A ventilator helps breathing but does not work on lung function. When a patient is on a ventilator, the ventilator helps the patient to breathe. Simply put, when the patient is using a ventilator, breathing will be easier, because when the ventilator ventilates autonomously, the inspiratory action generates negative pressure in the chest cavity, and the lungs passively expand to appear negative pressure in the alveoli and airways, which constitutes a pressure difference between the airway opening and the alveoli to complete inhalation; after inhalation, the thorax and lungs elastically retract to generate the opposite pressure difference to complete exhalation. The action of breathing can be done by the respiratory muscles actively, and the patient’s diaphragm can be rested. This will make breathing easier. Ventilators play the role of “artificial lungs” and can only be used in cases of respiratory failure, sleep apnea, pulmonary embolism, acute respiratory distress syndrome, pulmonary fibrosis and other diseases that cause respiratory distress. But it does not exercise lung function. Exercise lung function can be through aerobic exercise such as jogging, running, swimming, etc., but also through abdominal breathing exercise diaphragm function, so as to improve lung function. Resistance training with the application of respiratory trainer can improve lung function. When abnormal lung function occurs, it is recommended to consult a doctor in time to find out the cause, clarify the cause with the help of the doctor, and carry out targeted treatment or therapy.