Carbon dioxide is transported in form of carbamino haemoglobin. When the partial pressure of carbon dioxide is high it combines with the haemoglobin and gets transported as carbamino haemoglobin.
Carbon dioxide is also transported in form of bicarbonate. When the partial pressure of carbon dioxide is high at the tissue site, it diffuses into the blood and forms bicarbonate in the RBC. The enzyme carbonic anhydrase present in the RBC helps in the formation of bicarbonates.