What's minimum safe O2 level?

Well, what's about all the "high-landers" who often live at ore above
8K? ;-) (I live above 7K year round for example)
I would guess that goes with Mike's obervation. One adapts to high
altitudes but it takes a day or two (or three). For short trips up one
may end up hypoxic.
What I still have to find out (in an pressure chamber) where my limits
would be.

Chris
PP-ASEL, Glider
New Mexico

Blanche wrote:
Cub Driver wrote:

On 6 Nov 2004 19:20:43 -0800, (PaulH) wrote:


I took my Arrow up to 10,500 today

I have been skiing at Ajax (Aspen Mountain) on a regular basis for
nearly forty years and have never noticed any effect on mental acuity
at 11,000 feet. Of course it may be that skiers are mentally inacute
to begin with.


But Dan, we *start* at 5K+ MSL! I ski Loveland (10-11K) all the
time with no problems. But remember, we're up and down within
15-30 min (depending on the lift lines and being amazed at where
we live). Flying is something else -- we stay up there for long
periods of time.

My body prefers O2 any time I've over 8K MSL for more than an
hour.

At higher altitudes (Flight Levels) even 100% O2 is not sufficient. It must
be delivered under pressure through a secure O2 mask.

--

Darrell R. Schmidt
B-58 Hustler History: http://members.cox.net/dschmidt1/
-

"PaulH" wrote in message
om...
I took my Arrow up to 10,500 today to check out my fingertip O2
measuring device. I can maintain 90-93% saturation with deep
breathing and no supplemental O2. Anybody know what the minimum safe
level is for daytime? I guess it might be cumulative, i.e. the longer
you go at 92% the less safe it is? Dropped down to about 88% when I
got distracted with some cockpit chores and started normal sea level
breathing.

Cub Driver wrote:

I have been skiing at Ajax (Aspen Mountain) on a regular basis for
nearly forty years and have never noticed any effect on mental acuity
at 11,000 feet.

It is the very nature of hypoxia that you don't recognize it yourself.
Actually, this is the point which makes it so dangerous. I'm somewhat
shocked that a pilot wouldn't know this.

Of course it may be that skiers are mentally inacute
to begin with.

One thing is to walk around (or ski around or climb around, for that
matter). It's a very different thing to work mentally, as is piloting.

Stefan

PaulH wrote:
I took my Arrow up to 10,500 today to check out my fingertip O2
measuring device. I can maintain 90-93% saturation with deep
breathing and no supplemental O2. Anybody know what the minimum safe
level is for daytime? I guess it might be cumulative, i.e. the longer
you go at 92% the less safe it is? Dropped down to about 88% when I
got distracted with some cockpit chores and started normal sea level
breathing.

Once your oxygen saturation gets to about 90% you are at a point where
any further decrease in ambient oxygen pressure can cause a big drop in
the saturation. So, for instance, a decrease in atmospheric pressure
might significantly decrease the amount of oxygen in your blood. For
this reason, people usually talk about a saturation of 90% as the
minimum safe level.

However, for a healthy person at rest, an oxygen saturation in the mid
80s is likely to be adequate for most people to feel okay and think
normally. (That is not to say that it's a good idea while flying to
intentionally let it get that low rather than use supplemental oxygen.)

In contrast, I'm not so comfortable with "deep breathing" to maintain a
higher oxygen saturation. In accomplishing this, you are almost
certainly decreasing the carbon dioxide in your blood, and that can make
you dizzy, lightheaded, anxious, and/or confused.

--
David Rind

"Larry Dighera" wrote in message
...
On Sun, 07 Nov 2004 13:22:54 GMT, "Viperdoc"
wrote in
::

On a recent trip at 10,000 feet I felt bad after around three hours, and
checked my sat, which was in the low 80's.

This happened to me after about 3-1/2 hours at 12,500'; I felt okay,
but was apparently impaired. ...snip...

Wasn't that borderline violation of the FARs 91.211? (30 mins above 12,500
pressure altitude)

.... and if the altimeter setting for more than 30 minutes of the route was
below 29.92, then it WAS violation..., no???

