What condition results from a blood clot, thrombus, air embolism, or other particle lodging in the pulmonary artery?

• A. Pulmonary embolism
• B. Pulmonary edema
• C. Pulmonary hypertension
• D. Cor pulmonale

Answer: (A)

A pulmonary embolism occurs when a clot, thrombus, air bubble, or other particle becomes lodged in the pulmonary artery and blocks blood flow to portions of the lung. This obstruction prevents perfusion to some lung tissue despite ongoing ventilation, causing a mismatch between air reaching the alveoli and blood flowing through the capillaries. The result is hypoxemia and can lead to rapid strain on the right side of the heart if the blockage is large.

This is different from pulmonary edema, which is fluid buildup in the alveolar spaces typically from left-sided heart failure; pulmonary hypertension, which is a chronic rise in pulmonary artery pressure; and cor pulmonale, which is right heart failure due to chronic lung disease. The defining feature here is the abrupt vascular blockage in the lungs by an embolus.