Total CO2 content:
Consists of hco3-, h2co3, and dissolved co2 (pco2). (since co2 and h2co3 are interchangable) total co2 = dissolved co2 gas + hco3-. Or total co2 = hco3- + (0.03 * pco2). (the co2 solubility coefficient, 0.03, converts pco2 in mm/l to meq/l) in normal plasma, more than 95% of the total co2 is contributed by hco3-, the other 5% by dissolved co2 and h2co3.