A redefinition of normal acid-base equilibrium in man: carbon dioxide tension as a key determinant of normal plasma bicarbonate concentration

Kidney Int. 1979 Nov;16(5):612-8. doi: 10.1038/ki.1979.171.


It has been shown recently that normal acid-base equilibrium in the dog is characterized by a strong positive correlation between plasma bicarbonate concentration and PCO2. The present study was undertaken to examine the possibility that a similar relationship between normal levels of PCO2 and plasma bicarbonate might be present in man. The results indicate that values for bicarbonate within the normal range are highly dependent upon the prevailing level of PCO2 ([HCO3-] = 0.36 PaVCO2 + 10.4; r = 0.73). Thus, approximately 50% of the normal variance in bicarbonate concentration is explained simply by the variance in PCO2. The joint confidence region for bicarbonate concentration and PCO2, that can be derived from these data provides a new and more rigorous definition of normal acid-base equilibrium in man.

Publication types

  • Comparative Study

MeSH terms

  • Acid-Base Equilibrium*
  • Animals
  • Bicarbonates / blood*
  • Carbon Dioxide / blood*
  • Dogs
  • Humans
  • Hydrogen-Ion Concentration
  • Models, Biological
  • Probability


  • Bicarbonates
  • Carbon Dioxide