Carbon dioxide retention is mainly a clinical condition in which the blood in the body contains too much carbon dioxide, which easily causes hypercapnia, even accompanied by hypoxemia, which easily causes hypoxia in the body and causes respiratory distress and respiratory failure. First of all, to relieve the hypoxic state, according to the different etiology choose different ways to treat, need to carry out oxygen, for example, for chronic bronchitis, chronic obstructive pulmonary disease, can choose continuous low flow, low concentration of oxygen, oxygen concentration can be controlled within 30%, oxygen flow rate can be controlled at 1-2L/min. If it is carbon monoxide poisoning or serious lung infection, fibrosis, etc. caused by In case of acute hypoxia or respiratory distress syndrome caused by carbon monoxide poisoning or severe lung infection or fibrosis, end-expiratory positive pressure ventilation can be chosen if necessary, with oxygen concentration of 40%-60% and oxygen flow rate of 4-7 L/min. This can continuously expel carbon dioxide from the body, relieve the state of hypoxia in the body and prevent the emergence of respiratory failure, which is life-threatening.