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Pulmonary Embolism: Difference between revisions
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Tests that are frequently done that are not sensitive for PE, but can be diagnostic. | Tests that are frequently done that are not sensitive for PE, but can be diagnostic. | ||
*''Chest X-rays'' are often done on patients with shortness of breath to help rule-out other causes, such as congestive heart failure and rib fracture. Chest X-rays in PE are rarely normal, <cite>REFNAME20</cite> but usually lack signs that suggest the diagnosis of PE (e.g. Westermark sign, Hampton's hump). | *''Chest X-rays'' are often done on patients with shortness of breath to help rule-out other causes, such as congestive heart failure and rib fracture. Chest X-rays in PE are rarely normal, <cite>REFNAME20</cite> but usually lack signs that suggest the diagnosis of PE (e.g. Westermark sign, Hampton's hump). | ||
*''Ultrasonography of the legs'', also known as ''leg doppler'', in search of deep venous thrombosis (DVT). The presence of DVT, as shown on ultrasonography of the legs, is in itself enough to warrant anticoagulation, without requiring the V/Q or spiral CT scans (because of the strong association between DVT and PE). This may be valid approach in pregnancy, in which the other modalities would increase the risk of birth defects in the unborn child. However, a negative scan does not rule out PE, and low-radiation dose scanning may be required if the mother is deemed at high risk of having pulmonary embolism. | *''Ultrasonography of the legs'', also known as ''leg doppler'', in search of deep venous thrombosis (DVT). The presence of DVT, as shown on ultrasonography of the legs, is in itself enough to warrant anticoagulation, without requiring the V/Q or spiral CT scans (because of the strong association between DVT and PE). This may be valid approach in pregnancy, in which the other modalities would increase the risk of birth defects in the unborn child. However, a negative scan does not rule out PE, and low-radiation dose scanning may be required if the mother is deemed at high risk of having pulmonary embolism. | ||
===Electrocardiogram=== | ===Electrocardiogram=== | ||
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===Anticoagulation=== | ===Anticoagulation=== | ||
In most cases, anticoagulant therapy is the mainstay of treatment. Heparin, low molecular weight heparins (such as enoxaparin and dalteparin), or fondaparinux is administered initially, while warfarin, acenocoumarol, or phenprocoumon therapy is commenced (this may take several days, usually while the patient is in the hospital). Low molecular weight heparin may reduce bleeding among patients with pulmonary embolism as compared to heparin according to a systematic review of randomized controlled trials by the Cochrane Collaboration. <cite>REFNAME28</cite> The relative risk reduction was 40.0%. For patients at similar risk to those in this study (2.0% had bleeding when not treated with low molecular weight heparin), this leads to an absolute risk reduction of 0.8%. 125.0 patients must be treated for one to benefit. | In most cases, anticoagulant therapy is the mainstay of treatment. Heparin, low molecular weight heparins (such as enoxaparin and dalteparin), or fondaparinux is administered initially, while warfarin, acenocoumarol, or phenprocoumon therapy is commenced (this may take several days, usually while the patient is in the hospital). Low molecular weight heparin may reduce bleeding among patients with pulmonary embolism as compared to heparin according to a systematic review of randomized controlled trials by the Cochrane Collaboration. <cite>REFNAME28</cite> The relative risk reduction was 40.0%. For patients at similar risk to those in this study (2.0% had bleeding when not treated with low molecular weight heparin), this leads to an absolute risk reduction of 0.8%. 125.0 patients must be treated for one to benefit. | ||
