Pulmonary embolism is a life-threatening pathological condition, mostly caused by dislodged deep vein thrombosis in the lower extremities, which is aggressive, but also caused by chest and lung diseases such as infections and tumors, which are more insidious in origin and develop gradually. With the increasing awareness of this disease, advances in imaging technology, and changes in the living environment, its diagnosis and incidence are increasing year by year. The typical clinical manifestations are sudden onset of chest tightness, chest pain, shortness of breath, coughing, starting with dry cough, later coughing pink sputum, bruising of the lips, nose and fingers, coma in severe cases, physical examination: increased heart rate, decreased blood pressure, especially systolic blood pressure decreased significantly, central venous pressure increased, systolic blood pressure can not rise even after a large number of fluids, which indicates a very serious condition, blood oxygen saturation is often below 80%, high concentration of oxygen also Oxygen saturation is often lower than 80%, and high concentration of oxygen can not improve oxygen saturation, and serious cases can die quickly without timely resuscitation or rapid thrombolytic drugs. However, some pulmonary artery embolism is not obvious because the pulmonary arteries involved are small and the alveoli affected are not large, so the clinical manifestations are not obvious, but only discovered during imaging, such as those caused by in situ infection and tumor in the chest and lungs, but the symptoms can be aggravated if not actively treated. The mechanism of the above clinical manifestations is that the thrombus in the deep vein of the lower extremity is loosened and dislodged, which can reach the heart along the inferior vena cava and block the pulmonary artery of the same caliber as the thrombus, causing the blood from the right heart not to return to the left heart, and the blood is stagnated in the right heart and pulmonary artery, resulting in an increase in the dead space of the alveoli, and the oxygen entering the alveoli and the CO2 gas in the blood cannot be exchanged effectively, resulting in a decrease in oxygenated hemoglobin and an increase in reduced hemoglobin in the blood. The brain tissue is particularly sensitive to hypoxia, and severe hypoxia leads to metabolic malfunction of brain cells and coma, which can lead to death if the vital center is affected. After pulmonary artery embolism, the affected alveoli and lobes, as well as the bronchi produce inflammation, which stimulates the production of chest pain, chest tightness, coughing, pink sputum if there is exudate or small blood vessel rupture, fluid accumulation in the alveoli, and pulmonary edema. As a result of increased return blood volume, pulmonary artery embolism, and enhanced contraction of the right heart, pulmonary hypertension occurs, and central venous pressure is often higher than 20 cmH2O, while right heart failure is easily caused by hypoxia. The blood flow from the right heart to the left heart is reduced, which makes the left heart diastolic filling poor, resulting in lower systolic blood pressure. This blood pressure is different from the general shock blood pressure, and a large amount of fluids cannot bring back the blood pressure. To prevent pulmonary embolism, we should prevent DVT in the lower extremities. DVT is more likely to occur in pelvic surgery, hip and knee surgery, as well as in tumor, trauma and infection, and anticoagulant drugs such as low molecular heparin can be applied appropriately at this time. After surgery, you should get out of bed as soon as possible to promote blood circulation and prevent DVT. If DVT has already appeared, a filter should be placed in the inferior vena cava in the following cases: 1. white swelling of the femur or bruising of the femur in the case of iliofemoral vein thrombosis; 2. ultrasound shows that the thrombus is floating and may fall off at any time; 3. DVT of the lower extremity and orthopedic surgery of the lower extremity is needed at the same time; 4. those with existing pulmonary embolism or recurrent pulmonary embolism; 5. those with DVT and family history of thrombosis; 6. surgical removal of the thrombus or catheter thrombolysis of the Preliminary work. The principles of treating pulmonary embolism are: massive infusion of anti-shock, oxygenation, protection of alveoli, reduction of inflammatory response, application of rapid and efficient thrombolytic agents, and protection of the central nervous system. Severe pulmonary embolism is a critical condition, and only timely detection and treatment can save the patient’s life. The central part of treatment is to relieve the pulmonary artery, and the two specific measures are the most critical, one is to increase the central venous pressure or pulmonary artery wedge pressure, and the other is rapid thrombolysis, and the speed of thrombolysis determines the success or failure of saving life.