What is a pulmonary embolism primarily caused by?

A pulmonary embolism is primarily caused by a blood clot that travels to the lungs from the deep veins of the legs or other parts of the body, a condition known as deep vein thrombosis (DVT). When a blood clot detaches from its original site and travels through the bloodstream, it can lodge in the pulmonary arteries, blocking blood flow to lung tissue. This blockage can lead to significant complications, including reduced oxygen levels in the blood, strain on the heart, and potentially life-threatening conditions.

Understanding this mechanism is crucial in respiratory care, as it emphasizes the importance of preventive measures for at-risk individuals, such as those who are immobile, have had recent surgery, or suffer from conditions that increase clot risk. Other conditions like air in the pleural cavity (which relates more to pneumothorax), pneumonia, and lung scarring pertain to different respiratory pathologies and do not cause pulmonary embolism.