Welcome to Episode 4! We are continuing our discussion on the important serum electrolytes by discussing serum CO2 or serum bicarbonate, they're the same thing! Carbon Dioxide is a measure of bicarbonate in the blood. CO2, as bicarbonate, is available for acid-base balancing. Bicarbonate neutralizes metabolic acids in the body. Elevated levels of CO2 are associated with metabolic alkalosis and hypochlorhydria. Decreased levels are associated with metabolic acidosis.