High level of carbon dioxide in the blood results in hypercapnia and low level of carbon dioxide is called hypocapnia. There are several tests to test the level of carbon dioxide in the blood serum. Blood serum is the liquid part of blood. CO2 is present in two forms in the blood which are HCO3 which is bicarbonate, the main form of CO2 in the body, it is also the official name of total CO2 and PCO2. There can be signs of imbalance of oxygen and CO2 or a pH imbalance these signs point to dysfunction involving the exchange between O2 and CO2. This can be due to shallow breathing because of which the CO2 is not exhaled properly or when the production of CO2 is too high to be completely exchanged in the lungs or rebreathing exhaled air due to poor ventilation results in acute hypercania. The symptoms include a sign shortness of breath, sweating, anxiety, nausea, weakness, fatigue and vomiting.