Contraindications to mask oxygenation: 1. Oxygen inhalation is beneficial to people with respiratory dysfunction and can correct hypoxia. 2. Excessive oxygen inhalation will increase the oxygen concentration of the inhaled air, which may lead to oxygen toxicity. 3. Increased alveolar size is not conducive to oxygen inhalation. 4. Facial congestion should not be inhaled. 5. Oxygen inhalation should not be done just after strenuous exercise. 6. Oxygen inhalation by mask is a method of transferring the oxygen needed for breathing from the storage tank to the human lungs. There are mainly medical oxygen masks, aviation oxygen masks and oxygen masks used by air travelers, which play an important role in the treatment of diseases, and the method and flow rate of oxygen inhalation are related to the patient’s condition. High-flow oxygen intake is defined as an inhaled oxygen concentration of more than 40%, which is common in acute lung injury and severe pneumonia, and is applicable to type I respiratory failure, and requires systematic monitoring in the context of treatment. If there is a decrease in systolic blood pressure and a decrease in pulse pressure, it means that oxygen therapy is not working, and arterial blood gas analysis is a more accurate test.