Early identification features of severe cases (especially in patients under 3 years of age): 1. Persistent high fever that does not subside. 2.Poor mental health, vomiting, easily startled, shaking limbs, weakness. 3. Increased respiration and heart rate. 4.Cold sweating, poor peripheral circulation. 5.High blood pressure. 6.Significant increase in peripheral blood white blood cell count. 7.High blood sugar. However, for some children with atypical HFMD, especially in the early stage of HFMD epidemic, in addition to the above early recognition signs, we must be highly alert to children with fever, vomiting or fever, shortness of breath (without cough and other respiratory symptoms) as the first symptom, paying special attention to male children within 3 days of onset, and strive for cranial MRI or CT examination if possible to exclude brainstem encephalitis, and the subsequent appearance of pulmonary edema and pulmonary hemorrhage. In case of pulmonary hemorrhage, the success rate of resuscitation is very low. Therefore, children with high suspicion must be kept in the hospital for 4-5 days for observation, to improve the relevant auxiliary examinations and pathogenic examinations, and to perform dynamic chest radiography (once an hour for children with shortness of breath). For such children or EV71-positive infected children with and without rash, although they do not reach the 7 signs of the guidelines, in addition to close observation, effective interventional treatment (such as methylprednisolone, intravenous propecia, mannitol, etc.) can be performed early if necessary, with tracheal intubation and mechanical ventilation prepared, and once shortness of breath, cyanosis, increased heart rate, and dry and wet rales on lung auscultation occur, pulmonary edema or pulmonary hemorrhage may have occurred Tracheal intubation and corresponding first-aid measures should be taken immediately to improve the success rate of resuscitation and reduce mortality.