High-altitude arterial gases question, old nbme

[alternatego]

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50 yo, lives at sea level, gets on a cable car to get to a ski resort located at 10,000 ft above sea level, which labeled point represents the patient 30 min after his arrival at the resort?

I say its D, but answer key says C

 

[ijn]

I think the answer is C as well. He has respiratory alkalosis and it's too soon for the kidney to mount a compensatory response. His bicarbonate would be close to normal (24) within 30 minutes of stepping off the plane. After a week he should have lower serum bicarbonate levels.

 

[thehundredthone]

C is correct. He will not compensate within 30min. If the high HCO3 is throwing you off, remember that even in uncompensated respiratory alkalosis/acidosis, there is some change in HCO3.

 

[alternatego]

thanks guys! it was the blood pH that was throwing me off, I didn't expect such a large increase in pH