Raphael Warshaw wrote:

One issue that I haven't seen mentioned in these posts is the fact
that demand end-tidal pulse devices like the Mountain High assume that
you are breathing through your nose.

Only when you are using a cannula. If you use a mask, as required by the
FAA above 18,000', you may also breathe through your mouth. A mask
should have come with your EDS unit.

They also assume that you clear
the physiogical dead-space sufficiently with each tidal breath to
deliver a reasonable concentration of O2 to the alveoli.

I don't even know what "demand end-tidal" and "tidal breath" mean, but I
think they assume you take a normal breath, rather than a shallow one.
Is that what you mean?


The only mammals I'm aware of that are obligate nose-breathers are
rodents, so, unless you're a rat, you've got one more reason to use
that oxymeter.

The Nonin Company showed some neat recording oxymeters with alarms at
a meeting I'm attending and at least one company showed a combination
ECG monitor and oxymeter on a single PCMCIA card which fits in the
accessory backpack of an IPAQ. These devices cost less than a grand.
A bit of programing should be capable of integrating this information
and alarm ranges based on it with existing flight software like
Winpilot which more and more folks are using as primary flight
displays. If you store the information, you've got a cheap, quick and
dirty research project.

The Minolta Pulsox3 series is available with recording and alarms for
about $750, the last time I checked (www.minolta.com).

There's no doubt that pressure-demand systems using fitted masks are
the way to go for flights to high altitude(18,000 feet).

Are these systems supplying oxygen in the mask at above ambient
pressure, even at low altitudes (18,000-24,000 feet)?

My concern
is with what happens down low (between 5,000 and 18,000 feet). My
suspicion and concern is that more than a few pilots are, at
relatively low altitudes, desaturated sufficient to experience
measurable performance decrements.

Pat McLaughlin, the owner of Mountain High oxygen, told me they first
realized that when they began selling oximeters. Some people would call
to complain the oximeter wasn't working properly, but the usual reason
turned out to be their low saturation at low altitudes (like in Florida,
in a particularly bad case).

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Eric Greenwell
Washington State
USA