Asthma patients will die suddenly when the attack period is serious, divided into two cases, as follows: 1, asthma patients are suddenly exposed to strong allergens, such allergens can lead to violent spasms in the airway and even in the larynx of the large airway, patients suddenly show dyspnea, obstructed breathing, severe breath-holding, rapid cyanosis, lack of oxygen, while sweating profusely, panic, at this time there is no sound in the lungs, because the airway is occluded, airflow can not go in and out, so there is no breath sound on the lungs on auscultation, the croup disappears, clinically called resting lung, and the patient will die in a short time due to suffocation during a lethal asthma attack; 2. Asthma patients have underlying diseases, such as coronary artery disease, usual coronary stenosis, myocardial ischemia and hypoxia, when an asthma attack, although the degree of asthma is not lethal, but induces heart complications, rapid arrhythmia or even induces heart failure, etc., when It can also lead to death of the patient due to asthma attack.