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I've been thinking about what Joan's said. Please forgive me for
ruminating out loud and bear with me through the simple stuff...
One of the problems associated with high-altitude diving is that the
atmosphere is at a lower pressure than what the tables assume. This
means that the tables are not valid above some given altitude without
applying a correction factor (or using a capillary depth gauge). This is
due not to the differential in air pressure but to mthe percentage change
of pressure.
If you are saturated at altitude, then 33 feet (10 metres) is no longer
one "atmosphere". Some shallower depth is. This is all well and fine
and good for nitrogen. Let's look at Oxygen.
Note that this is in the nature of a "thought experiment." As has been
proven, thought experiments are often spectacularly wrong when presented
with cold, hard, fact. Otherwise bees wouldn't fly.
Hypothesis: Your body, in attempting to maintain homeostasis, acclimates
to a certain partial pressure of O2.
Check: Upon first ascent from sea level to altitude do you feel better,
worse, or the same as after you've spent a couple of days there?
This adaptation, however, does take an appreciable amount of time.
Query: Can the altitude sickness problems be alleviated through
introduction of oxygen-rich breathing gasses?
Yes. This is done often by mountain climbers.
Query: Is the adaptation to richer oxygen mixes symmetric with adaptation
to depleted oxygen mixes?
I don't know.
If the answer is that someone adapts to richer oxygen mixes faster than
to depleted ones, I can see where someone could exhibit mild hypoxic
signs and symptoms after a dive, with those signs and symptoms exagerated
by breathing Nitrox.
Check (in two parts): Under those circumstances, a diver breathing
Nitrox would feel mild signs of Altitude Sickness upon ascent fromm the depths.
Possible that the mild fatigue some people feel can be partly attributed
to altitude sickness.
(second part): People would feel WORSE after a dive with Nitrox.
Anecdotal evidence seems to suggest that this is the opposite of what occurs.
Conclusion: Nitrox will NOT contribute to hypoxic symptoms at altitude
upon ascent from a dive unless there is some other, discontinuous,
influence that is not present at sea level but is present at altitude.
-- Kevin --
kevink@ap*.co*
It is hard to disagree with a pro-survival decision,
It is even harder to engage in prolonged arguments
with someone who consistently makes anti-survival decisions.
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