The following groups of people are at higher risk of developing pulmonary embolism:
- Bedridden and immobile people are particularly at risk for venous thrombosis and, consequently, pulmonary embolism.
- After surgery, the risk for thrombosis is very high; if the affected person then stands up or presses hard during defecation, a clot can detach and reach the lungs.
- Patients with varicose veins or with heart disease are at increased risk.
- Obesity and the pill also increase the risk of pulmonary embolism, especially in combination with smoking.
- In drug addicts who inject their addictive substance, embolisms occur more frequently.
- In pregnant women, the risk is increased fivefold.
In addition, there are some diseases in which the tendency of the blood to clot is increased, such as cirrhosis of the liver and some malignant tumors. Such patients are particularly at risk, for example, on long-haul flights – where people sit for long periods in a position where leg veins are kinked.
Pulmonary embolism: symptoms and signs
The range of symptoms of pulmonary embolism – depending on the number and size of the affected vessels and how quickly they close – extends from mild shortness of breath to severe difficulty breathing, coughing, chest pain, feeling of anxiety, fear of death, palpitations, and shock symptoms such as loss of consciousness and cardiovascular arrest.
Often, a large embolism is preceded by several small ones, which are indicated by signs such as short-lived dizziness, heart palpitations, and palpitations. If, in addition, signs of venous thrombosis appear (swollen, warm leg with a feeling of tightness or pain), a doctor should definitely be consulted even for such discrete symptoms.
How is pulmonary embolism diagnosed?
When taking the patient’s medical history (anamnesis) and performing a physical examination – in addition to asking about current symptoms – the physician primarily looks for risk factors and signs of thrombosis. Initial indications of an embolism may be obtained by listening to the heart and lungs.
The most important laboratory tests are blood gases, coagulation values and D-dimers. The former give an impression of the oxygen supply to the body and thus the severity of the possible embolism, the coagulation values provide indications of certain risk factors, and an increase in D-dimers shows that there is increased activity of fibrinolysis, i.e., the breakdown of blood clots. A plain radiographic examination of the lungs and an ECG tend to be nonspecific and, at best, may strengthen suspicions or rule out other causes.
An ultrasound examination may provide clues to right heart strain; sometimes a large clot can be shown. Lung scintigraphy, in which radioactive labeled substances are injected, can assess and correlate blood flow and ventilation to the lungs. Certain images are indicative of pulmonary embolism, but do not allow a definitive diagnosis.
CT angiography, in which an X-ray contrast medium is injected into the vein – as in blood sampling – and its accumulation in the vessels is visualized on spiral CT, is better suited for this purpose. However, small emboli in the peripheral areas cannot be shown with this – a catheter must then be inserted via the artery for this (pulmonary angiography).