Posted by davrecon-3 on
URL: https://www.shado-forum.com/Air-supply-tp1505209p1505284.html



----- Original Message -----
From: "Gene R. Dahl" <[hidden email]>
To: <[hidden email]>
Sent: Sunday, February 06, 2005 9:22 PM
Subject: Re: [SHADO] Air supply.


>
> I agree with everything you wrote except for the following:
>
> davrecon wrote:
>
> > Your body is actually un-able to detect the lack of oxygen in the air
it
> >breathes, it only goes by the CO2 content to regulate respiration. So if
you
> >were to rebreath the same air, but only scrubbing out the excess CO2
w/out
> >replacing the oxygen, you would simply pass out, blissfully unaware that
you
> >were suffering from oxygen starvation. Many inexperienced general
aviation
----------------------------------------------------------

Maybe perhaps "un-able" was the wrong choice of words right there. But
the O2 levels is an automatic and unconscious regulator, it's like the body
is altering it's responce without necessarily notifying us as the conscious
person.... Whereas the CO2 level is a very conscious and alarming one.

Even using the above, would that scene with Col. Gray suffocating in
the moonbase sphere make sense with him clutching and grasping at his
throat? He would have just continued sleeping peacefully until he expired.

When we were in the altitude chambers and they were taking the air away
from us, we never felt the lack of oxygen in the distressing way that we
felt CO2 build-up. If the guys were breathing faster (from O2 triggered
hyperventilation as you say), they, and I, never really noticed it because
of the general feeling of well being we usually seemed to feel, at least
until they taught us what to look for in ourselves. The cues were all
subtle. Unless an instructor actually went over and placed the mask back on
a recruit's face, he would simply flounder and giggle before he passed
out....but the guy always seemed happy, uncaring, and undistressed over his
situation.

The body's CO2 alarm is so much more visible and distressing to us than
lacking oxygen, which is the way our manuals and the flight surgeons also
used to explain it to us. The O2 regulation seemed more based on the body's
metabolic need (like from running or increased physical excertion) than an
emergency response ("Oh My God, I Can't Breath!!!" .... Claw For Air). If O2
levels fell short, for whatever reason, we simply faded out and eventually
collapsed. If CO2 levels build up, we feel a very immediate and unpleasant
reaction and severe distress.

In the Navy, sailors are taught to enter long sealed and unused void
spaces in ships with caution, because if oxygen levels are depressed in
there, they can collapse inside there and die undetected. Why? Because the
body will not alarm him that he is in an oxygen insufficient environment.

Divers are cautioned against using Nitrox and other oxygen enriched
mixures at greater depths because of the poisoning effects of excess O2, and
pilots are cautioned against operating at high altitudes without supplement
because of inadequate O2, because damage is inflicted, or your facilities
are impaired without your awareness of it. That is why people need special
training in dealing with it as a safety issue, whereas nobody needs to be
taught how to react to being smothered - if the CO2 builds up in your blood
you know it right away and with a vengence.

Dave H.