Causes of Pulmonary Embolism

The most common cause of pulmonary embolism

Pulmonary embolism most often develops on the basis of deep vein thrombosis (syn. Phlebothrombosis). It often develops in the deep veins of the leg, especially in people with coagulation disorders or bedridden patients. However, they can also arise as a result of inflammation or trauma, or when the flow conditions change as a result of heart failure.

You might also be interested in: What are the chances of survival with a pulmonary embolism? and burning in the legs

But also:

  • central venous catheter,
  • Chemotherapy,
  • Hormone replacement therapies,
  • oral contraception especially in combination with nicotine,
  • pregnancy or
  • Breaks mainly of the hip / leg

can significantly increase the risk of clot formation.
These clots in the deep veins of the leg can loosen through sudden physical exertion, waking up in the morning or during pressure acts such as defecation and are then transported to the lungs by the venous blood flow system. This usually happens after a long period of rest, such as after lying down or sitting with bent legs for a long time, for example on a bus or plane.

Read more on the subject below: Detect thrombosis

Other, but less common, causes are fat embolism, a lump of fat that obstructs a pulmonary artery, which can occur after surgery or open hernias. But air embolism is also possible, which is usually caused by the doctor accidentally by inserting or pulling central venous catheters.

You can find more on the subject under: Treatment of pulmonary embolism

As soon as the vessels are too narrow for the Embolus it gets stuck and clogs the vessel. If the vessel is very small, there are no clinical symptoms at first. However, if a larger vessel is obstructed, the lungs can no longer be efficiently supplied with blood in this section and gas exchange does not occur.

In addition, it comes to due to the reduced blood flow Vasoconstriction the great pulmonary artery (Pulmonary contraction). This increases the Pressure load of the right Heart and the so-called arises Cor pulmonale. By the diminished Oxygen supply and an increased Dead space ventilation (Ventilation of non-perfused lung sections) creates an acute Lack of oxygen, especially des Heart muscle. This leads to a reduction in heart function and can ultimately lead to Circulatory shock with a drop in blood pressure and an increase in heart rate. A sinking of lung tissue (Pulmonary infarction) due to the lack of oxygen occur only in about 10% of all cases.

Tumor disease as the cause

Various factors can contribute to this Blood clot to lead. Are a factor malignant diseaseshow different malignant tumors. Most often it will be an accompanying Thrombosis in pancreatic and bronchial tumors observed, but it can occur in any type of cancer.

In the case of tumor diseases, the so-called Virchow's triad change, namely the composition of the blood, the blood flow and the vascular wall. Changes in these components of the vascular system almost always precede a thrombosis.

A pulmonary embolism can also occur in a tumor if the tumor grows into the vascular system and a fragment of the tumor is then flushed into the lungs via the vascular system. However, some tumors also release certain signal substances that promote blood clotting. This quickly leads to the formation of a blood clot, which can then dissolve and cause a pulmonary embolism.

Smoking as a cause

Smoke represents a significant risk factor for developing a thrombosis and secondary one Pulmonary embolism that contained in cigarettes nicotine has a constricting effect on the blood vessels and promotes at the same time the Blood clotting. This already brings together two factors that promote the formation of a blood clot.

In addition, smokers develop early Deposits on the vessel walls (Plaques) to which Accumulate blood lipids and platelets. It comes to Vasoconstrictionthat up to a Vascular occlusion can lead (peripheral arterial disease). In the worst case, smokers can lower Lose limbs (so-called Smoker's leg), if the lower extremities are poorly supplied with blood due to the narrowed or thrombosed vessels.

Particularly at risk for Thrombosis and pulmonary embolism are women who Smoke and at the same time the Birth control pills take (see: Risk of thrombosis of the pill). The contained sex hormones also work promoting blood clotting and in combination with smoking increase the risk of thrombosis again considerably. Smokers should definitely be informed about this risk.

Deep vein thrombosis as the cause

Deep vein thrombosis is the typical cause of pulmonary embolism. This creates a blood clot in a vein in the leg. The reason for this lies in changed blood flow velocities, changes in the vessel wall and a change in the coagulation system. Small thromboses can proceed without symptoms, with larger thromboses the foot on the affected side is swollen and the affected leg overheats. A pulmonary embolism occurs when the clot dissolves, is pumped back through the vessels into the heart and from there into the lungs. In the lungs, it clogs the blood vessels and can trigger a life-threatening embolism.

Read more on the subject at: Deep vein thrombosis

Pelvic vein thrombosis as the cause

Pelvic vein thrombosis is a blood clot that forms in a vein (the vessel that carries blood towards the heart). They are noticeable as sudden pain in the groin area and pain and swelling in the leg on the affected side. Possible causes are an increased coagulability of the blood and changes in the vascular wall. As with deep vein thrombosis, the blood clot can break loose. It is transported into the heart with the bloodstream and from there pumped into the lungs, clogs pulmonary vessels and thus triggers a pulmonary embolism.

