Sender: <marv@lancaironline.net> (Marvin Kaye)
To: lml
Date: Sat, 04 Oct 2003 22:09:40 -0400
Message-ID: <redirect-2624407@logan.com>
From: "Ted Noel" <tednoel@cfl.rr.com>
References: <list-2622613@logan.com>
Subject:  Re: Oxygen
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>
> Lack of oxygen is not sensed by the body. What happens when we feel "short
> of breath" is that the body responds to excess of CO2 to tell the brain
that
> there is an oxygen shortage. This worked well on the African savannahs,
but
> where the oxygen is thin, the CO2 never gets excessive.

This is only partially true. 90% of the population will get short of breath
with hypoxia. I speak from experience from an occasion where I got
pneumonia. I got short of breath, and nasal O2 fixed it. There is a body of
research on this in the Altitude/Mountain Sickness (AMS) problem. The 10%
that don't properly sense hypoxia are the ones who are particularly
sensitive to AMS. My wife is one.
>
> In the 1930's when all this was being worked out, it was claimed that
> providing the aviator with 3% CO2 (!) would allow him to fly at 17k with
the
> mental performance of 12k. I leave it to flight surgeons to puzzle this
> out---my guess is that it is true.

It is true. It acts as if you held your breath. It makes you so short of
breath that you hyperventilate to reduce your CO2. In doing so, you actually
reduce your CO2 enough to leave "room" for more O2. I won't bore you with
the alveolar gas equation and the difference between arterial and venous CO2
on that one. In treating AMS, we give a medication that makes your blood
more acid. This tricks the chemoreceptor in your brainstem into thinking
that your CO2 is high. This makes people breathe faster to reduce CO2, which
is the normal response to high CO2. It is also the normal response to
hypoxia, but is missing in that 10%.
>
All said, supplemental oxygen is the proper answer.

Ted Noel MD
Lancair 4-P 98%
N540TF