Pulmonary embolism

A blockage (blood clot) of the main artery of the lung.

A blockage of a pulmonary artery by a blood clot.

Occlusion of one or more of the pulmonary arteries by a thrombus, which almost always originates in the leg veins from blood stasis, vessel injury, or changes in clotting factors.

A blood clot in the lungs, sometimes a cause of maternal mortality.

Blockage of a pulmonary artery by foreign matter or a thrombus (blood clot); it is characterized by difficult breathing, and sharp chest pain worsened by deep inspiration. If severe, shock and bluish discoloration of the skin (cyanosis) can develop, as can pleural effusion, heart rhythm abnormalities, and death. Predisposing factors include pro¬ longed immobilization, especially associated with surgery; blood-vessel-wall damage; and factors that increase the tendency of the blood to clot. Treatment is by anticoagulants and oxygen. In some cases, either surgery to remove the clot or administration of a thrombolytic drag may be used.

The sudden blockage of an artery in the lung, usually by a blood clot that has traveled through the bloodstream. A pulmonary embolism may also be caused by tumor tissue, piece of fat, an air bubble, or, in pregnancy, by amniotic fluid. In most cases, other unblocked arteries can deliver sufficient blood to the affected area of the lung to prevent death of lung tissue. When a large blood vessel is blocked or when there is underlying lung disease, the amount of blood may be inadequate to prevent lung tissue death, a condition called pulmonary infarction.

Obstruction of the pulmonary artery or one of its branches by an embolus, usually a blood clot derived from phlebothrombosis of the leg veins. Large pulmonary emboli result in acute heart failure or sudden death. Smaller emboli cause death of sections of lung tissue, pleurisy, and hemoptysis (coughing of blood). Minor pulmonary emboli respond to the anticoagulant drugs heparin and warfarin. Major pulmonary embolism is treated by embolectomy or by dissolution of the blood clot with an infusion of streptokinase. Recurrent pulmonary embolism may result in pulmonary hypertension.

The condition in which an embolus, or clot, is lodged in the lungs. The source of the clot is usually the veins of the lower abdomen or legs, in which clot formation has occurred as a result of the occurrence of deep vein thrombosis (DVT) thrombophlebitis. Thrombophlebitis, with or without pulmonary embolism, is a not uncommon complication of surgical operations, especially in older patients. This is one reason why such people are got up out of bed as quickly as possible and are encouraged to move and exercise their legs regularly while in bed. Long periods of sitting, particularly when travelling, can cause DVT with the risk of pulmonary embolism. The severity of a pulmonary embolism, which is characterized by the sudden onset of pain in the chest, with or without the coughing up of blood, and a varying degree of shock, depends upon the size of the clot. If large enough, it may prove immediately fatal; in other cases, immediate operation may be needed to remove the clot; whilst in less severe cases anticoagulant treatment, in the form of heparin, is given to prevent extension of the clot. For some operations, such as hip-joint replacements, with a high risk of deep-vein thrombosis in the leg, heparin is given for several days post-operatively.

An obstruction of the pulmonary artery or one of its branches, usually caused by an embolus from a blood clot in a lower extremity. Roughly 10% to 15% of patients with the disease will die. Risks for it include genetic predisposition, recent limb or pelvic fracture, other trauma, burns, surgery (especially joint replacement [knee, hip]), long-term immobility, enforced immobilization (long car or plane trips or hospitalization), pregnancy, use of estrogen-containing hormonal contraceptives, postmenopausal hormones, atrial fibrillation, vascular injury, IV drug abuse, polycythemia vera, heart failure, autoimmune hemolytic anemia, sickle cell anemia, thrombocytosis, dehydration,, advanced age, cancer, and obesity. Diagnosis is challenging because symptoms are nonspecific and often misinterpreted and may mimic many other diseases of the limbs, abdomen, or chest. It is often assumed that a sudden, unexpected death occurring after a hospitalization was caused by an unsuspected PE. PE is currently the third most common cause of death in the U.S. When a pulmonary embolism is suspected, evaluation includes oximetry, chest x-ray, blood tests for Ddimer, and depending on local hospital practices, duplex venous ultrasonography of the legs, ventilation/perfusion scanning, or multidetector CT angiography of the chest. Pulmonary angiography was formerly the gold standard test but is invasive, poses some risk to the patient, and requires angiographic skill and excellent radiographic equipment. It is now rarely performed. Treatment includes the administration of anticoagulants (low molecular weight heparins or unfractionated heparins, followed by oral warfarin). Oxygen is administered as prescribed by nasal cannula or mask. In critically ill patients, intubation and mechanical ventilation may be required. Thrombolytic drugs may be needed for massive emboli, i.e., those that cause shock or that impair the filling of the right atrium and ventricle with blood. Thrombolectomy may be attempted in critically ill patients, when a competent surgical team is available.