Is there a risk of hyperviscosity and stroke like in polycythemia vera in people at altitude for extended periods of time?
Acclimatized lowlanders do due to diuresis -> increased hematocrit, but less of an issue for people at altitude for a long time like Sherpas. For stroke, people who climb at altitude are in good shape in general, but with increasing comorbid population going to altitude it may be beneficial to take aspirin or low molecular weight heparin prophylactically
I have taken diamox/acetazolamide for altitude and learned about it in med school as artificially causing the same process as the compensation you mentioned. About how long does this take to work?
The typical instruction is to start a day before ascending to altitude - this offsets the respiratory alkalosis by diuresing. However as an expedition medic, it does have a lot of side effects and may not be the best idea to take if you’ve never been to altitude before and don’t know how you will react
What is the risk of too much oxygen in space?
If you think about being in an EVA it is more like being at a high altitude than at depth like divers. Therefore, they are at a much lower risk than a diver on oxygen to develop oxygen toxicity.
Could you restate the mechanism of injury for the hypothermic climber?
The skier fell into a crevice and the friends who were there with her were not able to get her out with ropes. The cold flowing water caused hypothermia relatively quickly which led to enzymes denaturing (like sodium-potassium ATPase) and likely led to hyperkalemic cardiac arrest. There was no significant trauma from the fall that could have contributed to the cardiac arrest (the fact that she was able to move for the first 30ish mins indicates that she was not seriously injured).
Is there any hypothesis as to why some of the subjects had different/opposite physiological reactions?
We still don’t know, but there is current research looking into different hypotheses that could explain this difference.