Pulmonary Embolism FAQ 1.What is pulmonary embolism? Pulmonary embolism is a pathological process in which dislodged thrombus or other substances block the pulmonary artery or its branches, and the common source of thrombus is lower limb vein. Especially when the lower extremity movement is impaired due to various reasons and after being bedridden for a long time, the thrombus is formed in the veins of the lower extremity, which will suddenly dislodge after activity and enter the pulmonary artery through the venous access, causing acute embolism. After the occurrence of pulmonary embolism, the embolized part of the lung tissue is unable to carry out blood-oxygen exchange because of the sudden loss of effective circulating blood flow, and can cause significant hypoxemia due to other body fluids and other reactions, resulting in tracheospasm. When the pulmonary artery is blocked, the local blood supply resistance increases, which greatly increases the workload of the right heart and can lead to acute right heart failure, aggravate hypoxemia, and even cause serious conditions such as shock. Pulmonary embolism is a condition with hemodynamic changes, and the treatment also focuses on correcting the hemodynamic changes without overly pursuing the perfection in imaging (such as the total removal of emboli). 2.What are the common symptoms and causes of pulmonary embolism? There is diversity in the presentation of pulmonary embolism depending on the degree of hemodynamic impact of the embolism. Mild pulmonary embolism may be detected only occasionally during examination without obvious clinical manifestations or with only very mild breath-holding symptoms; while severe pulmonary embolism can directly lead to sudden death. Generally speaking, pulmonary embolism starts suddenly, and patients will suddenly experience unexplained deficiency, pale face, cold sweat, those with difficulty in breathing, chest pain, cough, and even fainting. In addition, because pulmonary embolism directly affects oxygen supply, the brain is most sensitive to hypoxia, and patients can be accompanied by symptoms of cerebral hypoxia: such as anxiety, fear, nausea, convulsions, etc., and in severe cases, they can be comatose. The most common cause or source of embolism in pulmonary embolism is still lower extremity venous thrombosis. Except for very special constitution, lower extremity venous thrombosis is usually directly related to reduced activity or even inactivity of lower extremities, such as lower extremity braking after trauma or surgery, or loss of lower extremity mobility due to various reasons (e.g. hemiplegia); when special conditions in other parts affect lower extremity blood flow return, such as pregnancy, abdominal tumor, etc.; the effect of special surgery, such as laparoscopic surgery, because the abdominal cavity maintains continuous high pressure during surgery, venous return will therefore slow down, etc.