Symptoms depend on how completely the pulmonary artery is blocked and on the person's overall health. Symptoms are more serious if the person also has a serious disease, such as chronic obstructive pulmonary disease or coronary artery disease.
Some symptoms may include:
- Light-headedness, fainting or seizures because not enough oxygen-rich blood is getting to the brain and other organs
- Irregular heartbeats
- Bluish skin (cyanosis)
- Sudden death
The symptoms of pulmonary embolism usually develop suddenly. By contrast, signs of pulmonary infarction (tissue death) develop slowly over several hours after the pulmonary embolism occurred. Pulmonary infarction may cause coughing that produces bloodstained sputum, sharp chest pain when breathing in and sometimes a fever. These symptoms often last several days, growing milder with each passing day.
Causes and Risk Factors
An embolism may be any of a variety of things, including:
- A blood clot is the most common type of embolus that blocks the lungs. It usually forms in a leg or pelvic vein when a person has remained in one position for a long time. Examples include being on bed rest for a long period of time or sitting in one position while traveling by air. Once a person begins moving again, the clot can break loose. Sometimes - but more rarely - blood clots form in the veins of the arms or in the right side of the heart.
- Fat, which can escape from the bone marrow when a bone is fractured. This is relatively rare.
- Amniotic fluid, which may be forced into the pelvic veins during childbirth. This also is relatively rare.
- Cancerous tumor fragments, which may break free into the blood stream
- Air bubbles, which can not only block blood flow if they are large but also prevent the heart from effectively pumping blood. The air bubble may be introduced during intravenous delivery of drugs, nutrients or fluids. An air bubble embolism may also form when a vein is operated on or when a person is being resuscitated because of the force of having pressure put on their chest. Underwater diving can cause an air embolism; the risk depends on how deeply the person dives and how fast he or she returns to the surface of the water.
A person is at greater risk of developing blood clots in the veins if any of the following factors are present:
- Advanced age
- Blood clotting disorder
- Heart attack or failure
- Irregular heartbeat (atrial fibrillation)
- Major surgery
- Pelvis, hip, or leg fracture
- Prior blood clot
- Prolonged bed rest or sitting during a long car or plane trip
- Use of oral contraceptives, especially by a smoker after age 35