On 26 Jan 2007 09:09:22 -0800, "Udo" wrote:

Are there any factors, other then altitude it self,
that can lower Blood oxygen level during flight assuming supplemental
oxygen is not used between 5000 and 10000 ft and the pilot has a normal
cardio vascular health? What oxygen level is considered optimum at sea
level and 10000ft to 15000ft?
Udo

other factors.....

obesity has an adverse effect. you will see the effects of hypoxia
appearing at a lower level. cabin altitude of around 8,000ft in
commercial airliners is at the level above which obese people will
start showing effects. a lean lerson will probably have the onset of
effects around 12,000ft.

cigarette smoking loads up the system with carbon monoxide which
reacts out some of the haemoglobin and reduces the oxygen transport
capacity of the blood. this can give a smoker an apparent 5000ft
increase in altitude over a non smoker. carbon monoxide in a glider
shouldnt be a risk.

optimum blood oxygenation would be above 98% at any altitude.

it is a complex issue. the oxygen transport ability of the blood is
not a straight line graph and it varies with blood pH. (Co2 levels)

what is important is that your oxygen system maintains oxygen at an
adequate partial pressure. simply supplying oxygen is only part of the
picture. you must supply it at sufficient partial pressure to overcome
the resistence to permeation in the lung tissue.
I havent the figures to hand but over a ceratin altitude a nasal
canula wont work and you need a full pressure mask. I think it is
nominally about 18,000ft

the simplest path out of the mess is to use a functioning finger clip
laser pulse/oxymeter. consider a blood oxygen level below 92 as
something warranting action and make sure you have working batteries.

dont hold your breath....
Stealth Pilot