On 8/5/05, Ernest Christley <echristley@nc.rr.com> wrote:
John Slade wrote:
> I will want one suitable for two users. My back seater won't go over
> 10,500 without it.
>
> Tracy.
> Glad you survived that one. We'd miss you for all sorts of reasons :)
> Take a look at http://www.aeromedix.com
> I got their 2 place system for around $400 complete with a full 640 ox
> bottle. It's gone up a bit since. Haven't had a chance to use it yet,
> but the quality and service seem good.
> Regards,
> John
>
I've bookmarked this page. Very interesting stuff. I'm basically
healthy, and don't plan on much FL flying. But I think one of their
miniature, $289 systems would be useful for the type of situation Tracy
found himself in. If I had that and the Nonin Flightstat, it would
minimize the weight I carry around but still maximize safety. $600 for
a complete oxygen system isn't all that bad.
David, this is probably a good question for you. Would it be necessary
to carry one of the oxygen monitors all the time, or would it be enough
for someone to wear one for a few flights to characterize how their body
reacts and then just use oxygen in those conditions? In other words,
can a person expect to react the same everytime, or is it unpredictable?
Difficult question. In general over the short term you will react pretty much the same as long as nothing else changes. Also, it is not so much your O2 saturation that matters as your ability to tolerate lower saturations. For example, some mountain climbers can function in strenuous environments with SpO2 in the low 30's!!! Others will begin to notice significant effects in the low 90's. Some people live in the low 80's at sea level.
With age, in general, tolerance declines while the amount your saturation drops increases. Many things affect your tolerance such as smoking or other carbon monoxide exposure, lung disease, dehydration, anemia, cerebral vascular disease, heart disease, change in activity level or even a hang over.
So really, the SpO2 monitor tells you very little. It will drop more or less predictably with altitude, but there is no way to say what number is a safe decline.
As expected, the FAA regulations are set for a reasonable lowest common denominator. That means that a few people will experience significant effects even while following the letter of the law, while most can tolerate significantly higher altitudes.
A few years ago I spent about 10 min at 27,000' in an altitude chamber. I was somewhat dizzy, but could communicate and do math. My O2 sat was in the low 70's and dropping. Longer exposure might change things somewhat. Probably couldn't do that now. I notice very little effects at 23k (in a chamber) except for loss of color vision and slight uncoordination - I certainly would have the where-with-all to fly en-route stuff for short periods.
What is hard for me to remember is that I am getting older, as I am in denial. Either way, the important thing is to be able to recognize the subtle effects and say "that's enough," above 14.5k or not.
If you get the opportunity, a chamber ride is an excellent experience. A few people, even those young and in great shape, do react very strangely - and it can vary day to day.
Also, having O2 readily available even if not continuously used would be an excellent and cost effective safety measure for those fly at altitudes where there is the possibility of an issue.
--
Dave Leonard
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