Patients with chronic obstructive pulmonary disease should not be given high-flow oxygen, but low-flow oxygen, because the high concentration of inhaled oxygen will cause carbon dioxide retention and aggravate hypoxemia. Because chronic obstructive pulmonary disease develops from chronic bronchitis and is complicated by emphysema, which leads to dysfunction of pulmonary ventilation, the increase in emphysema leads to a large number of alveolar capillaries and a decrease in inter-alveolar blood flow. Finally, it causes poor ventilation of the alveoli, which cannot participate in gas exchange and leads to hypoxia, and the ratio of ventilation to blood flow becomes imbalanced, and the gas exchange function becomes impaired, resulting in carbon dioxide retention and varying degrees of hypoxemia and hypercarbia, leading to respiratory failure. Therefore, the administration of low-flow oxygen can improve hypoxemia without increasing carbon dioxide retention and aggravating the disease.