O2-Hb dissociation curve High Altitude (FA13-548)

[83462]

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If at high altitude you have increased ventilation (so you are releaseing more CO2), why would you have a right shift on the curve? Isn't a decrease in CO2 associated with a left shift?

FA 2013 - pg. 548

 

[Zzmed]

If at high altitude you have increased ventilation (so you are releaseing more CO2), why would you have a right shift on the curve? Isn't a decrease in CO2 associated with a left shift?

FA 2013 - pg. 548

At high altitute you have a decrease in PO2 (hypoxemia) and a chronic increase in ventilation (and respiratory alkalosis) to compensate for the decreased O2 in your blood.
So, you get your erythropoietin up (to increase the O2 carrying capacity of your blood) and you get your 2,3 BPG up (bind to hemoglobin, so it forces it to release O2--> more oxygen in the blood). The latter causes s right-shift on the curve.

Now, as you correctly said, decreased CO2 levels in the blood could cause a left shift on thr curve. This does not happen obviously because 1. could worsen your problem 2. the 2,3 BPG effect is greater.

 

[SLC]

If at high altitude you have increased ventilation (so you are releaseing more CO2), why would you have a right shift on the curve? Isn't a decrease in CO2 associated with a left shift?

FA 2013 - pg. 548

Increase in 2,6 BPG at high altitudes. Less O2 binding, but better O2 releasing.

It's counterintuitive, but that's how it works.

Edit: Zzmed beat me to it...

 

[83462]

Sweet. Thanks for the answer!

 

[MedicalBeast]

the way i understood it is that right when you are exposed to high altitude the initial reaction will be a left shift as you hyperventillate, then followed by right shift as your body compensates by increasing bpg. so overall there is a right shift.