HELIOX where to find information?

Mikel-Deko

Why diving trimix and decoing heliox? this way you have to deco two gases.
It is not more simple just saturate of one gas,He, and deco this gas?
The deco time can be longer but the posibility of N2 bent is gone.
The only problem that i can see is that there are not tables or algorithm very good tested with heliox or are they?

Regards

Mikel-Deko

Mdemon

To re-state the concept I was thinking about, and we are talking 'bouncing' extreme depths:

- Dive very, very deep (including HPNS depths) on trimix.
- Dive with a high END
- Switch to heliox either immediately on the turn, or where off-gassing is predicted to start.
- Ascend using a high setpoint - 1.4, 1.5 - all the way up

Possible benefits?
1) Reduce the amount of helium ongassed at depth
2) Nitrogen helps to reduce the effects of HPNS at depth
3) Nitrogen is slightly more forgiving (as it offgasses slower) so accuracy of stops isn't so critical - you have time to put things right
4) The nitrogen in the slower tissues should be out by the shallow stops because of the gradient. However the pressure gradient remains so excessive bubbles shouldn't form (****this is the bit I am asking about, I'm just not sure about this at all!!!)
5) The high setpoint increases the gradient and speeds the offgassing of inerts. (It may also partly "treat" any tissues damaged on the way up by keeping the O2 levels in the surrounding tissues high...)

It's not really about reducing the deco, because as has been pointed out, this is unlikely to happen due to the switch to heliox. The high setpoint will have more effect on reducing the deco time per se. It may however be a more efficient deco.

It's 4) that I'm interested in here. Rats saturated in air at pressure and decompressed using heliox (e.g. 50:50) had bubbles reduce quickest, and without the temporary increase that 100% O2 caused. Now, rats aren't humans and other animals like goats are a closer match ( ), but it seems to me that if a Nitrogen-rich to helium-rich gas swap was a "bad thing" and caused ICD-type problems, the rat experiments would have shown different results. (This is why the Comex30 table uses 50:50 heliox IIRC)

The trouble is, it's all well and good reading lots of medical papers online, but stitching the results together to validate a technique is beyond me - I'm hoping a hyperbaric doctor on here might have some opinions...

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"Once the agenda-monkeys and perfect-worlders have moved on, perhaps we can do some diving?"

DrJM

Disclaimer: I'm not at all expert in decompression medecine, what I am doing is purely empirical and I accept the risk BUT it could easily KILL YOU!

Using Heliox ? oh yes but:

Low ppo2 on descent (1,2-1,3) to avoid O2 spike in the loop

High ppo2 on ascent +/- 1,5

ALWAYS (even shallow dive) pure O2 from -6 (or -12 max if deco habitat)

Descent rate < 30m/min and heating jacket ON against muscle tremor/shivering (kinda HPNS)

Deco based on VR3-VPM and soon on Ouroboros-VPM

backup table done with VPM-B-E coef +5

Will see some of you guys at the LIDS from 1pm to 4pm (will attend Rick speach about Wookey and Italy)

Jerome

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Mikel-Deko

But do you use the same system (Deco, descent rate, heater on, etc) in your 70 -100 mtrs dives? wich gases?
Thank you very much
Regards
Mikel

DrJM

Well maybe not the heating jacket

Gases related to target max depth, usually ppo2 1,3-1,4 like that in case of spike of O2 on descent or hyperoxia due to CCR malfunction I can flush the loop (minimum 3 times) to drop the ppo2

PS for the guys around London or the M25 (or just coming to the dive show; or going in France cave or wreck diving):
Before the Dartford tunnel go to the new diving center "Lakeside diving" run by Kevin Side ==> Helium at £0,009 / lit and you can just top off your 3 or 20 lit tanks if you want or get a full tanks of 5/95, Kev's got big Haskell Booster

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Mikel-Deko

Thanks you very much Dr. Jerome.
We are preparing for this year some deep dives 70-110 mtrs.

Talking about gases, both of us, agree that Heliox will be better than Trimix, but, when we went to our computers to make some Heliox tables, we realized that there weren't good enaught.

Now, we have some things clear.

Thanks you very much.

Regards

Mikel-Dekox

J. V.

What program do you use ?

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Jacques
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Mikel-Deko

VR3 v2.1CXR (DivePlan) and PRO-DIVE 7.12C

I've also V-Planner v3,10. Thil now i didn't like it very much.

Playing with the VPM-B Model of the V-planner with Heliox and after this disscusion, i'm thinking that it can be a good enaught program.

I've a friend with a Evolution. It uses the VPM algorithm and we are trying out some tables to compare. Do you have any information about the Evolution software?

Regards

Mikel

decoweenie

If you are referring to the APD Evolution unit, it uses GF - not VPM.

Mikel-Deko

Thanks you very much.

We mistundestood each other

Anyway, we will tried the GF algorithm to compare.

Regards

Mikel