Pulmonary Embolism: Symptoms, Causes and Diagnosis

A pulmonary embolism occurs when a blood clot travels into an artery in the lungs, partially or completely blocking it. In the worst case, a pulmonary embolism can be life-threatening. What are the typical symptoms of a pulmonary embolism, what are the causes of its development and how is the diagnosis made?

Causes of a pulmonary embolism

The right heart pumps the oxygen-poor blood from the body into the large and small arteries of the pulmonary system. In these it is brought to the pulmonary alveoli, where it is again enriched with oxygen.

Sometimes, however, the blood from the body not only brings carbon dioxide with it to breathe out, but also washes up  dangerous particles  : mostly blood clots from a  thrombosis  in the leg veins, but also – much more rarely – fat, for example after a bone operation, air through a Infusion, bacteria, tumor cells or amniotic fluid entering the maternal system during childbirth. These substances can get stuck and clog the corresponding vessel.

In most people, the pulmonary embolism results from a blood clot that has formed in veins in the pelvis or legs (leg vein thrombosis). Small particles detach from these “baked” blood cells and are carried on with the bloodstream. The veins first widen and eventually empty into the portal vein, which leads to the right heart. Only in the lungs do the vessels branch out again and become narrower and narrower. That is why the particles only settle there again and block the vessel.

If the clot is only in a small artery, this may go unnoticed; if a larger or more vessels are affected, this can lead to a severe, life-threatening clinical picture.

Pulmonary embolism: symptoms and signs

If particles settle in the blood vessel, the blood accumulates in front of it, slowing down its flow, which can lead to more and more  clots  forming in the pulmonary vessels. The heart has to pump against this suddenly increased pressure and not enough blood gets to the left side of the heart. This in turn leads to a drop in blood pressure on the one hand and the coronary arteries no longer being supplied with enough blood, which reduces cardiac output, and on the other hand that too little oxygen-rich blood reaches the body and the organs.

In addition, the body lacks oxygen because no blood can get into the lung area behind the closed vessel and therefore there is less space available for oxygen exchange.

The severity of the symptoms of a pulmonary embolism varies – depending on the number and size of the affected vessels and how quickly they close.

Typical  symptoms  of a pulmonary embolism include:

  • slight  shortness of breath  to severe breathing difficulties
  • (bloody)  cough
  • chest pain
  • anxiety
  • fear of death
  • racing heart
  • Shock symptoms such as loss of consciousness and cardiac arrest

Possible early detection of a pulmonary embolism?

A large embolism is often  preceded by several small ones, which become noticeable  through signs such as brief  dizzy spells  , palpitations and  tachycardia  . If there are also signs of  venous thrombosis  (swollen, warm leg with a feeling of tension or pain), urgent medical advice should be sought even if these symptoms are milder.

pulmonary embolism and corona

The risk of a pulmonary embolism or leg vein thrombosis is significantly increased in severe corona patients. For example, study results from the University Hospital in Vienna showed that 18 to 28 percent of those affected who had to be treated in intensive care developed a pulmonary embolism or leg vein thrombosis.

Researchers attribute this to a possible influence of the  corona virus  on blood clotting. This is also reflected in an increased D-dimer concentration in the blood of those affected. D-dimers are  proteins that are formed when blood clots are broken down by the body.

In connection with the  corona vaccine  from  AstraZeneca  , pulmonary embolisms have also occurred in individual cases after vaccination. An influence of the vaccine on the blood platelets ( thrombocytes ) involved in blood clotting is also assumed to be the cause here.

Risk factors for pulmonary embolism

A pulmonary embolism often occurs as a result of deep vein thrombosis in the leg, as the blood clot travels from the leg to the lungs. The following groups of people are therefore at a higher risk of suffering from a pulmonary embolism:

  • Bedridden and immobile people  are  particularly at risk for venous thrombosis and thus pulmonary embolism.
  • After an operation  , the risk of thrombosis is very high, especially if this is associated with prolonged immobility (bedridden for more than three days).
  • Patients with  varicose veins  or heart disease  are at increased risk.
  • Obesity  and the  pill  also increase the risk of pulmonary embolism, especially in combination with  smoking.
  • Embolisms occur frequently in  drug addicts who  inject their addictive substance.
  •  The risk is five times higher in  pregnant women .

There are also some diseases in which the blood’s tendency to coagulate is increased, such as chronic inflammatory bowel diseases,  diabetes  mellitus and some malignant tumors. Genetic factors such as disorders of hemostasis (hemostatic) can also increase the risk of thrombosis. These people are particularly at risk on long-haul flights, for example, where you sit for a long time in a position where the leg veins are kinked.

How is a pulmonary embolism diagnosed?

When taking the medical history (anamnesis) and the  physical examination  – in addition to asking about the current symptoms – the main thing is to look for risk factors and signs of thrombosis. The first indications of an embolism can arise when listening to the heart and lungs.

In the  laboratory tests  , blood gases, coagulation values ​​and D-dimers are of particular importance. The former give an impression of the body’s oxygen supply and thus the severity of the possible embolism, the coagulation values ​​provide information about certain risk factors, an increase in D-dimers shows that there is increased activity of fibrinolysis, i.e. the breakdown of blood clots. A normal X-ray examination of the lungs and an ECG are rather unspecific and at most strengthen the suspicion or rule out other causes.

An  ultrasound scan  can provide clues about the strain on the right heart; sometimes a large clot can also be seen. Lung scintigraphy , in which  radioactively labeled substances are injected, can be used to assess and compare blood flow and ventilation in the lungs. Certain images suggest a pulmonary embolism but do not allow a definitive diagnosis.

CT angiography is more suitable for this  , in which an X-ray contrast agent is injected into the vein – as when taking blood – and its accumulation in the vessels is shown in the spiral CT. However, small embolisms in the peripheral areas cannot be shown with this – a catheter must then be inserted through the artery ( pulmonary angiography ).

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