This posting started very well, factual and informative. What a shame it had
to end yet again with totally inappropriate venom spitting.

Bernhard Weber, Germany.

----- Original Message -----
From: "George Irvine" <trey@my*.ne*>
To: "The McLeods" <rmmacleod@ac*.ca*>; "techdiver"
<techdiver@aquanaut.com>
Sent: Friday, September 06, 2002 09:27
Subject: RE: O2 exposure


> 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" <rmmacleod@ac*.ca*>
> 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
> to deco properly,my deco's are going very well,I feel much better when
> getting out of the water.My question is this:when using O2 for deco,how
>
>
> -----Original Message-----
> From: The McLeods [mailto:rmmacleod@ac*.ca*]
> Sent: Wednesday, September 04, 2002 5:12 PM
> To: techdiver
> Subject: O2 exposure
>
>
>     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
> to deco properly,my deco's are going very well,I feel much better when
> getting out of the water.My question is this:when using O2 for deco,how do
> the cave guy's control their O2 exposure on those incredibly long
> dives.Using deco-planner for instance,it does not take long to exceed max
O2
> limits,even when taking into account the back gas breaks.How is this
> accomplished safely,aside from using a habitat?
>
> Randy
>
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