Sudden difficulty in breathing in the trachea during the day.

Dyspnea is an important symptom of respiratory insufficiency, and it is the patient's subjective feeling of insufficient air or strenuous breathing. Objectively, it shows the changes of breathing frequency, depth and rhythm.

According to the main pathogenesis, dyspnea can be divided into the following five types:

1. Pulmonary dyspnea: caused by pathological changes of respiratory organs, mainly manifested in the following three forms:

1) inspiratory dyspnea: manifested as wheezing when inhaling, depression of sternum, supraclavicular fossa and intercostal space-three concave signs. Common in laryngotracheal stenosis, such as inflammation, edema, foreign bodies, tumors and so on.

2) Exhale dyspnea: Exhale gas phase with wheezing, which is found in bronchial asthma and obstructive pulmonary disease.

3) Mixed dyspnea: seen in pneumonia, pulmonary fibrosis, massive pleural effusion, pneumothorax, etc.

2. Cardiogenic dyspnea: It is common in cardiogenic pulmonary edema caused by left ventricular dysfunction, and its clinical features are:

1) The patient has a serious history of heart disease.

2) Mixed dyspnea, especially in prone position and at night.

3) Moderate and small wet gong sounds may appear at the bottom of lung, which varies with body position.

4) X-ray examination: abnormal changes of heart shadow; Congestion or pulmonary edema in hilum and its vicinity.

3. Toxic dyspnea: acidosis caused by various reasons can increase carbon dioxide in blood, decrease pH, stimulate peripheral chemoreceptors or directly excite respiratory axis, and increase respiratory ventilation, which is characterized by deep and heavy dyspnea; When morphine, barbiturates and other respiratory inhibitors are poisoned, they can also inhibit the respiratory center and make breathing shallow and slow.

4. Blood-borne dyspnea: Severe anemia can cause shortness of breath due to decreased red blood cells and insufficient blood oxygen, especially after exercise; Dyspnea is caused by ischemia and blood pressure drop during massive hemorrhage or shock, which stimulates the respiratory center.

5. Neuropsychiatric and myopic dyspnea: serious brain diseases such as encephalitis, cerebrovascular accident and brain tumor directly involve the respiratory center, leading to abnormal respiratory rhythm and dyspnea; Myasthenia gravis crisis causes respiratory muscle paralysis, leading to severe dyspnea; In addition, hysteria can also cause dyspnea, which is characterized by obvious frequency and shallow breathing, often accompanied by tetany due to respiratory alkalosis.