Whether food can be expelled when it enters the trachea is determined by the size and shape of the food, the amount of food, the depth of the entry location, the specific site of entry, and the person’s physical condition. A small amount of liquid food, for example, less than 5 mg, enters at a relatively shallow location, and most people can immediately cough up the liquid food through the cough reflex. If the entry location is deeper, such as having entered below the segmental bronchus, it may be gradually absorbed by the body and cannot be expelled. If the food is hard, such as bones or fish spines, most people cannot expel it if it enters deeper, and it will repeatedly produce irritating chronic inflammation in the bronchus. If the food is large, only a part of it can be expelled. If a person is in poor health, such as a patient who is bedridden for a long time, or a patient with sequelae of cerebral infarction, the coughing power is limited, and it is difficult to expel the food after it enters the trachea, and it is necessary to use external auxiliary power, such as aspiration or bronchoscopic flushing, before it can be completely expelled.