In case of acute heart failure, oxygen is recommended for 24 hours around the clock. In chronic heart failure, it is recommended to take oxygen for about 15 hours and keep continuous oxygen at night. 1. Acute heart failure: when the heart contraction and diastolic function decreases in acute heart failure, there will be stagnation in the pulmonary circulation, pulmonary edema, hypoxia, chest tightness, dyspnea, usually high concentration nasal cannula oxygen, oxygen flow rate of 6~8/L, 24 hours around the clock to give oxygen, so as to improve the myocardial ischemia, hypoxia, dyspnea and hypoxia to alleviate the symptoms of dyspnea. 2. Chronic heart failure: due to the phenomenon of insufficient blood supply to the heart tissue organs, often manifested as dyspnea, cyanosis, oxygen can improve the blood supply function of the heart, increase the blood oxygen saturation, chronic heart failure patients have a certain degree of improvement, it is generally recommended that the patients inhale oxygen for about 15 hours, oxygen flow rate of 1~2/L, daytime can be intermittent oxygen inhalation, the night needs to be sustained low-flow oxygen inhalation. In the process of oxygen inhalation, the oxygen flow cannot be adjusted arbitrarily, so as not to cause oxygen toxicity, avoid smoking, stay away from open flames, the specific oxygen inhalation for a few hours need to be determined by the doctor according to the situation.