Thanks, I'd heard other people talk about tightening
the backup reg necklace also.  I'm going to double
check mine today.
The 10 minutes on low O2 before exiting the habitat is
a good piece of information, too.
Just the kind of ideas I was hoping for!
Thanks again.
Wendell
--- George Irvine <trey@my*.ne*> wrote:
> Wendell, my guess is that the buddy needs to be
> ready to surface the guy
> after a seizure, but could try positioning himself
> so that he could hold the
> guy's reg in if needed. On a dive where you would
> expect this to be a risk,
> FFM's would be on hand, and what we do for "peace of
> mind", since as you so
> accurately point out, stress and fear will
> potentiate tox, we have the
> backup reg necklace tight enough so that if you go
> to the backup and put the
> elastic up around the head, it holds that reg in
> place. Maybe it will work,
> maybe not, but the peace of mind works.
> 
> Going to the lowest breathable PPO2 gas is the first
> move you make. The
> problem with tox is that there is generally no
> warning, and it can occur as
> much as ten minutes after you are no longer
> breathing the offending gas.
> This is the genesis of that bullshit "off oxygen"
> effect. What we do, having
> known about this for 15 years, is go to a very low
> oxygen mix for ten
> minutes prior to exiting any habitats.
>   -----Original Message-----
>   From: wendell grogan [mailto:docgrog@ya*.de*]
>   Sent: Friday, September 06, 2002 3:18 PM
>   To: George Irvine; The McLeods; techdiver
>   Subject: RE: O2 exposure
> 
> 
>   Along these lines, what is the recomended course
> of action if someone
> finds themselves starting to experience oxtox
> symptoms, or if they think
> they may have a dangerously high ppO2 exposure (for
> whatever reason)?
> 
>   Since stress reactions (read panic) and high CO2
> levels increase your risk
> of taking a CNS tox hit, how do you get out of the
> situation?  Another side
> to this is that this is not a strictly a
> depth/pressure related phenomenon
> so that getting to a shallower depth quickly is not
> a sure solution.
> 
>   Obviously, having an attentive buddy is a major
> factor, but the question
> then may be what should the buddy do (assuming he is
> aware that something is
> going wrong before you start doing the five fathom
> funky chicken)
> 
>   Wendell
> 
>    George Irvine wrote:
> 
>     Oxygen exposure has cumulative risks and spike
> risks, as well as
> temporary
>     and longer-lasting damage risks. The basic ways
> to minimize these is to
> 1)
>     reduce ppo2 for longer dives while increasing
> helium content, reduce
>     overall ppo2s for repetitive or multiday diving,
> including starting deco
>     gases at a shallower depth than usual, 2)
> interrupting exposure with
> breaks
>     to a gas that gives the lowest breathable ppo2
> on regular intervals, and
> 3)
>     using the correct gasses at deeper deco stops to
> as to reduce the need
> for
>     longer times at shallower stops.
> 
>     Keep in mind that bends risk is in now way
> equivalent to death risk.
> keep
>     in mind that spiking ppo2s on top of an extended
> exposure to already
>     borderline ppo2s is deadly. keep in mind that
> jumping to a high ppo2 gas
>     deep is idiocy and absolutely unnecessary.
> 
>     Oxygen in higher ppo2s causes the body to try to
> defend itself, and
> those
>     defensive mechanisms include adding cell layers
> to the interface,
>     vasoconstriction to reduce transmission,
> swelling of the lung tissues
> and
>     fluid accumulation to defend, and other immune
> responses, all of which
> are
>     counterproductive to gas exchange. These
> reactions onset within 12
> minutes
>     and in no more than 20 minutes to some degree or
> other. Preventing them
> is
>     easier than reversing them.
> 
>     When you 'toggle" the gasses back and forth, you
> are reducing these
>     responses and actually increasing the ability to
> eliminate unwanted
> gasses,
>     while at the same time allowing brain chemistry
> to keep up with the
>     stresses, thus postponing any critical event
> that might cause a tox.
> 
>     We do these things on a carefully prescribed
> basis. Only one of our dive
>     sites allows for a habitat, and at that site we
> are merely able to do a
>     higher ppo2 with a 12 on, 6 off protocol, then a
> 10 minute cleanup
> break,
>     then an ascent to the surface at 1 foot per
> minute on no greater than
> 50%
>     gas for the first 12 feet. We have safety divers
> on each decompressing
>     diver. We are also getting a huge advantage
> being in air for that part
> of
>     the deco, rather than in water.
> 
>     For the rest of our sites, we are doing
> conventional inwater deco. There
> we
>     really have to be meticulous about exposure. On
> any of the long dives,
> we
>     do the entire last step of a gas on backgas (
> ie, the 120 bottle would
> be
>     used from 120-90 and then the 80 stop would be
> on back gas). We also
> take a
>     20 minute cleanup break at 50 feet on backgas
> and finish the stop on
> 50%.
> 
>     15 years of WKPP experimentation with protocol
> and gases went into our
>     methods, and we validate them with bloodwork and
> doppler, not to mention
>     results.
> 
>     Aside from Rule Number One violations, the most
> dangerous aspects of
> diving
>     are 1) driving to the site, 2) decompression on
> high ppo2s.
> 
>     Separately,---
> 
>     I see this drooling idiot JT has weighed in on
> the discussion. This
> person
>     is a total idiot, and so are his dive buddies.
> They want so badly to be
>     recognized - well they are - as morons. They
> can't dive, they know
> nothing,
>     they have big mouths and big egos ( undeserved,
> they have no real
>     experience, no methods worth discussing, no
> validation of anything but
>     stupidity, and they are extremely dangerous.
> Avoid these people at all
>     costs. My best advice, and you all know when I
> was last wrong about
>     something like this - never. these guys are
> monkeys with an attitude.
> There
>     are only two or three of them left with the
> "captain", and my bet is
> that a
>     more serious form of attrition will eventually
> prevail.
> 
> 
>     From: "The McLeods" 
>     Subject: O2 exposure
>     Date: Wed, 4 Sep 2002 18:11:32 -0300
>     Now that all the bantering has ended,I have a
> serious question for
>     George regarding O2 exposure.After following all
> of G's instruction on
> how
> 
=== message truncated ===


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