Pulmonary Embolism (cont.)
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.
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.
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.
In this Article
- Pulmonary embolism facts
- What is a pulmonary embolism?
- What are the causes and risk factors for pulmonary embolism?
- What are the signs and symptoms of pulmonary embolism?
- How is pulmonary embolism diagnosed?
- PERC Rule for Pulmonary Embolus
- Basic testing (CBC, electrolytes, BUN, creatinine blood test, chest X-ray, EKG)
- Pulmonary angiogram
- d-Dimer blood test
- CT scan
- Ventilation-perfusion scans
- Venous Doppler study
- What is the treatment for pulmonary embolism?
- Thrombolytic therapy
- What is the prognosis for pulmonary embolism?
- Can pulmonary embolism be prevented?
Anticoagulation prevents further growth of the blood clot and preventing more lung tissue from being affected. The body has complex mechanism to form blood clots to help repair blood vessel damage. Under normal conditions, there is a clotting cascade with numerous blood factors that have to be activated for a clot to form.
Medications are available that block the clotting cascade at different places and therefore "thin" or anti-coagulate the blood.
Warfarin (Coumadin) is the classic anti-coagulation medication that acts as a Vitamin K antagonist, blocking blood clotting factors II, VII, IX and X. It is prescribed immediately after diagnosis of a clot or pulmonary embolism, but unfortunately may it take a week or more for the blood to be appropriately thinned. Therefore, low molecular weight heparin (enoxaparin [Lovenox]) is administered at the same time. It thins the blood via a different mechanism and is used as a bridge therapy until the warfarin has reached its therapeutic level. Enoxaparin injections can be given on an outpatient basis. For those patients who have contraindications to the use of enoxaparin (for example, kidney failure does not allow enoxaparin to be appropriately metabolized), intravenous heparin can be used as the first step in association with warfarin. This requires admission to the hospital.
The dosage of warfarin is monitored by blood tests measuring the prothrombin time or INR (international normalized ratio). Therapeutic levels range from 2.0 - 3.0.
Newer anticoagulation medications as treatment options for pulmonary embolus inhibit blood factor X. These act almost immediately to thin the blood and do not need the two step approach of warfarin and heparin. Medications that have been approved for pulmonary embolus treatment include:
- apixaban (Eliquis),
- rivaroxaban (Xarelto),
- dabigatran (Pradaxa) and
- edoxaban (Savaysa).
These medications do not need blood tests to monitor dosing.
The decision to prescribe a type of anticoagulation medication (Vitamin K antagonist v. Factor X inhibitor) depends upon the patient situation. Patients who take any of these medications are at risk for bleeding. At present there is no antidote approved in the United States to reverse the effects of the Factor X inhibitors, should the need arise. There are reversal strategies available for warfarin and heparin.
The recommended length of treatment for an uncomplicated pulmonary embolism is 3 months. Depending upon the patient situation, a longer duration of anticoagulation may be required.
Next: Thrombolytic therapy
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