Pulmonary embolism

Pulmonary embolism (pulmonary venous thromboembolism, PE) is a life-threatening complication of thrombus formation within the veins.

Description

Pulmonary embolism is the obstruction of the pulmonary artery and/or its branches by the thrombus originating from the deep veins of the limbs, less frequently – from the veins of the pelvis and abdomen or the right chambers of the heart, namely, in case of atrial fibrillation. When the thrombus blocks the blood flow in the pulmonary artery or its branches gas exchange in the lung is compromised, if the blood clot is large enough to obstruct the outflow from the right ventricle, acute right heart failure develops and sudden death may happen. 

Pulmonary embolism word cloud on grey background
Pulmonary embolism word cloud on grey background

Causes and classification

  • “Primary” pulmonary embolism is an accident which occurs in the absence of any surgical intervention or trauma. PE is caused by the coagulation disorders with a tendency towards thrombi formation induced by some other illnesses such as cancer and heart failure, oral contraception use, prolonged immobilization, pregnancy and baby delivery;
  • So-called “secondary” pulmonary embolism is associated with previous major surgeries or traumatic injuries and may occur up to a month after the discharge from the hospital;

Deep vein thrombosis is the most common cause of pulmonary embolism.

Risk factors

Symptoms of pulmonary embolism

The signs of pulmonary embolism depend on the extent of the embolism and the diameter of the involved vessel and injured lung. If the small vessel is affected a person may be completely asymptomatic, whereas larger embolism compromise blood circulation and may even cause sudden cardiac arrest and death.

Pulmonary embolism is usually associated with the sudden onset of the following symptoms:

  • Breathlessness, especially on exertion;
  • Coughing up blood (hemoptysis);
  • Chest pain;
  • Tachypnea (rapid breathing);
  • Distended neck veins;
  • Bluish discoloration of the nose and area around the mouth and on the tips of the fingers (peripheral cyanosis);
  • Leg swelling;
  • Low grade fever;
  • Syncope (fainting);

On the other hand, the symptoms of deep vein thrombosis may also be present (suggesting the origin of the thrombus) including:

  • Pain in the injured limb and its bluish appearance;
  • Swelling of the affected leg/arm with erythema and warmth over the vicinity of the clot;
  • A cord may be palpated along the involved vein.

Diagnosis

  • D-dimer levels rise in pulmonary embolism and deep vein thrombosis due to the breakdown of fibrin. Of note, detection of D-dimer is not necessarily specific for PE and may increase in a large number of other conditions such as myocardial infarction, cancer, sepsis and even pregnancy;
  • Arterial blood gases reveal low oxygen concentration (hypoxaemia), reduced levels of carbon dioxide in the blood (hypocapnia);
  • Electrocardiography is used to exclude myocardial infarction;
  • Chest X-ray is helpful to exclude pneumonia, pneumothorax or any other diagnosis from the pulmonary embolism;
  • CT pulmonary angiography is the gold standard for the diagnostics of pulmonary embolism;
  • Vein ultrasound is performed to detect thrombi in the deep vein of the extremities which may give rise to thromboemboli;

Treatment

Oxygen should be given to all persons who have hypoxemia in order to increase oxygen saturation and provide oxygen supply to organs and tissues of the body. Narcotic analgetics may be given to relieve pain and thus reduce shock. However, sometimes NSAIDs may be effective enough to decrease pleuritic pain.

Thrombolysis is the mainstay for pulmonary embolism treatment as it can dissolve the thrombus and restore the blood flow in the affected vessel. Anticoagulants are recommended to reduce thrombus formation, reduce growth of the thrombus and prevent further thromboembolism.

Rarely surgical resection of the embolus may be performed when other treatment is not effective or contraindicated.

Inferior vena cava filter – is a vascular filter implanted into the inferior vena cava to prevent the distribution of the thrombi from the lower extremities to lungs in individuals who are at high risk of pulmonary embolism and if the anticoagulants were not effective.

Prevention

Some genetic features are associated with a person’s predisposition to thrombi formation and may be detected with the help of our genetic test.   As long as pulmonary embolism is a life-threatening condition it is essential to detect individuals at high risk of developing thromboembolism and taking measures in order to prevent it – initiating anticoagulant therapy or implantation of vena cava filter and wearing medical compression stockings  which significantly reduce the risk of thrombosis.

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