Pulmonary Embolism

What is a Pulmonary Embolism (PE)?

Pulmonary embolism is a total or partial occlusion of one or more pulmonary arteries by a thromboembolic event. PE occurs when blood clots dislodge from deep veins of the legs, thigh, or pelvis travel through the bloodstream and lodge in the lung. Other materials such as fat, air, and a tumor can dislodge and cause PE as well. Pulmonary embolism can be life-threatening because clots cause occlusion of blood flow to the lungs leading to hypoxemia, permanent lung damage, and damage to vital organs in the body due to hypoperfusion.

What is the epidemiology of Pulmonary Embolism?

In the United States, approximately 200,000 people will have new or recurrent PE diagnosed each year and it is estimated that PE accounts for over 100,000 annual death. It is of crucial importance to recognize and treat pulmonary embolism quickly to prevent complications and death.

What is the nomenclature of Pulmonary Embolism?

PE can be classified based on how the patient present and their hemodynamic stability. The patient can present acutely and show symptoms immediately after the pulmonary vessel occlusion and others can be subacute which takes days or weeks before showing symptoms or it can be chronic PE which takes years for symptoms to manifest.  Hemodynamically unstable patients are likely to suffer from massive PE and they usually present with significant hypotension that requires vasopressors. Hemodynamically unstable PE carries the worst prognosis and death often occurs within a few hours of presentation. 

PE can also be classified based on the anatomical location of the clot in the lungs which are listed below:

  • Saddle
  • Lobar
  • Segmental
  • Subsegmental

What is the pathogenesis of Pulmonary Embolism?

Blood clots occur when conditions such as thrombophilia tip the balance of coagulation-fibrinolysis toward excessive clotting. PE can be provoked on unprovoked. Most emergency room visits are due to unprovoked pulmonary embolism.  Provoked PE are usually consequences of Virchow’s triad.

What are risk factors of Pulmonary Embolism?

  • History DVT or PE
  • Surgery especially those that involve hips, knees or pelvis
  • Cancer
  • Immobilization 
  • Obesity
  • Pregnancy
  • Hormone-based medicines
  • Smoking
  • Genetics: factor V Leiden and prothrombin gene mutation

What are symptoms of Pulmonary Embolism?

Half of the patients with pulmonary embolism are asymptomatic but common symptoms along with leg pain and swelling are:

  • Shortness of breath 
  • Chest pain while taking a deep breath
  • Coughing 
  • A rapid heart rate
  • Dizziness or fainting

How to diagnose Pulmonary Embolism?

A detailed history and physical examination are required for the diagnosis of PE. Diagnostics test such as D-dimer and Computed tomography pulmonary angiography (CTPA) are often required to confirm or exclude the diagnosis of pulmonary embolism. A ventilation/perfusion lung scan is also used in some cases if the patient is not a candidate for CTPA. An ECG may show T-wave inversion in leads V1- V4, which is indicative of RV strain. Other findings include tachycardia, S1Q3T3, and new-onset atrial fibrillation or flutter.

What are the Differential Diagnoses of Differential Diagnosis?

  1. Pneumonia
  2. Congestive heart failure
  3. Pneumothorax

How to Treat Pulmonary Embolism?

Treatments of pulmonary embolism aim at dissolving old clots and preventing new clots from forming. Some of the treatment’s options are listed below:

  • Anticoagulation:  These medications are known as blood thinners. They work by preventing new clot formation and it is recommended to takes these medications as prescribed by the physician for at least 3 months.
  • Inferior vena cava filter (IVC):  This option is recommended for patients at significant bleeding risk if they use anticoagulant. The filter blocks the circulation of clots in the bloodstream preventing them from traveling into the lungs.
  • Thrombolytics: These medications are known as clot busters and are used in a life-threatening situation to dissolve large blood clots. It carries the risk of serious bleeding and is used in a patient with low bleeding risk.
  • Embolectomy: This is a procedure in which the clot is removed from the lung usually using a catheter. It is considered if the patient fails or not a candidate for thrombolytics.

How to Prevent Pulmonary Embolism?

  • Using anticoagulants are prescribed by the physician can prevent a new clot from forming and thus preventing another episode of PE
  • Use of graduated compression stockings to provide the pressure needed for blood flow through your leg while preventing deep vein thrombosis (DVT)
  • Embrace a healthy lifestyle by quit smoking, eat healthily and exercise
  • Stretching and moving around during a long trip to prevent blood stasis.

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