Hypoxia: Altitude vs Displacement

[russ_watters]

TL;DR Summary

Is there a difference between high altitude hypoxia and oxygen displacement hypoxia?

I work in HVAC, for those who don't know, and one of the things that you need to protect against in labs and chiller rooms is the risk of asphyxiation due to oxygen displacement by an inert gas. This is often described as analogous to high altitude hypoxia - and the math is related - but is it actually physiologically identical? Or to ask another way, is partial pressure the only thing that matters or does concentration matter?

 

[.Scott]

The physiology is the same - but partial pressure is not the only thing that matters.
You are both exhaling CO2 and inhaling O2. From what I recall from a physiological training seminar, with high altitude hypoxia, part of the problem is that there may not be enough total pressure to overcome the outgoing flow of CO2. So you can get a CO2 block at the alvioli level.