minimum O2 Saturation

[maehhh]

I got myself a O2-Pulse-Oxymeter and spent some time at FL095 last week.... My O2-saturation was oscillating between 90 - 94 % all the time (at 99bpm).

Now I have got the numbers but I am not really sure how to deal with them... ? What is a sensible minimum to avoid Hypoxia?

regards
maehhh

[Mark 1]

If you drop below 90%, I think it is a good idea to turn on the oxygen or lose some altitude. You may want to consider higher than that at night.

Even at 90% it can freshen you up considerably having a few minutes "on the bottle". I'd certainly use it before descending into busy airspace at the end of a flight, if I'd got it with me.

[Dg800]

Below 96% you are technically hypoxic. Hospital patients are automatically given supplemental oxygen if their blood oxygenation level drops below that. Of course you won't immediately pass out at 94%, but fatigue will become more of an issue the longer you are exposed to these levels. Alertness will decrease with time and you might exhibit symptoms such as lingering headaches and reduced field of vision.
90% is on the other hand already pretty low, depending on whether you're a smoker and your age and fitness level you might already be in danger of becoming severely hypoxic, something you definitely want to avoid. :}
I'd definitely hit the oxygen if I were you, if only to avoid the lingering headache that might keep bothering you long after you've reached your destination.
Cheers,

Dg800

[IO540]

90-94% is fine, generally.

There are various views on this, and there is a lot of variation within the medical profession also, but in general you want to keep your oxygen level no lower than 10 percentage points below your sea level figure (which for most non smokers is about 98-99%).

One can tolerate lower levels for short periods; for example 85% might be OK for half an hour but most people will arrive well knackered after such a flight lasting 5 hours. This is why I use o2 anytime above FL090, and try to keep it above 94% all the time (not easy with a cannula at FL180 :) ). Many Eurocontrol IFR routings are poor below FL120/130 anyway.

Your brain doesn't stop working at say 85%. It is a gradual thing.

There is a large subsection of the IFR community which flies without oxygen, works hard to find routings at/below FL100, and wonders why they are so tired after every trip.

What kind of oxygen system are you using?

Some notes on oxygen systems are here (http://www.peter2000.co.uk/aviation/oxygen/index.html).

[Dg800]

Incidentally, 90% seems a bit lowish for FL095. If you're a healthy, young, non smoking person and still feel great at 90% measured saturation, I'd also check the oxymeter for accuracy, especially if it's one of the very cheap ones!

Ciao,

Dg800

[S-Works]

You are not hypoxic below 96% and lets not confuse medical treatment with normality.

I would expect as a norm to see around 87-90% sat at FL100 for a healthy adult. When you are new to being at altitude and not aclimatised this can lead to feelings opf fatigue and in some not being the sharpest knife in the box.

If you use supplemental oxygen delivered by canula you can expect to improve this to between 95-97%.

A smoker will experience slightly lower levels of O2 as Heamoglobin bonds with CO 25 times more readily than O2 and as such it is more difficult for the O2 to transfer. If you must smoke and fly without O2 try and refrain from doing so for a few hours prior to the flight as it will aid your body in eliminating the CO and make best use of the available O2.

Regular exposure to altitude helps our bodies become acclimatised and transfer the o2 more readily. Its the reason why people who live on the side of a mountain have no problems.

[IO540]

Incidentally, 90% seems a bit lowish for FL095. If you're a healthy, young, non smoking person and still feel great at 90% measured saturation, I'd also check the oxymeter for accuracy, especially if it's one of the very cheap ones!

I haven't tested this myself but 90% at FL095 doesn't seem particularly wrong.

[BackPacker]

If you must smoke and fly without O2 try and refrain from doing so for a few hours prior to the flight as it will aid your body in eliminating the CO

I always thought that the bond between Hb and CO was so strong that the CO was, in effect, never released again from the Hb molecule, rendering that molecule effectively useless for oxygen transport. Until the Hb molecule is regenerated in the body - something that happens, on average, every three months. That's why it may take victims of CO poisoning up to three months to recover fully.

So by what mechanism does smoking inhibit oxygen transport, in addition to the above? And does that effect really wear off in a few hours?

I'm not a smoker (and don't intend to become one) but I'd think that if you're addicted to smoking it's better to have a smoke just beforehand and do the flight reasonably relaxed, than not having a smoke just beforehand and suffer from withdrawal effects the whole flight.

Edited: Just read the Wikipedia article and it seems the half-life of HbCO is about 320 minutes instead of the three months I believed it was. So yes, this advice makes perfect sense to me now.

Carbon monoxide poisoning - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Carbon_monoxide_poisoning)