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Warfarin therapy often requires frequent dose adjustment and monitoring of the INR. In PE, INRs between 2.0 and 3.0 are generally considered ideal. If another episode of PE occurs under warfarin treatment, the INR window may be increased to e.g. 2.5-3.5 (unless there are contraindications) or anticoagulation may be changed to a different anticoagulant e.g. low molecular weight heparin. In patients with an underlying malignancy, therapy with a course of low molecular weight heparin may be favored over warfarin based on the results of the CLOT trial. <cite>REFNAME30</cite> | Warfarin therapy often requires frequent dose adjustment and monitoring of the INR. In PE, INRs between 2.0 and 3.0 are generally considered ideal. If another episode of PE occurs under warfarin treatment, the INR window may be increased to e.g. 2.5-3.5 (unless there are contraindications) or anticoagulation may be changed to a different anticoagulant e.g. low molecular weight heparin. In patients with an underlying malignancy, therapy with a course of low molecular weight heparin may be favored over warfarin based on the results of the CLOT trial. <cite>REFNAME30</cite> | ||
Similarly, pregnant women are often maintained on low molecular weight heparin to avoid the known teratogenic effects of warfarin, especially in the early stages of pregnancy. | Similarly, pregnant women are often maintained on low molecular weight heparin to avoid the known teratogenic effects of warfarin, especially in the early stages of pregnancy. | ||
People are usually admitted to hospital in the early stages of treatment, and tend to remain under inpatient care until INR has reached therapeutic levels. Increasingly, low-risk cases are managed on an outpatient basis in a fashion already common in the treatment of DVT. <cite>REFNAME31</cite> | People are usually admitted to hospital in the early stages of treatment, and tend to remain under inpatient care until INR has reached therapeutic levels. Increasingly, low-risk cases are managed on an outpatient basis in a fashion already common in the treatment of DVT. <cite>REFNAME31</cite> | ||
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===Thrombolysis=== | ===Thrombolysis=== | ||
Massive PE causing hemodynamic instability (shock and/or hypotension, defined as a systolic blood pressure <90 mmHg or a pressure drop of 40 mmHg for>15 min if not caused by new-onset arrhythmia, hypovolemia or sepsis) is an indication for thrombolysis, the enzymatic destruction of the clot with medication. It is the best available medical treatment in this situation and is supported by clinical guidelines. <cite>REFNAME33</cite> <cite>ESC</cite> <cite>REFNAME34</cite> | Massive PE causing hemodynamic instability (shock and/or hypotension, defined as a systolic blood pressure <90 mmHg or a pressure drop of 40 mmHg for>15 min if not caused by new-onset arrhythmia, hypovolemia or sepsis) is an indication for thrombolysis, the enzymatic destruction of the clot with medication. It is the best available medical treatment in this situation and is supported by clinical guidelines. <cite>REFNAME33</cite> <cite>ESC</cite> <cite>REFNAME34</cite> | ||
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===Inferior vena cava filter=== | ===Inferior vena cava filter=== | ||
If anticoagulant therapy is contraindicated and/or ineffective, or to prevent new emboli from entering the pulmonary artery and combining with an existing blockage, an inferior vena cava filter may be implanted. <cite>REFNAME38</cite> | If anticoagulant therapy is contraindicated and/or ineffective, or to prevent new emboli from entering the pulmonary artery and combining with an existing blockage, an inferior vena cava filter may be implanted. <cite>REFNAME38</cite> | ||
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===Underlying causes=== | ===Underlying causes=== | ||
After a first PE, the search for secondary causes is usually brief. Only when a second PE occurs, and especially when this happens while still under anticoagulant therapy, a further search for underlying conditions is undertaken. This will include testing ("thrombophilia screen") for Factor V Leiden mutation, antiphospholipid antibodies, protein C and S and antithrombin levels, and later prothrombin mutation, MTHFR mutation, Factor VIII concentration and rarer inherited coagulation abnormalities. | After a first PE, the search for secondary causes is usually brief. Only when a second PE occurs, and especially when this happens while still under anticoagulant therapy, a further search for underlying conditions is undertaken. This will include testing ("thrombophilia screen") for Factor V Leiden mutation, antiphospholipid antibodies, protein C and S and antithrombin levels, and later prothrombin mutation, MTHFR mutation, Factor VIII concentration and rarer inherited coagulation abnormalities. | ||
==References== | ==References== | ||