck convincing him, it's in his best interest.
I am sure there are more references out there, I just don't have them here.
Friggincold:cold:

 

[Lost Yooper]

There are a few links that describe studies showing people cannot adapt to narcosis, which contradict what deep air agencies say. There's few links that describe how CO2 influences narcosis and toxicity. I think the CO2 issue is a biggie because breathing dense air at depth can lead to elevated CO2 levels. Compound that with stress and heavy breathing (unexpected problems), and you have a recipe for a potential disaster. As for red blood cells and capillary damage, I have heard that the Navy has some research on this, but I haven't seen it.

Let me know if you want the links to narcosis adaptation.

Mike

BTW, TDI isn't the only agency teaching deep air. NAUI, PADI, ANDI, and IANTD (in other countries) also have deep air programs.

 

[dc4bs]

Hi LY,

Yes, I'll take whatever links you have. The more ammo I can bring to the argument the better.

As for which agencies teach deep air, I hadn't really looked into it that much. I was told by my deco instructor that TDI was no longer offering it anywhere but the US. I just assumed that it was being phased out, but have no hard info on this. I suppose he could have been wrong as well.

My deco instructor also reccomended that we NOT take deep air but go straight to trimix. He is also a TDI deep air instructor but said that he will not teach it any more. The problem is that my friend knows another instructor who does still teach it.

 

[Lost Yooper]

Sounds like you have a decent instructor there -- congrats! I'll get those links together and send you a PM. Hopefully, TDI will phase out deep air and help change the attitude of the industry.



Mike

 

[dc4bs]

Thanks LY.

I'll keep an eye out for the PM.

 

[WYDT]

Sounds like your friend is a Moron!

I don't say that to be an "A" hole but with all the info out there now I'd have to say it's nothing but idiotic to do "deep air"!

I personally wouldn't dive with someone who wanted to take a deep air class! Maybe if you really want to get the point across tell him if he takes that class that you won't dive with him again.

Just an idea. Good luck!

DSAO!

 

[Uncle Pug]

Well perhaps those links and studies will convince your friend but I kinda doubt it....

So here is something that might convince him....
(This will take cooperation from your deco TDI instructor)

Do a modest dive within NDL to the recreational limit of 130 on air....

Do the same dive on 30/30....

Compare....

Not the narcosis level during the dive...
But the way you feel after the dive...

 

[AquaTec]

DC4BS

If you read Yoops stuff and try UP's tests it will convince you.

They convinced me, even though i would still do a single dive to 130 on air. [i know i know, but im an old dog learning new tricks]
a month ago i would have said a 200ft dive on air, I have only done about six dives since I started experimenting with their theories.

On dives between 150 and 200 there is a deffinet defference in my body physicaly. between 100 and 150 I feel the same.
I now set my END at 100 as those dive are more complex and I want to reduce some of the complexities ie high PPN2 based on the material that Yoop offered, there is no real down side in doing this that I can see, a little longer deco time but not much