1.Definition An asthma attack with severe or progressive inspiratory difficulty even after reasonable application of conventional relieving medication is called asthma critical state (asthma persistent state). As the bronchial tubes are severely obstructed and life-threatening at this time, treatment should be actively carried out. 2.Pathophysiology In critical asthma, severe obstruction of airflow in the lower whistle tract increases the closed volume and residual air volume of the lungs, uneven distribution of gas in the lungs, changes in thoracic pressure, increased afterload on the left and right ventricles, and interstitial edema in the lungs, eventually leading to an imbalance in the ventilation/perfusion ratio, impaired gas exchange, hypoxemia and metabolic acidosis. Severe cases can be combined with whistling acidosis, whistling muscle fatigue, and even death. 3, clinical manifestations of acute asthma attacks, coughing, wheezing, dyspnea, sweating and restlessness, or even show signs of sitting whistling, incoherent speech, severe cyanosis, impaired consciousness and cardiopulmonary insufficiency. If the lung auscultation whistling sound is distant or inaudible croup, it indicates serious airway obstruction, which can be life-threatening immediately and should be immediately resuscitated. Blood gas analysis: early manifestation of critical asthma is hypoxemia and hypocarbia due to compensatory hyperventilation, if the condition further deteriorates, the trend of increased PCO2 indicates serious airway obstruction and the child is in critical condition. Ventilation: Most children have a PEFR < 50% of the expected value, if the PEFR is < 33% of the expected The trend of increasing airway obstruction is indicative of severe airway obstruction. Any critically ill child with asthma should be actively resuscitated in a good medical environment, with cardiopulmonary monitoring, blood gas analysis and ventilation monitoring, and sedation should be used with caution for those who are not extubated.