What is the primary pathophysiological process occurring in pulmonary embolism (PE)?

The primary pathophysiological process that occurs in pulmonary embolism (PE) is the obstruction of pulmonary arteries. This obstruction is typically caused by a blood clot that travels to the lungs from the deep veins of the legs or other regions (a condition known as deep vein thrombosis, or DVT). When this clot lodges in the pulmonary arteries, it impedes blood flow to the lung tissue, which can lead to decreased oxygenation of the blood, increased pulmonary vascular resistance, and potential right heart strain.

This obstruction is critical because it alters the normal perfusion of the lung, leading to the development of hypoxemia and subsequent respiratory distress. The severity of the symptoms and overall impact on the patient can vary depending on factors such as the size of the embolus and the number of arteries involved.

Infection in lung tissue, inflammation of pleural lining, and compression of the lung by effusion are not the primary mechanisms involved in pulmonary embolism. While these factors may affect respiratory function, they do not define the pathophysiology of PE, which fundamentally centers around the blockage of blood flow due to emboli in the pulmonary circulation.