Blood oxygen is made up by oxygen inhalation. The human transcutaneous pulse oxygen is above 95%, if the transcutaneous pulse oxygen is below 95%, there may be a hypoxic state and oxygen inhalation therapy is needed. Patients with mild hypoxia can be improved by ordinary oxygen therapy. If the hypoxia is more severe, mask oxygen administration may be required, and the oxygen concentration needs to be increased to improve the hypoxic state. If the patient has shortness of breath, dyspnea, rapid heart rate, cyanosis of lips and mouth, transdermal finger pulse oxygen continues to be below 90%, blood gas analysis indicates partial pressure of oxygen is below 60mmHg, oxygenation index is less than 250mmHg, the patient may have respiratory failure. At this time, it is difficult to maintain the patient’s oxygenation and correct the patient’s hypoxic state by simple mask oxygen administration, so tracheal intubation and mechanical ventilation are needed to correct the patient’s respiratory failure and improve the patient’s blood oxygen.