The carbon dioxide (CO2) blood test measures the level of carbon dioxide in the bloodstream. Carbon dioxide is a waste product produced by the body's metabolism, and it is carried in the blood to the lungs where it is exhaled. The CO2 blood test is part of a group of tests called electrolyte panel or basic metabolic panel. It provides valuable information about the body's acid-base balance and respiratory function. The test measures the amount of carbon dioxide dissolved in the blood, which helps evaluate the body's ability to maintain proper pH levels. Abnormal CO2 levels can indicate various medical conditions.