On Thursday, September 26, 2013 11:49:23 PM UTC-4, Eric Greenwell wrote:
Since I can keep O2 saturation above 95% at even 18000' using the normal
EDS settings, does that mean I have excellent circulation? Or really
good lung function?


It could also mean that you breathing too rapidly or deeply (mild hyperventilating). Hyperventilation will dilate your finger blood vessels and RAISE the pulse oximeter saturation number. And hyperventilation will simultaneously constrict your cerebral blood vessels, and thereby LOWER the O2 saturation of the blood going to your brain (thereby inducing mild hypoxia). Vasodilation may also lower the temperature of your core and induce the mental dulling effects of mild hypothermia.

See http://www.danlj.org/~danlj/Soaring/...-p18-20-22.pdf

It does drop into the 90-95% range sometimes, but that's also when I
realize my breathing is very shallow; i.e., I don't seem to be inhaling
very much after I hear the "poosh" of the EDS oxygen pulse.

If you're making any conscious effort to "breath", you may be mildly hyperventilating.

A common way to breath at the correct rate is to talk (or sing) out loud, this distracts you from thinking about your respiration rate. The autonomic nervous system works best without conscious or emotional intervention.