4.10
肺栓塞 I: 简介
血凝块，即血栓，是由纤维蛋白、血小板和红细胞组成的半固体团块。当其在血管内形成时，可能阻塞血流，这种情况称为血栓形成。如果血栓的一部分脱落，就会形成栓子，栓子可随血流迁移并阻塞远处血管。当这种情况发生在肺动脉时，就会导致称为肺栓塞，即 PE，的疾病。
起源和影响
在大多数情况下，栓子来源于下肢深静脉…
血栓是在血管内形成的凝血块，可部分或完全阻塞血流。这种状况被称为血栓形成。
如果血凝块的一部分脱落并随血流移动，就会形成栓子。
如果栓子阻塞肺动脉，可能导致肺栓塞（PE）。在大多数情况下，栓子来源于下肢深静脉中的血栓，这种情况称为深静脉血栓形成。
肺栓塞（PE）的发生机制可用魏尔啸三联征解释，包括静脉血流淤滞、高凝状态和内皮损伤，这三个因素均促进血栓形成。
静脉淤血可能由长时间不动引起，例如骨科手术后或长时间坐着，如乘坐长途飞机。
高凝状态可能由抗凝血酶Ⅲ缺乏、妊娠或使用含雌激素的避孕药等状况引起。
内皮损伤可能由创伤或中心静脉导管插入引起。
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Q1: What is the difference between a thrombus and an embolus?
A thrombus is a blood clot that forms within blood vessels and can block blood flow, a condition called thrombosis. An embolus forms when part of the thrombus breaks away and travels through the bloodstream. If the embolus lodges in a pulmonary artery, it causes a pulmonary embolism.
Q2: What is deep vein thrombosis and how does it relate to pulmonary embolism?
Deep vein thrombosis (DVT) is a blood clot that forms in the deep veins of the legs. In most cases, the embolus that causes pulmonary embolism originates from a thrombus in these deep leg veins. DVT and PE together are considered part of the same disease process called venous thromboembolism.
Q3: What are the three factors in Virchow's triad that contribute to blood clot formation?
Virchow's triad includes venous stasis, hypercoagulability, and endothelial injury. Venous stasis occurs when blood flow slows due to immobility from surgery or prolonged sitting. Hypercoagulability results from conditions like antithrombin III deficiency or pregnancy. Endothelial injury may be caused by trauma or catheterization.
Q4: What causes venous stasis and who is at risk?
Venous stasis occurs when blood flow becomes stagnant due to immobility. Risk factors include prolonged bed rest after orthopedic surgery, extended plane flights, heart failure, obesity, pregnancy, and catheter use. Any condition limiting movement can slow blood circulation in the veins.
Q5: What conditions increase blood coagulability and raise pulmonary embolism risk?
Hypercoagulability can be inherited, such as factor V Leiden or protein C/S deficiency, or acquired through malignancy, oral contraceptives, pregnancy, or inflammatory disorders. These conditions increase the tendency of blood to clot, raising the risk of thrombus formation and subsequent pulmonary embolism.
Q6: How can endothelial injury contribute to pulmonary embolism development?
Endothelial injury damages the inner lining of blood vessels, activating clotting pathways that promote thrombus formation. Trauma, surgery, or prior thrombosis can cause this vessel wall damage. When a resulting clot dislodges and travels to the lungs, it causes pulmonary embolism.
Q7: Why are hospitalized and cancer patients at higher risk for pulmonary embolism?
Hospitalized and cancer patients face increased risk due to immobility, inflammation, and procoagulant states that promote blood clotting. These factors align with Virchow's triad mechanisms: reduced blood flow, increased clotting tendency, and vessel damage. Understanding these mechanisms supports early detection and prevention strategies in chronic obstructive pulmonary disease clinical contexts.