In Canada it would be violation for sure, cause they want Oxygen for the
crew if more that 30 mins above pressure Altitude 10,000.....

"Viperdoc" wrote in message
...
In general for a patient in a hospital we try to keep the O2 sat at or
above
92%, and will give supplemental oxygen if it falls below.

On a recent trip at 10,000 feet I felt bad after around three hours, and
checked my sat, which was in the low 80's. My eight year old son
complained
of a headache and nausea, and after putting on the oxygen we both felt a
lot
better as our sats returned to the 90's.

A couple years ago, my family went to Quito. The elevation there is around
2 miles high. I am not a great physical specimen, and did not have any
problems with feeling bad. You did have to remember not to make too long of
a sentence without breathing, and to walk instead of running, like up
stairs.

One thing was interesting, was that as we were about to land, the airliner
cabin's altitude went up, instead of down!

Ever seen Quito's airport? It is literally in the middle of the city, with
apartment buildings and such right up to the fence, and the fence is close
to the runway. One runway, because it is in a narrow valley. Arrivals and
departures are not straight in, and have to curve about in the valley as
they descend or climb. Not for the faint of heart. We heard you had to be
a captain for the airline on different routes for 5 years, then fly as 1st
officer on the Quito run for 2 years before you are allowed to command a
flight in there. With good reason.
--
Jim in NC


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On Sun, 7 Nov 2004 17:58:17 -0500, "Icebound"
wrote:

Wasn't that borderline violation of the FARs 91.211? (30 mins above 12,500
pressure altitude)

What is a "borderline violation"?

Is the same as almost but not quite contrary to the regulations? If so,
then you've answered your question.

... and if the altimeter setting for more than 30 minutes of the route was
below 29.92, then it WAS violation..., no???


The regulation is pretty clear in stating that the relevant altitude is
"pressure" altitude.

In Canada it would be violation for sure, cause they want Oxygen for the
crew if more that 30 mins above pressure Altitude 10,000.....



Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)

On Sun, 07 Nov 2004 06:54:42 -0500, Ron Rosenfeld
wrote:

until they were returned to sea level pressure and could view
what they had written.

Of course, returning to standard pressure at Aspen means 8,000 feet.
Perhaps we are off the wall the whole time?

Still, I've never had a waiter complain that I was miscalculating the
tip. Perhaps I've been overtipping? It seems unlikely: my wife has
never complained.

Seriously, 11,000 feet is not a problem unless you have medical
problems. People get altitude *sickness* while skiing at high
altitudes; they might be insomniac; they get dehydrated, especially if
they booze it up; and sometimes they hyperventilate. (One of the ski
patrol tricks with ailing turkeys is to have them breath into a paper
bag, to *cut down* on their oxygen intake.)

Loveland Pass, west of Denver, was higher than 10,000 feet, and
carried all traffic before the I-70 tunnel was built.


all the best -- Dan Ford
email: (put Cubdriver in subject line)

Warbird's Forum www.warbirdforum.com
Piper Cub Forum www.pipercubforum.com
the blog www.danford.net

In contrast, I'm not so comfortable with "deep breathing" to maintain a
higher oxygen saturation. In accomplishing this, you are almost
certainly decreasing the carbon dioxide in your blood, and that can make
you dizzy, lightheaded, anxious, and/or confused.

Thanks. That's a good description of what happens to tourist skiers
when they begin to hyperventilate at high altitudes.

(It was my impression though that they got there by panting rather
than by taking deep, measured breaths.)

I am off to Aspen next month. I'm going to try to forget this thread.
It's not good to be self-concious about one's breathing!


all the best -- Dan Ford
email: (put Cubdriver in subject line)

Warbird's Forum www.warbirdforum.com
Piper Cub Forum www.pipercubforum.com
the blog www.danford.net

Cub Driver wrote:

they booze it up; and sometimes they hyperventilate. (One of the ski
patrol tricks with ailing turkeys is to have them breath into a paper
bag, to *cut down* on their oxygen intake.)

Wrong again. The idea of this trick is to keep the CO2 level up.

Stefan