When an embolus becomes lodged in a pulmonary blood vessel, it prevents adequate blood supply to the lung, interferes with the exchange of oxygen and carbon dioxide, and results in arterial hypoxemia. As pressure within the obstructed pulmonary artery increases there is strain on the right ventricle and it may eventually fail. Two other complications of PE are pulmonary infarct and pulmonary hemorrhage. Signs and symptoms of PE vary greatly, depending on the extent to which the lung is involved, the size of the clot, and the general condition of the patient. Simple, uncomplicated embolism produces such cardiopulmonary symptoms as dyspnea, tachypnea, persistent cough, pleuritic pain, and hemoptysis.
Apprehension is a common symptom.
On rare occasions the cardiopulmonary symptoms may be acute, occurring suddenly and quickly producing cyanosis and shock. The drug most often used in the treatment of PE is heparin, which prolongs clotting time and allows the body time to resolve the existing clot. Patients with massive embolism or an ascending thrombophlebitis are sometimes treated with fibrinolytic agents, such as streptokinase and urokinase, which dissolve the clot. Major goals in the care of patients at risk for pulmonary embolism are prevention and early detection. Those who are at risk and require diligent preventive measures and periodic monitoring are patients who have had surgery or cardiovascular disease associated with clot formation, e.g., patients after myocardial infarction and stroke, patients with multiple trauma, and patients who are therapeutically immobilized.