Pulmonary Embolism

What is a Pulmonary Embolism?

Pulmonary embolism is the medical term for a blood clot that travels to the pulmonary artery.  The condition usually causes the sudden onset of chest pain and difficulty breathing.  It can also cause you to cough up blood.  Pulmonary embolism is a leading cause of death in the United states.

What Causes a Pulmonary Embolism?

Pulmonary embolism is typically caused by a blood clot originating the lower limbs called deep vein thrombosis.  These blood clots can dislodge and travel to the lung – producing symptoms such as sudden chest pain and shortness of breath.  People also frequently develop low oxygen levels (hypoxia) because they cannot effectively exchange gases in the lungs.

The most common risk factors for the development of pulmonary embolism include:

  • Prior history of deep vein thrombosis or pulmonary embolism
  • Prolonged immobility
  • Recent hip surgery
  • Cancer
  • Genetic defects – prothrombin mutation, anti-thrombin deficiency, factor V–Leiden, protein C & S deficiency
  • Certain medications – oral contraceptives, estrogen/progesterone therapy

Prolonged immobility can happen in situations such as recent hip surgery or prolonged flights or car rides.  It is usually recommended that individuals on flights take frequent breaks from sitting to prevent pooling of blood in the lower limbs and clot formation.  Massaging and stretching the legs can also be beneficial in preventing blood clots from forming.

Prolonged immobility may also occur in the elderly, patients with severe joint pain and arthritis, individuals with para- or quadriplegia (e.g., spinal cord injury).  Any individual who is wheelchair dependent is at increased risk for deep vein thrombosis and DVT.

Complications of pulmonary embolism may include:

  • Life-threatening arrhythmias – abnormal heart rhythms
  • Heart failure
  • Hypoxia (low oxygen levels)
  • Death

How Common is a Pulmonary Embolism?

Pulmonary embolism is a common condition that is frequently evaluated in the emergency department.  It is a leading cause of death in the United States - it accounts for about 300,000 deaths each year.  The condition commonly affects the elderly and is seen in approximately 1% of people age 75 or older.  The disease usually requires the expertise of a pulmonary or lung specialist.

Signs and Symptoms

The most common symptoms of pulmonary embolism include:

  • Sudden chest pain
  • Difficulty breathing
  • Coughing up blood (hemoptysis)
  • Wheezing

The pain can worsen on deep breathing or inspiration – a phenomenon called pleuritic chest pain.  Patients with pulmonary emboli typically have elevated heart rates (tachycardia) and low oxygen levels (hypoxia).  Large pulmonary emboli can cause heart failure and sudden death.

Patients frequently have evidence of a deep vein thrombosis such as swelling, pain, warmth, and redness in one leg.


If your doctor suspects pulmonary embolism based on symptoms and signs, they may call 911 and direct you to the nearest emergency department for further evaluation.  This is a medical emergency that typically requires hospitalization.

In the hospital, they will order an EKG (electrocardiogram) and ultrasound of the heart (echocardiogram) to evaluate the heart’s function and structure.  One of the most commonly used studies to confirm a pulmonary embolism is called a CT angiography – a CT scan evaluating for interruptions of blood flow to the lungs.  Occasionally, your doctor will order a study called a V/Q scan, which looks for ventilation and perfusion abnormalities in the lung.

Your doctor will also likely order blood tests such as an arterial blood gas, CMP (comprehensive metabolic panel), CBC (complete blood cell count), and coagulation studies (PT/INR, PTT).  If they think you could have systemic lupus erythematosus they will typically order an antinuclear antibody (ANA) and anti-double-stranded DNA antibody (anti-DS DNA).

Your doctor will also usually evaluate for genetic disorders that lead to blood clot formation.  These include:

  • Factor V Leiden
  • Anti-thrombin deficiency
  • Protein C and S deficiency
  • APC resistance
  • Prothrombin mutation

They may also perform age-appropriate cancer screening.  This may include a prostate- specific antigen (PSA) for prostate cancer in men and a Papaniculaou (PAP) smear for cervical cancer in women.  Additional recommendations may include a colonoscopy if you have risk factors such as family history or age over 50 years.  Breast cancer screening in women is also an important consideration.

Pulmonary Embolism Medication and Treatment

Pulmonary embolism is treated as a medical emergency.  If you have signs of heart strain or failure, you doctor will likely prescribe a medication called a thrombolytic.  Thrombolytics (e.g., tissue plasminogen activator) are a class of drugs that work by rapidly breaking down blood clots and opening-up blood vessels.  In the case of pulmonary embolism, these drugs are injected into the vein to break up venous clots.  These medications may also be injected into arteries in patients arterial clots causing heart attack or stroke.

Some cases may benefit from interventional techniques such as catheter embolectomy and fragmentation or surgical embolectomy.

If you have no signs of heart strain or failure, you doctor will most likely start you on either one of these blood thinner medications: heparin or Lovenox (Enoxaparin).

If you and your doctor determine the benefits of oral anticoagulation outweigh its risks, they may prescribe a long-term oral blood thinner called Coumadin (Warfarin).

Warfarin interacts with a host of medications and foods (e.g., spinach).  This medication also needs to be monitored very closely with regular blood tests – therefore, a lot of patients are started on newer oral anticoagulants such as:


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  2. Heit JA1. Epidemiology of venous thromboembolism. Nat Rev Cardiol. 2015 Aug;12(8):464-74. - https://www.ncbi.nlm.nih.gov/pubmed/26076949
  3. Segal JB1, Streiff MB, Hofmann LV. Management of venous thromboembolism: a systematic review for a practice guideline. Ann Intern Med. 2007 Feb 6;146(3):211-22. - https://www.ncbi.nlm.nih.gov/pubmed/17261856

Pulmonary Embolism Medication

The above information is an educational aid only. It is not intended as medical advice for individual conditions or treatments. Talk to your doctor, nurse or pharmacist before following any medical regimen to see if it is safe and effective for you.