Thread: Oximeter's
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Old November 24th 05, 03:18 AM posted to rec.aviation.owning,rec.aviation.piloting,rec.aviation.student
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Default Oximeter's

Hai Longworth wrote:

Yeah, it's a nice thing to have but not essential to the pilot's
health or safety except the extreme cases.


I'll disagree about "only in extreme cases". For a long time, I was
willing to fly at 12.5K ft without using O2. Every once in a while I'd
turn it on if I was feeling very tired, or was yawning a lot, and once
at 13.5K ft I THOUGHT I had turned it on, but hadn't, for a 2 hour leg.
I now think that having a pulse oximeter is an extremely useful tool to
tell you how well YOU'RE performing - we monitor the heck out of the
planes, but don't do a very good job of monitoring ourselves. The SpO2
monitor is a way of doing just that.

At any rate, here's a message I posted to the COZY mailing list
regarding an experiment (not controlled, but interesting nontheless) I
did earlier in the week:


We had previously had a discussion about SpO2 levels vs. time at
altitude.

So I flew to Las Vegas from Mojave today to pick up my wife, coming home
commercial. I took a different route - through the "Trona" gap, over
L72, and just south of China Lake. It's faster (more direct), but I had
to go higher to avoid mountains. On the way there, I decided to use my
SpO2 sensor to watch my O2 levels as I climbed without supplemental O2.

As I passed through 8K ft., I put on the gizmo. My SpO2 levels were in
the low 90's, and when I leveled out at 9500 ft., within a couple of
minutes at the most my SPO2 levels evened out at about 87%. Not great,
but OK for a while. After about 1/2 hour there, I climbed up to 11.5K
ft. for radar coverage, and within a minute my SpO2 levels were down to
78%. I did NOT put O2 on, but monitored my levels, which stayed at 78%.
I was yawning a bit, and deep breathing could raise the levels for a
short period, but when I went back to regular breathing, it would drop
back to 78%. After about 15 minutes at that level, I was cleared to
descend into LAS, and by the time I got down to about 6K ft, my SpO2
levels were back in the low 90's.

It seems clear that it takes very little time for the SpO2 levels to
change and stabilize when climbing and/or descending - a minute or so at
the most, at least for me.

On the way back, I set up the O2 system for both my wife and myself (she
gets headaches at 9K - 10K ft and above, it seems) and we headed out.
At 10.5K ft going west, with the O2 set to one liter/min for both of us,
our SpO2 levels were in the mid 90's - 96% for my wife, and 95% for me.
Personally, I didn't _feel_ much different, although I was definitely
yawning a lot less. I do know that I'm a lot less fatigued after O2
use.

It seems that _I_ should use O2 anytime above 10.5K ft, no matter what
the regs say - for my wife, it's about 9.5K ft for comfort reasons. It
also seems clear that there's no "reservoir" of O2 that's used up as you
climb - your SpO2 levels are dependent upon altitude, and not really on
the time at that altitude - a minute isn't very long.

--
Marc J. Zeitlin
http://www.cozybuilders.org/
Copyright (c) 2005