co2 content co2 content co2 content (also known as "total co2") is a blood test that usually appears on a "chem 19" or an electrolyte panel. the value measures the total dissolved carbon dioxide (co2) in blood. it is determined by combining the bicarbonate (hco−3) and the partial pressure of co2 multiplied by a factor which estimates the amount of pure co2 that is dissolved in its natural form (usually 0.03). one given reference range is 24–32 meq/l.