Dyspnea feels out of breath, may be respiratory system, heart disease, but also may be psychosomatic factors, specific introduction is as follows: 1. Respiratory diseases: the more common is to cause expiratory dyspnea disease, such as chronic obstructive pulmonary disease and bronchial asthma; foreign body inhalation trachea and bronchial tubes can also lead to dyspnea, this is a more dangerous situation, especially infants and young children, we must first rule out the inhalation of foreign bodies, otherwise it will lead to a life-threatening situation. 2. Heart disease: when the blood supply to the heart is insufficient, there will be chest tightness, shortness of breath, and the symptom of not being able to feel the air, the more common is coronary heart disease, in addition, myocarditis may also have this symptom. 3. Psychological factors: if emotional tension, or in the case of anxiety, can also appear this phenomenon of dyspnea. Dyspnea may also be due to other reasons, you should go to the hospital in time to improve the relevant examination to clarify the diagnosis, timely treatment, avoid delay.