What's minimum safe O2 level?

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

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
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the blog www.danford.net

Cub Driver wrote in message . ..
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!


One of my instructors was of the opinion (and I susbscribe to it) that
as PIC oxygen at night above 10,000 feet and 12,000 during the day. No
exceptions.