Can’t get out of breath chest tightness is relatively common in clinical practice, mainly due to the following reasons: 1, heart reasons. The most common is left heart failure caused by pulmonary stasis, resulting in thickening of the respiratory membrane, affecting the blood in the lungs for gas exchange, so that the whole body is in a state of hypoxia, thus feeling chest tightness. 2, the lungs of the reasons, the most common is bronchial asthma attack, this disease will cause spasm of the smooth muscle of the airway, inhalation of gas is easy, and exhalation of gas is difficult, at the same time, the mucus secreted by the trachea increases, all of which affects the lungs The gas exchange, resulting in hypoxemia caused by chest tightness. 3, mental and psychological factors, the patient is often accompanied by tension, anxiety, usually sleep deprivation, lack of exercise, the symptoms tend to appear in the quiet rest, routine cardiopulmonary examination are normal, to encourage patients to exercise more, to improve their living habits, and when necessary, see a psychiatrist.