Operation of a hip prosthesis / knee prosthesis as the cause

After the operation of a hip or knee prosthesis, affected people are usually immobile for a long time. In particular, the operated side must not be loaded at all or only slightly at the beginning. Blood, which is pumped from the heart through arteries into the legs, normally flows back to the heart against gravity through veins. The muscle action helps with every step to pump the blood forward a little. For this reason, non-exposure leads to changed flow conditions in the veins and therefore promotes the development of thromboses (blood clots). These can loosen and be pumped into the lungs, where they cause an embolism.

Fat embolism due to a fracture

A fat embolism is similar to a "normal" embolism, except that instead of a blood clot, a droplet of fat washed in is responsible for closing a blood vessel. Such a fat droplet can originate from the inside of a bone, for example. A large number of such fat droplets enter the bloodstream, especially if a bone breaks. Some of them can be pumped into the lungs and block the blood vessels there. Further complications of such a fat embolism arise when the droplets become entangled in the vascular system of another organ. There, too, the disturbed blood flow can severely damage the organ.

Use of the pill as a cause

The pill is extremely rare as the sole cause of pulmonary embolism.

Taking the pill can encourage pulmonary embolism, though other factors to be added. Your use as a sole cause pulmonary embolism or thrombosis (a blood clot in a vein) is relative unlikely. However, in recent years, thrombosis has occurred more frequently when taking Mini pillswhich contain a progestin (a sex hormone) as the only active ingredient.

For this reason, special attention should be given to the increased risk of thrombosis or a different preparation should be prescribed if other risk factors for thrombosis are known. There are other risk factors for thrombosis in addition to taking the pill, such as Smoke, an acquaintance Bleeding disorder or longer immobility through travel or surgery, it can cause pulmonary embolism.

More about this topic can be found: Thrombosis while taking the pill

Alcohol as the cause

Alcohol and smoking are well known Risk factorsthat can cause pulmonary embolism. On the one hand, this is due to the fact that the alcohol in the blood leads to the so-called INR increases. This value describes how quickly the blood clots and if the value increases, it means that the blood clots faster. This mainly affects people who drink alcohol regularly. If consumption is stopped, the value normalizes again.

Another reason why alcohol promotes pulmonary embolism is that alcohol is in the liver is dismantled. This can be the Limit the effect of blood thinnersthat also work in the liver. This applies to the drug, for example Marcumar ®, which many patients have to take because of a previous thrombosis or a cardiac arrhythmia. Alcohol also causes the Urine production in the kidney increases and you have to urinate more frequently. This increased dehydration in turn leads to a thickening of the blood, which can promote thrombosis or pulmonary embolism.

Drugs as the cause

Pulmonary embolism can occur for various reasons when using drugs. When applying stimulating drugs, how cocaine or Ecstasy, there is an increase in the heart rate and the Blood pressure. This can cause a thrombus, a blood clot that is already present, to detach from the wall of the vein and flush into the pulmonary circulation, where a pulmonary artery is obstructed. Furthermore, the use of these drugs raises strong sweat from and in combination with the often insufficient amount of water you drink, the blood thickens and a thrombosis can occur more easily. Another mechanism of action of the drugs is one Narrowing of blood vesselswhich can promote a heart attack and can be life-threatening with an existing thrombosis.

Gets a drug through a vein injected, this always means one irritation the vein, on the one hand by the chemical ingredients of the drug, on the other hand by pricking with a needle. If this vein is used frequently it can become a chronic phlebitis which can lead to a venous blood clot in the affected vessel. This blood clot can cause pulmonary embolism if it enters the lungs through the bloodstream.

Pregnancy as a cause

During pregnancy, women are particularly prone to pulmonary embolism. The coagulation system is also affected by the many hormonal changes that happen in the body. To protect against excessive blood loss during childbirth, the blood is made a little easier to clot. In addition, the blood from the veins flows back to the heart much more slowly. Both changes favor the development of thromboses (blood clots) in the veins. The clots can separate from the vein and travel to the heart in the bloodstream. From there, they are pumped directly into the lungs, block the vessels there and cause an embolism.

Why can sometimes no cause for a pulmonary embolism be found?

The cause of a pulmonary embolism is not always an obvious thrombosis, i.e. a blockage of a vein in a leg with a blood clot. Emboli can also from amniotic fluid during childbirth to be triggered.

Also one Air embolism can be a trigger, but it is more difficult to prove it, since it can only be detected by appropriate imaging, i.e. a Computed Tomography would have to be proven if it is found at all.

Pulmonary embolism is a serious clinical picture that, if not recognized in time, can lead to death. Not every family member wants one after the loss of a family member autopsy and so the cause of the pulmonary embolism may not be found. Different Blood tests Cannot be performed after death, as the properties of the blood change when a person has died.

There are several known causes of pulmonary embolism, and most of the time it is one Combination of different causes. In some cases, however, the person affected cannot remember any other causes that, in combination, led to the pulmonary embolism, such as prolonged immobility from sitting or lying down for long periods of time or taking various drugs that allow the blood to clot more quickly. The presence of cancer or surgery can also lead to pulmonary embolism.

The focus of treatment is always the pulmonary embolism itself and not its cause, as it is so dangerous.