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Esat,
The values I transcribed from Dr. Buhlmann's text are for inspired O2
and N2 partial pressure. He calculates them from:

	PIO2 = FIO2 x (P - 0.063)
	PIN2 = FIN2 x (P - 0.063)
where:
	PIO2 - Inspired partial pressure of oxygen
	PIN2 - Inspired partial pressure of nitrogen
	P    - Total pressure
	0.063 - Vapor pressure of moisture in the respiratory
		passages at 37 degrees C.

He further continues:

	PAO2 = PIO2 - [(PACO2 - PICO2) x (FIO2 + (1 - FIO2)/R)]

where:	
	PAO2 - Alveolar partial pressure of oxygen
	PACO2 - Alveolar partial pressure of carbon dioxide
	PICO2 - Inspired partial pressure of CO2
	R - Respiratory Quotient = quantity of expired CO2 / absorbed O2

I think many of the posts are looking too deep into this subject of
hypoxia at altitude. It is very clear that hypoxia can occur at a
sufficient altitude on air, or Nitrox for that matter. However when
the diver descends from the surface, the O2 partial pressure will
increase and move out of the hypoxic range. When the diver returns 
to the surface he or she may again enter the hypoxic range. This is not 
a mystery. 

Some of the posts are suggesting a physiologic phenomenon which occurs 
at altitude due to the higher percentage of O2 in Nitrox which causes a 
hypoxic condition after the dive. If this was true, you would think it 
would also occur at sealevel with Nitrox, and it very well may as there 
are many physiologic processes which occur during dive that are not 
well understood, especially by layman. I certainly don't know. 

Thanks for your comments,
Doug Chapman

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