Final answer:
A pulmonary embolism (PE) is a serious condition where a blood clot lodges in a pulmonary artery, obstructing blood flow to the lungs and potentially causing severe consequences including lung damage or death.
Step-by-step explanation:
The condition in which a clot or other material is lodged in the vessels of the lung is called a pulmonary embolism (PE). A direct answer to the question: A pulmonary embolism is a blood clot that has traveled through the blood vessels and become lodged in a pulmonary artery, which carries deoxygenated blood from the heart to the lungs.
When a deep vein thrombosis (DVT) occurs, for example, as depicted in Figure 17.8.1, the thrombus (blood clot) that forms can break off to become an embolus, traveling through the bloodstream. If it gets trapped in one of the pulmonary arteries, as seen in Figure 17.8.2, it causes a PE, alarming because it can block the transport of blood to the lungs. This can have severe consequences ranging from lung damage to instant death due to disrupted pulmonary circulation. Thrombi are typically aggregations of platelets, erythrocytes, and white blood cells trapped within fibrin strands, which can form within blood vessels due to various factors including injury to the vessel's lining, venous stasis, thrombophilia, and conditions like thrombocytosis, which is characterized by an excessive number of platelets heightening thrombosis risk.
Medical conditions such as thrombophilia or thrombocytosis can lead to an increased likelihood of clot formation, further increasing the risk of developing a PE. The embolus that causes PE is a serious medical emergency. Treatment often involves anticoagulants to prevent further clotting, and immediate medical attention is imperative to manage the pulmonary embolism and to maintain the flow of oxygen-depleted blood to the lungs.