Pulmonary Embolism (Blood Clot in the Lung)

  • Medical Author:
    Benjamin Wedro, MD, FACEP, FAAEM

    Dr. Ben Wedro practices emergency medicine at Gundersen Clinic, a regional trauma center in La Crosse, Wisconsin. His background includes undergraduate and medical studies at the University of Alberta, a Family Practice internship at Queen's University in Kingston, Ontario and residency training in Emergency Medicine at the University of Oklahoma Health Sciences Center.

  • Medical Editor: George Schiffman, MD, FCCP
    George Schiffman, MD, FCCP

    George Schiffman, MD, FCCP

    Dr. Schiffman received his B.S. degree with High Honors in biology from Hobart College in 1976. He then moved to Chicago where he studied biochemistry at the University of Illinois, Chicago Circle. He attended Rush Medical College where he received his M.D. degree in 1982 and was elected to the Alpha Omega Alpha Medical Honor Society. He completed his Internal Medicine internship and residency at the University of California, Irvine.

  • Medical Editor: Melissa Conrad Stöppler, MD
    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

Quick GuideDVT in Pictures: Symptoms of Deep Vein Thrombosis, Beyond Leg Pain and More

DVT in Pictures: Symptoms of Deep Vein Thrombosis, Beyond Leg Pain and More

Thrombolytic therapy

Pulmonary embolism can be fatal, especially if there is a large amount of clot present within the pulmonary arteries. Tissue plasminogen activator (tPA) is a medication given to break up blood clots, known as thrombolytic therapy. Thrombolytic therapy with tPA is indicated in patients with pulmonary emboli who also have hypotension (low blood pressure), since this may be one sign of shock. Others signs of shock include:

  • confusion,
  • coma, or
  • damage to other organs including the heart and kidneys.

tPA helps break up or dissolve the arterial clot. It may be given peripherally in an IV or centrally, through a catheter that is inserted in the arm or groin and threaded into the pulmonary artery, so that the medication can be delivered directly to the clot. Evidence of right heart strain on CT scan or by echocardiogram, or blood tests that show the heart to be under strain (for example, troponin levels), also may be an indication for thrombolytic therapy, depending upon the clinical situation.

Thrombolytic therapy with tPA is an emergent treatment that thins the blood immediately. Warfarin and factor X inhibitors are not prescribed immediately in this situation, though unfractionated heparin may be used initially while decisions regarding the use of tPA are considered.

What is the prognosis for pulmonary embolism?

Patient survival depends upon:

  • the underlying health of the patient,
  • size of the pulmonary embolus,
  • the cause of the pulmonary embolus, and
  • the ability for a diagnosis to be made and treatment initiated.

The diagnosis is often difficult, and it is estimated to that there are up to 400,000 cases of pulmonary embolus that are not diagnosed in the United States each year.

In those patients where the diagnosis is made, the death (mortality) rate is less than 20% when considering all patients. Usually, however, the mortality risk is much less in most patients. The higher incidence of death occurs in patients that are older, have other underlying illnesses, or have a delay in diagnosis. Racial differences may also exist, but probably are due more to access to quality care than a specific genetic difference.

Can pulmonary embolism be prevented?

Minimizing the risk of deep vein thrombosis minimizes the risk of pulmonary embolism. The embolism cannot occur without the initial DVT.

  • In the hospital setting, the nursing staff works hard to minimize the potential for clot formation in immobilized patients. Compression stockings are routinely used. Surgery patients are out of bed walking (ambulatory) earlier and low dose heparin or enoxaparin is being used for deep vein thrombosis prophylaxis (measures taken to prevent deep vein thrombosis).
  • For those who travel, it is recommended that they get up and walk every couple of hours during a long trip.
  • Compression stockings may be helpful in preventing future deep vein thrombus formation in patients with a previous history of a clot.
  • Smoking is a risk factor for DVT formation, especially in women who are on the birth control pill.


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Carman, tl, Gegaj F Management of Pulmonary Embolism: 2010 State of the Art Update Curr Treat Options. Cardiovasc Med. 2010 Apr;12(2);168-184

Giancarlo, A., et al. "Apixaban for Extended Treatment of Venous Thromboembolism." New England Journal of Medicine. 368 (2013): 699-708.

Kline, JA et al. Prospective multicenter evaluation of the pulmonary embolus rule-out criteria. J Thromb Haemost. 2008 May, 6(5).

Pollack, C.V., et al. "Idarucizumab for Dabigatran Reversal." New England Journal of Medicine. 373.6 (2015): 511-520.

Tintinalli J, etal. Tintinalli's Emergency Medicine: A Comprehensive Study Guide. 7th edition. McGraw-Hill Professional 2010.

Medically Reviewed by a Doctor on 11/20/2015

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