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An estimated 50,000 to 200,000 Americans die from pulmonary embolism each year.
Risk factors:
Inherited: antithrombin III deficiency, protein C deficiency, protein S deficiency, dysfibrogenemia, and disorders of plasminogen and plasminogen activation.
Acquired: Surgery, age, fracture/trauma, malignancy, neuromuscular
disorders.
Diagnosis:
Clinical: notoriously unreliable. (sensitivity 30%)
Venography: gold standard--- exception: the profunda femoris and the internal iliac veins.
IPG: 95% sensitive and specific for proximal DVT.
Doppler
Duplex
Radiofibrinogen: effective for calf DVT. (sensitivity 90%)
Pulmonary embolism
Diagnosis: V/Q scan: false (+) in 20-48% of cases. pulmonary angiogram:detect
emboli up to a diameter of 2.5 mm, gold standard.
Calf DVT
Controversial over the need to treat.
--- Patients with PE have calf-only DVT 5% of the time.
--- A progression to a proximal thrombus in 25 % of postoperative calf thrombi. Direct embolization also exists.
--- The calf-only thrombi not detected by serial IPG (day 1, 3,
5, 7, 10, 14) do not seem to cause clinically overt symptoms if
untreated in patients who have lower extremity symptoms compatible
with a diagnosis of venous thrombosis. (Hull RD et al.: Diagnostic
efficacy of impedance plethysmography for clinically suspected
deep-vein thrombosis. A randomized trial. Annals of internal medicine.
1985; 102:21-28)
--- Lagerstedt CI et al.: in a randomized study of 51 patients (23 received warfarin for 3 months and 28 did not). Both groups received an initial course of heparin. During the first 3 months, 8 patients in the non-warfarin group had recurrences compared with none in the warfarin group. They suggested that oral anticoagulants should be given to all patients with thrombi that produce symptoms. (Need for long-term anticoagulant treatment in symptomatic calf-vein thrombosis. Lancet: 2:515-518, 1985.)
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