I think gbold has opened up some lines of inquiry that will be helpful.
From my understanding, doctors measure pCO2 and bicarb, and this buffer system, while not that significant a buffer system, also measures other buffer systems like serum protein and the calcium in your bones because your body will balance all these buffer systems together.
One claim Peat has made is that a higher amount of breathed in Co2, such as on a submarine, means less excreted Calcium and stronger bones. Although Peat also accounts for oxygen pressure being important...this is why being at high elevation is different then just sucking on a brown bag all day at low elevation...from my understanding.
What gbold is basically saying is that the higher Co2 in venous blood is forcing the body to lower energy production. Peat claims the higher amount of Co2 increases metabolic rate...but I am not sure Peat claims that higher venous Co2 is that same as living at a higher elevation. Peat also uses Co2 baths and these have a nice track record of making people feel great. I have actually experienced both of the cases described by Peat and by gbold. I just got back from a camping trip at 8k feet, and had a much stronger metabolism, better sleep, more energy, etc. I have also sat at home, breathed in a paper bag, and felt tired, uninspired, and low metabolic rate.
High altitude causes low CO2 since it causes hyperventilation and respiratory alkalosis, this is a known FACT. I have no idea what Peat talks about
High altitude causes you to breathe faster looking for oxygen. This makes you breath out CO2 and this forces the body to make more CO2 in the cell.
Respiratory alkalosis - Wikipedia Read and see the causes of respiratory alkalosis( low CO2)