In clinical practice, the indications for ventilator use are as follows: 1. acute hypoxia and carbon dioxide retention due to respiratory arrest or severe hypoventilation of the lungs from various causes, resulting in impaired ventilation. 2. severe abnormal shunts in the lungs, resulting in significant hypoxemia, leading to respiratory failure. 3. some large surgical procedures, including cardiopulmonary and acute abdominal surgery, to prevent respiratory dysfunction after surgery. To prevent respiratory dysfunction after surgery, temporary ventilator assisted support of respiratory function is performed. 4, Severe hyperventilation, resulting in alkalosis, and acidosis caused by respiratory disturbances, resulting in respiratory distress. 5, Respiratory rate is too fast, such as 30 times per minute, and lung volume is low, less than 10 ml per kg of body weight.