Carboxyhemoglobin NCIT:C114300 SCDO:1000168 Hemoglobin where the heme group has formed a stable complex with carbon monoxide (CO). This complex is produced after CO has been inhaled or as a byproduct of hemoglobin, protoporphyrin or dichloromethane catabolism. The heme-CO complex is approximately 200 times more stable than heme-oxygen complexes. Thus, high levels of carboxyhemoglobin in the circulation can lead to tissue hypoxia and death. Sufficient COHb Hemoglobin