[Etiology] 1. Core information: emboli from other sites, blocking the pulmonary vessels, resulting in pulmonary circulation blockage. 2, pro-coagulation status: estrogen, contraceptives, coagulation factors; protein C, S deficiency; thrombotic tendency; tumor. 3.Deep vein thrombosis: mainly from the deep veins of lower limbs, such as femoral veins: lower limb braking (surgery, trauma), pregnancy, obesity, tumor. 4, vascular factors: direct injury caused by venous catheter (vascular endothelial injury). [Pathogenesis] 1. Hypoxia: leads to cyanosis of the skin/mucous membranes, difficulty in inspiration, and shortness of breath. Acute pleurisy leads to chest pain on inhalation. 2. Severe state: When the pulmonary vessels are completely blocked, it leads to interruption of blood flow and sudden extreme hypotension (sudden decrease in pulmonary return blood volume), and if it reaches this level, there is a high risk of sudden death. 【Diagnosis】 1.Impact study: Chest X-ray alone cannot confirm the diagnosis; CT pulmonary angiography should be preferred; manifestation of significant changes in ventilation and perfusion in the embolized area; auxiliary deep vein thrombosis-related tests. 2.Blood tests: D-Dimers, CBP, PT, aPTT, TT, ESR, RFTs, LFTs, electrolytes. 3.Electrocardiogram: RBBB, sinus tachycardia. 4, S1Q3T3 signs characteristic of pulmonary embolism: large S wave in lead I; large Q wave in lead II; T wave flip in lead III. Symptoms/signs】 1.Whistle-related symptoms: dyspnea, shortness of breath, chest pain, cough, pink foamy sputum (hemoptysis), cyanosis. 2, chest features: percussion sounds are diminished, whistling sounds and speech resonance can be heard, and pleural friction sounds may be present. 3. Jugular venous pulsation: If JVP and hepatic congestion are present, it is a sign of right heart failure. 4.Peripheral edema: due to secondary right heart failure, and ascites and lower limb edema. 【Treatment】 1.Thrombolytic therapy: If it is caused by thrombus. 2.Medication: anticoagulants (warfarin), heparin, sulforaphane. 3.Inferior vena cava filter: it can effectively organize the subsequent lower limb deep vein thrombosis.