George,

Sorry about taking so long to get back but my companies email system has
been down from Thursday until now on Sunday.  What I was referring to in
particular is the CNS clock, not that toxing isn't a real issue.

Thanks for the info!

Art.

	-----Original Message-----
	From:	kirvine@sa*.ne* [SMTP:kirvine@sa*.ne*]
	Sent:	Thursday, December 30, 1999 9:41 AM
	To:	Paltz, Art
	Cc:	Shimell, David (shimell); QUEST@GU*.CO*; techdiver
	Subject:	Re: SAMPLE DECO DIVE - 220 FOR 25

	Sure , Art - the only two issues are that 1) Navy found an increased
	chance of toxing after multiday elevated ppo2 exposures ( like
nitrox
	diving every day or deco diving every day ) with the MK16 divers,
and 2)
	the lung damage and such are obvious and cumulative. The lungs tend
to
	scar and build "callusses" , decreasing vital capacity.

	Art , I do not know what I said about anything  being bullshit
unless it
	is what the agencies teach, and that is solid bullshit, but I take
	oxygen exposure very, very seriously, and to me it is the biggest
risk
	in tech diving outside of violating Rule Number One.


	Paltz, Art wrote:
	> 
	> George,
	> 
	> Can you elaborate on Oxygen Exposure?  I remember you saying many
times that
	> OTU's and CNS clock's are BS.  How do you track this?  What about
repetitive
	> dives?
	> 
	> If you covered this before in the thread I apologize, I must have
been
	> snoozing...
	> 
	> Thanks,
	> Art.
	> 
	>         -----Original Message-----
	>         From:   kirvine@sa*.ne* [SMTP:kirvine@sa*.ne*]
	>         Sent:   Wednesday, December 29, 1999 2:26 PM
	>         To:     Shimell, David (shimell)
	>         Cc:     QUEST@GU*.CO*; techdiver
	>         Subject:        Re: SAMPLE DECO DIVE - 220 FOR 25
	> 
	>         I ignore the first dive - in this case you have mushed the
bubbles
	>         anyway. After enough time, I ignore any first dive other
than as
	> regards
	>         the oxygen exposure - that is where the risk lies.
	> 
	>         Shimell, David (shimell) wrote:
	>         >
	>         > George
	>         >
	>         > Here's another question.
	>         >
	>         > Say you do your 220' for 25 and then ascend to do a
multi-level
	> dive to say
	>         > 90' for 25.  How would you calculate the deco for this?
I recall
	> you once
	>         > talked about superimposing one table on another but I
had it on my
	> list of
	>         > things to look at.
	>         >
	>         > David Shimell
	>         > Email: shimell@se*.co* <mailto:shimell@se*.co*>
	>         > Project Manager, IBM NUMA-Q, Sequent Computer Systems
Limited,
	>         > Weybridge Business Park, Addlestone Road, Weybridge,
Surrey, KT15
	> 2UF, UK
	>         > registered in England and Wales under company number:
1999363,
	> registered
	>         > office as above
	>         >
	>         > -----Original Message-----
	>         > From:   kirvine@sa*.ne* [SMTP:kirvine@sa*.ne*]
	>         > Sent:   Friday, December 24, 1999 12:43 PM
	>         > To:     QUEST@GU*.CO*
	>         > Cc:     techdiver
	>         > Subject:        SAMPLE DECO DIVE - 220 FOR 25
	>         >
	>         > Let's run through a sample dive. I will throw out the
parameters
	> and
	>         > the standeard deco on one side, and my changes and why
on the
	> other ,and
	>         > then we can discuss it.
	>         >
	>         >  We can then build the dive into a longer dive, a deeper
dive and
	> we can
	>         > add more gasses and more stituations, and then the
equipment to do
	> it.
	>         >
	>         >  Let's start with this and get the discussion going that
way. I
	> need all
	>         > questions, no matter how sophisticated, so we can get
out the
	> rock.
	>         >
	>         > ***PROFILE 220 FOR 25                   CHANGES
	>         > ***GAS 16% OXYGEN  50% HELIUM   1.2 PPO2
	>         >                                 85 AED
	>         >
	>         >          REASON FOR GAS CHOICE: the more heluim, the
better . It
	> is
	>         > easier to breathe at depth, and it is easier to
decompress from,
	>         > contrary to what you have been told elsewhere. The
reduced narc is
	>         > obvious. I chose the 50% heliuum for this , but the more
the
	> better. The
	>         > oxygen ppo2 should be kept intentionally low. The reason
is that
	> you do
	>         > not want to unnecessarily deplete brain chemistry to
pick up
	> "perceived"
	>         > deco advantage, expescially in light of the fact that we
have
	> boosted
	>         > the helium which reduces the nitrogen damage and
loading, and thus
	> the
	>         > deco requirement. While inert gas is inert gas for
purposes of
	> this
	>         > discussion ( or said another way, the oxygen window is
the oxygen
	>         > window) the reality is that helium changes the
physiological
	> factors
	>         > that are as real in deco as the straight compartment
loading and
	>         > unloading factors. Very important to us in our diving,
and more so
	> as
	>         > the dives get more severe or repetitive. We also do not
want to
	> burn the
	>         > shit out of our lungs with high PPO2's either, and keep
in mind
	> that
	>         > depending on the bottom time, we are going to be forced
to expose
	>         > ourselves ot elevated oxygen to decompress.
	>         >
	>         > It is critical in multiday exposure that you reduce the
oxygen
	> dose, and
	>         > we will show how to do that in each decompression.
	>         >
	>         > STANDARD DECO FROM A PROGRAM            REAL LIFE DECO
	>         >
	>         > DEPTH   TIME    GAS                     DEPTH   TIME
GAS
	>         >                                         160-120 1 MINUTE
EACH ON
	> BG
	>         > 110     1       16/50                   110     1
	>         > 100     3                               100     1
	>         > 90      4                               90      1
