George, I have listened to what you have said over the years, I was trying
to look at it from point of view of quantifying it. My thoughts were really
just academic. It would be interesting to look at the RBC changes over a
partial pressure gradient, to see the onset of the rigidity.  Just a thought
for someone looking for a PhD project.
Let me out of here B4 I bury myself!
Jeff the Darwinian............heard a rumour about May / Sydney.
----- Original Message -----
From: "George Irvine" <girvine@be*.ne*>
To: <swanncruz@oc*.ne*.au*>; "George Irvine" <kirvine@sa*.ne*>;
<techdiver@aquanaut.com>; <quest@gu*.co*>
Sent: Monday, February 11, 2002 9:09 PM
Subject: RE: Red Blood Cell Rigidity


> Narcotic level is easy - any increase is more narcotic than no increase.
> Impairment starts immediately, and just gets worse.
>
> As for rigidity due to nitrogen tension, it appears to be relieved by the
> presence of helium in the same fashion - the more helium , the less
tension.
>
> We have found that <30% is not going to do a whole lot . 25% is the
minimum
> useful range for deco gas, 30 for diving, and then we are talking <120
feet.
> For all else we go to at least 35 and prefer higher.
>
> After thousands, as in the tens of thousands, of man dive hours in the
WKPP
> doing extreme exposure mixed gas dives over the course of 16 years , and
> intensely over the last 9 years, these have been our findings.
>   -----Original Message-----
>   From: swanncruz@oc*.ne*.au* [mailto:swanncruz@oc*.ne*.au*]
>   Sent: Monday, February 11, 2002 3:03 AM
>   To: George Irvine; techdiver@aquanaut.com; quest@gu*.co*
>   Subject: Red Blood Cell Rigidity
>
>
>   "High partial pressures of nitrogen cause the red cells to become rigid
> and
>   get hung up in capillaries or damage them. The response of the body to
> this
>   and the immune response tend to close off the area . Anyone ( but a dive
>   instructor) can see what that means for decompression."
>   Hi George & List,
>   As always, thanks for the info.
>   With respect to red cell rigidity with a high pp of N2, my knowledge of
> physiology has dulled somewhat over the years, but red cells do distort
> (squash) as they move through smaller capillaries, which would make the
> prospect of increased rigidity of the RBC quite alarming. That is, small
> capillaries are smaller than RBC. Hence, it could be that we see RBCs
unable
> to pass and associated capillary rupture.
>   Do you think there is a threshold partial pressure where the effect of
RBC
> rigidity becomes marked, or is there a linear change?
>   I would think there would be an age variable here as well.
>   If so, did this (theoretical) threshold partial pressure of N2 (causing
> BBC rigidity) influence the GUE recomended mixes?
>   I realize you are keeping the narcotic values at around or less than
30m.
>   What I am getting at is a "threshold physiologically damaging pp of N2",
> as well as a narcotic level.
>   We seem to be able to quantify a narcotic value (=level).
>   This is fascinating stuff, and would keep some PhD students going for
> years.
>   Regards,
>   Jeff the Darwinian.
>
>   I'm going to send this quick, B4 I confuse myself any
further.............
>
>

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