The following reasons are common for low carbon dioxide values in blood gas analysis: 1) Fever, which can cause faster metabolism and faster breathing, which can exhale more carbon dioxide. 2) Exercise, which can also cause faster breathing and low carbon dioxide values. 3) Lung diseases and thoracic diseases, which can cause faster breathing or faster breathing due to lack of oxygen, which can exhale more carbon dioxide and cause low carbon dioxide. 4.Emotional agitation can cause faster breathing and excessive carbon dioxide emission. If you find that the carbon dioxide value is often low, except for the common causes such as exercise, fever, emotional excitement, etc., you should also exclude whether the patient has lung problems, and if necessary, further examination should be conducted to clarify the cause.