Breathlessness and the desire to take deep breaths are mainly due to insufficient oxygen. If it is on 6 km altitude, normal people can also be out of breath and always want to take a deep breath. If in normal latitude, normal living environment, such as running 800 meters will also be out of breath, running five floors will also be out of breath. If there is no cause mentioned above, the causes of dyspnea are mainly respiratory system and circulatory system problems, as follows: 1. Respiratory system: usually airway obstruction or lung disease, such as pneumonia, pleural effusion; 2. Nervous system: if there is a lesion, the patient can also be unable to breathe; 3. Circulatory system: such as heart failure, hypertension, pulmonary embolism, pulmonary hypertension can also lead to dyspnea; 4. Other aspects: A few patients are caused by poisoning and blood diseases; patients with neuropsychiatric diseases may feel tightness in the chest and tightness in the air, and its a psychological factor. Patients with chest tightness and tightness of breath should find cardiovascular and respiratory doctors for differential diagnosis.