Oxygen 90, fast heart rate may be due to heart failure, chronic obstructive pulmonary disease, bronchial asthma, etc., need to cause, symptomatic treatment, follow the doctor’s instructions to take medication, mechanical ventilation therapy, nutritional support therapy. 1. Heart failure: when the ventricular filling or ejection function is impaired due to various causes, and the cardiac output is lowered, the blood perfusion is insufficient, the blood oxygen saturation will be decreased, and the heart rate will be accelerated compensatorily. Patients need to find out the cause of heart failure in time, combined with medical history, under the guidance of the doctor to take anti-heart failure drugs, such as furosemide, aminophylline, sodium nitroprusside, nitroglycerin and so on. 2. Acute exacerbation of chronic obstructive pulmonary disease (COPD): commonly seen in elderly long-term smokers, the onset of oxygen saturation decreased, heart rate accelerated. Cough, sputum, shortness of breath and other symptoms can also occur. Acute onset of patients need to consult a doctor in a timely manner, given amoxicillin, clindamycin, levofloxacin and other drugs anti-infective and oxygen therapy. 3. Bronchial asthma: often after contact with pollen and other allergens, sudden dyspnea, rapid heart rate, oxygen saturation decreased. Patients need to seek prompt medical attention and be given terbutaline, salbutamol, glucocorticoid therapy. Oxygen saturation of 90% and rapid heart rate require prompt medical attention. When the condition improves, identify the cause of the disease and actively treat the primary disease. Daily away from harmful factors, strengthen exercise, patients need to quit smoking, appropriate exercise, reasonable diet, away from irritating gases and environmental dust.