The last time I suffered a stiffness at depth was when I was thinking 
about Christina Young during a wreck dive.

 Jim

Sender: Rich Lesperance  Date: 8/24/99 11:58 PM

>Hans,
>
>Thanks for this excellent description. From my (admittedly limited)
>knowledge of physiology, this explanation (of the joint stiffness) makes
>perfect sense.
>
>And to the Miss Manners types out there - THIS is what you should be getting
>from (or giving to) the list, not etiquette lessons.
>
>Rich L
>
>
>
>----- Original Message -----
>From: Hans Petter Roverud <proverud@on*.no*>
>To: <kirvine@sa*.ne*>
>Sent: Monday, August 23, 1999 8:19 PM
>Subject: Stiffness at depth
>
>
>> 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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>


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