CO in the medical field can have several meanings: 1, the abbreviation of carbon monoxide, a toxic substance, people in the inhalation of carbon monoxide will be closely bound to the hemoglobin, strong accounting for the binding point of oxygen and hemoglobin, the binding force is much higher than oxygen, which leads to human hypoxia, respiratory failure, and even death in serious cases, carbon monoxide poisoning can show cherry red lips, the usual gas poisoning that is because of CO The cardiac output can be used to evaluate and respond to the function of the heart, and the cardiac output is affected by the metabolism and activities of the body, and increases in the case of muscle movement and emotional excitement. 3, it can indicate chemical elements such as cobalt, and excessive intake of cobalt can easily lead to allergic asthma and allergic dermatitis.