Pulmonary edema is generally more terrible, acute pulmonary edema can appear to appear dyspnea, sitting breathing, sweating and other symptoms, the emergence of difficult to correct hypoxemia, pulmonary atelectasis, causing respiratory and circulatory failure and life-threatening. 1. Pulmonary edema can cause chest tightness, cyanosis, dyspnea, sitting breathing, sweating, near-death feeling, coughing up a large amount of pink foamy sputum, and respiratory and circulatory failure if the rescue is not timely, and there is a risk of cardiac and respiratory arrest at any time. 2. Hypoxemia: In pulmonary edema, hypoxic pulmonary vasoconstriction leads to changes in intrapulmonary shunting, which can lead to uncorrectable hypoxemia, and even requires mechanical ventilation to restore ventilation. 3. Impact on pulmonary hemodynamics: acute pulmonary edema, often complicated by pulmonary hypertension, resulting in ventilation and blood flow disproportion, may form local thrombus and vascular occlusion caused by pulmonary atelectasis, acute respiratory distress syndrome or even life-threatening. When pulmonary edema occurs, it is necessary to consult a doctor in time and treat the cause under the guidance of a specialist.