End-expiratory carbon dioxide refers to the monitoring of end-expiratory carbon dioxide concentration or partial pressure, which can reflect the ventilation function of the lungs, and the presence of some significant abnormalities of pulmonary blood flow can be monitored. In clinical practice, it is mainly used in the application of anesthesia and ventilator safety, as a guide for data. In addition, it can also monitor respiratory insufficiency caused by various reasons, and perform cardiopulmonary resuscitation monitoring for some patients. In case of severe shock, heart failure and pulmonary infarction, and in some specific cases, tracheal intubation under general anesthesia is required. It is also used as a reference to relieve the patient’s vital signs and to provide an indication of the efficacy of the treatment.