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From: <caccioly@ir*.co*.br*>
To: kirvine@sa*.ne*
cc: techdiver <techdiver@aquanaut.com>
Date: Wed, 25 Aug 1999 12:33:38 -0300
Subject: Re: [Fwd: Stiffness at depth]
This is great info! Now *this* is why I log onto these lists.

One question, though: how can anti inflammatories help
against osmosis drawing synovial fluids out of your joints?
I'd think it can't help. The obvious conclusion would be that
you're still taking quite a beating whenever you dive deep.

Best,
Carlos






kirvine@sa*.ne* on 08/23/99 22:07:24

Please respond to kirvine@sa*.ne*
                                                              
                                                              
                                                              
 To:      techdiver <techdiver@aquanaut.com>                  
                                                              
 cc:      (bcc: Carlos Accioly/Ipanema/isa)                   
                                                              
                                                              
                                                              
 Subject: [Fwd: Stiffness at depth]                           
                                                              






Forward from Hans.



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Date: Tue, 24 Aug 1999 02:19:57 +0200
To: kirvine@sa*.ne*
From: Hans Petter Roverud <proverud@on*.no*>
Subject: Stiffness at depth
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At 06:33 AM 8/23/99 -0400, you wrote:
>Richie is talking about something else with the stiffness. What you are
>talking bout is baratrauma, and the joints get it from working under
>high pressure.
>
>We conserve our motion to reduce this, and use anti inflammatories.
>
>What we are discussing is that feeling like you get from dehydration,
>lack of potassium or hypercapnia. Anyone havae any ideas on that?

Hi George!

For some reason the techdiver server has been kind of funky lately. I've
tried to post several times, only to receive some error message. Still, I
get all the messages.

Stiffness: Osmotic imbalance during rapid descents causing synovial fluid
to be drawn out of the joints.

Reason: As ongassing occurs in fast tissues first, their osmolarity
increases. A gas load makes tissues draw water from tissues with a lesser
gas load. This is just like salt(er) water drawing water from fresh(er)
water.

Result: Joints are temporarily going dry (drier). This leads to lack of
"lubrication" and pain.

Eventually, as the entire body reaches / approaches saturation this osmotic
imbalance levels off. Sat divers get slight joint pain at 330' upon a fast
descent. However, after half an hour's stay at this depth they're fine
(equilibrated) and may proceed to greater depths.

Other quips:

On the cold water -- helium thing:
It's all about heat capacity versus heat conductance. Helium has a lower
heat capacity than air and a much higher heat conductance. Since the gas
you inhale will be heated to body core temperature anyway, a higher
conductance makes no difference. The real issue is the caloric price of
heating it (heat capacity) which is somewhat LOWER for helium than for air
/ nitrox. Conductance, on the other hand, is the main issue when you use a
gas as an insulator. That's why helium is bad in a dry suit -- it doesn't
cost much to heat the helium, yet it's constantly drawing (conducting) heat
from your body to the water.
Bottom line: it's NOT colder to breathe helium than nitrox, but NEVER use
it for suit inflation!

On counter-diffusion:
The problem is to breathe air or argox while in a helium atmosphere. Since
we do it the other way around -- breathing helium mixes in an argon (suit)
atmosphere there's no problem.

On mitral valve defects:
The only defect that will increase the susceptibility to DCS is the one
causing blood to bypass the lung filter. The congenital left-over from
fetal circulation -- patent foramen ovale -- is the only defect that will
cause this.

regards,
Hans






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