	>         > 80      5                               80      1
	>         > 70      3       50/50                   70      5
50/50
	>         > 60      4                               60      2
	>         > 50      5                               50      3
	>         > 40      9                               40      5
	>         > 30      11                              30      8
	>         > 20      17      OXYGEN                  20      13
OXYGEN
	>         > 10      26                              20-0    8
	>         >
	>         > TOTAL 88                                TOTAL   60
	>         >
	>         >                     REASONS FOR CHANGES
	>         >
	>         > 1) we start our deco at 80% of the profile in
atmospheres, or in
	> this
	>         > case , around 160 feet. We are not changing gases yet,
so no
	> reason to
	>         > sit on these stops. The ascent rate is 30 fpm, or the
equivalent
	> of a 20
	>         > second stop every ten feet from the bottom, so we are
really only
	> adding
	>         > 40 seconds per "stop" from 80% of the profile. This
actually
	> "maxes out"
	>         > at about 5 minutes per "deep stop" in anything
approaching
	> saturations,
	>         > which I call 150 minutes for the purposes of
decomprssion reality
	> as
	>         > opposed to trying to decompress a whale. In a long dive,
we also
	> use the
	>         > first deco gas at 80% of the profile . Not in play here.
	>         >
	>         > 2) moving up we do not extend these stops per Bulhmann,
since we
	> have
	>         > already moved the "ceiling" quite a long ways above us,
and are
	> not yet
	>         > really pressing the gradient ( in percentage or relative
terms, ie
	> the
	>         > ratio of the atmospheric change deep a opposed to
shallow). We
	> need to
	>         > get to a deco gas first and spend some time, so......
	>         >
	>         > 3) we "SIT" on the 70 foot stop for quite a bit longer
than is
	> suggested
	>         > by theory. The reason is we want to use that wide open
oxygen
	> window for
	>         > all it is worth down there to both clear the slate as
much as
	> possible,
	>         > and to move that ceiling again quite a bit so that we
can
	> abbreviate the
	>         > stops above as their ppo2 declines, rather than
lengthening them
	> as
	>         > either Bulhmann or bubble mechanics would indicate -
real life
	> says we
	>         > are correct. In fact, I have SKIPPED up to 100 minutes
of our 40
	> foot
	>         > stops with no repercussions, and Lucy Ho can vouch for
me on this
	> ( and
	>         > the doppler says so). The other reason is that we want
to give the
	> blood
	>         > a chance to totally circulate with the new gas. While it
hits the
	> key
	>         > body parts immediately ( spine, heart, brain), it takes
a couple
	> of
	>         > minutes to get to everything properly. We do not want to
hammer
	> high
	>         > popo2's, we want to use them to our advanntage.
	>         >
	>         > 3) since we have done our deep stops and our high
ppo2's, both
	> moving
	>         > our ceiling and shortening our upper time, we can go
ahead and
	> press the
	>         > gradient as it condenses, and shorten the next few stops
and get
	> to that
	>         > oxygen.
	>         >
	>         > 4) the oxygen does not have to be hit too ahrd. I like
12-13
	> minute
	>         > stints with 6-8 minutes off. The reasons are that it
takes almost
	> no
	>         > time to saturate with oxygen at any ppo2 once the
immediate
	> offgassing
	>         > slows - a few minutes - and the damage starts to accrue
after
	> about
	>         > 16-20 minutes in our experience, depending of course on
the
	> dosages
	>         > already taken on the way up to this point.  The swelling
of the
	> lung
	>         > tissue picks up after a few minutes, and the gas
transfer process
	> is
	>         > severely hampered. Vasoconstriction gets worse, and you
are
	> pissing in
	>         > the wind honking on the oxygen. You need to break to
back gas, or
	> in
	>         > this case , just move up and get out.
	>         >
	>         > 5) slow final ascent - the last move up to the surface
is one of
	> the
	>         > most critical. No matter how long you sit on a stop with
the
	> window wide
	>         > open, there will still be gas that will not be displaced
by this
	> method.
	>         > When you increase the gradient by trying to surface, the
last of
	> the gas
	>         > comes out rapidly and does so in bubble form. You must
do a slow
	> ascent
	>         > to reduce the risk of this, and for long dive it is one
foot per
	> minute
	>         > to the surface, for this dive it is more like 2.5 - 3
fpm.
	>         >
	>         > 6) at the surface, sit still for a bit and try not to
exert for
	> about 30
	>         > minutes thereafter. Bubbles forming at this time will
now grow as
	> they
	>         > pick up offgassing nitrogen ( the helium is long gone)
and will
	> become
	>         > problematic later, and severely so if you have a shunt
that can
	> then be
	>         > opened by the in increasing pressure on the cappillary
beds of the
	>         > lungs.
	>         >
	>         > OK - let's take it from here and get the discusion
going.  Please
	> do not
	>         > copy back the whole message or it will become a mail
bonb - just
	> cut and
	>         > paste the parts you want to discuss, and lets discuss
one item per
	>         > email, SVP. When we expand this to a long dive, then I
will cross
	> copy
	>         > it to WKPP@eg*.co*, and we will bring in the big
guns ( Rose,
	> Mee
	>         > ,et al).
	>         >
	>         > Let's go .
	>         >
	>         > --
	>         > Send mail for the `techdiver' mailing list to
	> `techdiver@aquanaut.com'.
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	> 
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