The passage of an embolus (an abnormally circulating body in the blood) into the arteries to the lungs. The most common source is a blood clot (thrombus) originating from an area of thrombosis in the leg. It may lodge in the main pulmonary artery, completely obstructing the flow of blood to the lungs and resulting in sudden death. Smaller clots block blood flow to smaller segments of lung tissue and give rise to symptoms including shortness of breath, chest pain, and haemoptysis.
Pulmonary embolismClassifications and external resources
| ICD-10 | I26.0, I26.9 |
|---|---|
| ICD-9 | 415.1 |
| DiseasesDB | 10956 |
| MedlinePlus | 000132 |
| eMedicine | med/1958 |
Pulmonary embolism is a blockage of an artery in the lungs by a blood clot, fat, air or clumped tumor cells. By far the most common form of pulmonary embolism is a thromboembolism, which occurs when a blood clot, generally a venous thrombus, becomes dislodged from its site of formation and embolizes to the arterial blood supply of one of the lungs. Other rarer forms of pulmonary embolism occur when material other than a blood clot is responsible.
Signs, symptoms and risk factors
Clinical presentation
Signs of PE are sudden-onset dyspnea (shortness of breath, 73%), tachypnea (rapid breathing, 70%), chest pain of "pleuritic" nature (worsened by breathing, 66%), cough (37%), hemoptysis (coughing up blood, 13%), and in severe cases, cyanosis, tachycardia (rapid heart rate), hypotension, shock, loss of consciousness, and death.
Risk factors
The most common sources of embolism are proximal leg deep venous thrombosis (DVTs) or pelvic vein thromboses. Any risk factor for DVT also increases the risk that the venous clot will dislodge and migrate to the lung circulation, which happens in up to 15% of all DVTs.
Risk factors for DVT and PE (together "venous thromboembolism" or VTE) can be divided into genetic, acquired and circumstantial causes. Acquired Antiphospholipid antibodies Anticardiolipin antibodies and/or lupus anticoagulants Renal disease (renal loss of antithrombin) Paroxysmal nocturnal hemoglobinuria Circumstantial Immobilisation, e.g., after surgery or trauma Use of oral contraceptives Obesity Pregnancy Cancer ( as in Trousseau's syndrome)
Diagnosis
The gold standard for diagnosing pulmonary embolism (PE) is pulmonary angiography.
Computed tomography with radiocontrast, effectively a pulmonary angiogram imaged by CT and known as CT Pulmonary Angiography (CTPA), is increasingly used as the mainstay in diagnosis. Advantages are clinical equivalence, better access for patients and the possibility of picking up other lung disorders from the differential diagnosis in case there is no pulmonary embolism.In low/moderate suspicion of PE, a normal D-dimer level (shown in a blood test) is enough to exclude the possibility of PE.
An electrocardiogram may show signs of right heart strain or acute cor pulmonale in cases of large PEs - the classic signs are a large S wave in lead I, a large Q wave in lead III and an inverted T wave in lead III ("S1Q3T3").
In massive PE, dysfunction of the right side of the heart can be seen on echocardiography (EKG), an indication that the pulmonary artery is severely obstructed and the heart is unable to match the pressure.
The presence of deep venous thrombosis is in itself enough to warrant anticoagulation, without requiring the V/Q or spiral CT scans, and leg ultrasound can be used as a surrogate. 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.
Further analysis
When a PE is being suspected, a number of blood tests are also done, in order to exclude important secondary causes of PE.
Treatment
Acutely, supportive treatments, such as oxygen or analgesia, are often required.
Massive PE causing hemodynamic instability (marked decreased oxygen saturation, tachycardia and/or hypotension) is an indication for thrombolysis, the enzymatic destruction of the clot with medication.
Medical management
In most cases, anticoagulant therapy is the mainstay of treatment.
Thrombolysis
Thrombolysis can be given for severe PEs when surgery is not immediately available or possible (e.g.
Tissue plasminogen activator (tPA): 100mg IV over 2 hours then IV heparin for 48 hours aiming to keep the APTT ratio between .
Streptokinase 250 000 units IV over an hour, followed by 100 000 units IV per hour for 24 hours.
Surgical management of PE
Acute
Surgical management of acute pulmonary embolism (pulmonary thrombectomy) is uncommon and has largely been abandoned because of poor long-term outcomes.
Chronic
Chronic pulmonary embolism leading to pulmonary hypertension (known as chronic thromboembolic hypertension) is treated with a surgical procedure known as a pulmonary thromboendarterectomy.
Prognosis
Mortality from untreated PE is said to be 26%. This study is the only placebo controlled trial ever to examine the place of anticoagulants in the treatment of PE, the results of which were so convincing that the trial has never been repeated as to do so would be considered unethical.
Prognosis depends on the amount of lung that is affected and on the co-existence of other debilitating conditions;
After a first PE, the search for secondary causes is usually brief.
History
Notable victims of pulmonary embolism are William II, the last Kaiser of Germany, and NBC television reporter David Bloom, while traveling with American troops in Iraq.
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