Questions and Answers
Which of the following best describes the typical effects of smaller thrombi in the lung?
Which factor is NOT part of Virchow's triad that contributes to thrombosis in deep veins?
What is the clinical presentation characteristic of acute massive pulmonary embolism?
Which presentation is commonly associated with pulmonary infarction?
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What is a potential outcome of chronic pulmonary embolism?
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Which statement about gas exchange in the lungs during pulmonary embolism is correct?
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Which of the following is NOT a typical complication associated with pulmonary embolism?
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Identify the condition that can lead to vessel wall injury, contributing to thrombosis.
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What condition leads to areas of low ventilation to perfusion ratios in the lungs?
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How do elevated right atrial pressures influence shunting during an acute pulmonary embolism?
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Which classification of pulmonary embolism indicates hemodynamic instability?
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What is the most likely outcome if a D-dimer test is negative in a patient with low pretest probability of VTE?
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Which imaging technique is considered the gold standard for diagnosing pulmonary embolism?
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What is a common finding on a chest X-ray for someone with pulmonary embolism?
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What occurs to the left ventricular cardiac output due to right ventricular overload in pulmonary embolism?
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Which laboratory test is typically elevated in patients with acute thrombotic disorders?
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What is the primary cause of most pulmonary embolism cases?
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Which of the following is a source of emboli that is least commonly associated with pulmonary embolism?
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Which type of thrombus poses a minimal embolic risk?
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Which of the following conditions is most likely to lead to an embolus from pelvic veins?
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What is the most common source of acute symptomatic pulmonary embolism?
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Which type of embolus can arise from the right side of the heart?
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What process describes the obstruction of the pulmonary artery due to a traveled substance?
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After lodging in the lung, what can large thrombi cause?
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What is a primary limitation of using MRI for diagnosing pulmonary embolism (PE)?
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Which of the following is NOT an advantage of V/Q scans over CT scans?
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What does a V/Q scan primarily detect?
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Which of the following ECG findings is commonly associated with a large pulmonary embolism?
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When initiating warfarin therapy after heparin, what is the recommended starting dose?
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What is the target INR range for anticoagulation in venous thromboembolism?
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Which of the following statements regarding low molecular weight heparin (LMWH) is false?
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Which blood gas change typically accompanies hyperventilation due to a pulmonary embolism?
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What is a major advantage of NOACs over VKAs?
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In which situation is an inferior vena cava (IVC) filter indicated?
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What is the primary purpose of thrombolytic therapy?
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What defines chronic thromboembolic pulmonary hypertension (CTEPH)?
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What measurement indicates pulmonary arterial hypertension (PAH)?
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Which option describes the definition of cor pulmonale?
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What is a characteristic of Group 2 pulmonary hypertension?
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Which of the following is NOT a reason to perform surgical embolectomy?
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Study Notes
Definition and Causes of Pulmonary Embolism
- Pulmonary embolism (PE) is the obstruction of the pulmonary artery or its branches by an embolus, often originating from deep vein thrombosis (DVT).
- Venous thromboembolism (VTE) leads to PE when a blood clot from limbs travels to the lungs.
- Other embolic sources include:
- Fat: released from bone marrow due to fractures or burns.
- Tumor fragments: can break off from cancerous growths.
- Air bubbles: may enter the bloodstream during medical procedures or resuscitation efforts.
- Amniotic fluid: can enter the circulation during childbirth.
- Talc: associated with intravenous drug use.
Sources of Emboli and Risk Factors
- 80-95% of VTE cases stem from thrombi in the lower extremities, especially the calf veins.
- Thrombi that extend above the popliteal vein have a higher risk of causing acute PE.
- Other possible embolic sources include pelvic veins (affected by pregnancy or surgery), upper extremities (via central venous catheters), and the right heart (mural thrombi or vegetations).
- Key risk factors for DVT and PE include:
- Stasis: due to immobility or age.
- Hypercoagulability: due to obesity, pregnancy, malignancy, and surgery.
- Vessel wall injury: caused by inflammation or trauma.
Clinical Presentation of PE
- Acute Massive PE: sudden severe chest pain, dyspnea, cardiogenic shock symptoms like hypotension and tachycardia, potential for sudden death.
- Pulmonary Infarction: localized pleuritic chest pain, hemoptysis, fever, possible pleural rub or effusion.
- Small PE: may cause reflex hyperventilation without significant symptoms.
- Chronic PE: recurrent emboli leading to pulmonary hypertension and cor pulmonale indicated by exertional dyspnea and RV dysfunction.
Physiology and Pathophysiology
- PE disrupts gas exchange, leading to hypoxemia, predominantly caused by ventilation-perfusion mismatches.
- Increased dead space in alveoli reduces effective gas exchange.
- Hemodynamic impact: right ventricular overload diminishes left ventricular output, risking cardiac compromise.
Classification of PE Severity
- Non-massive PE: normotensive patients with normal RV function.
- Massive PE: hemodynamic instability from RV failure.
- Sub-massive PE: normotensive with RV dysfunction evident on imaging.
Diagnosis of PE
- Diagnosis integrates clinical findings with laboratory tests (e.g., D-dimer) and imaging like CT pulmonary angiography.
- Wells scoring system helps assess PE probability; scores above 4 warrant further diagnostic imaging.
Investigations
- D-Dimer: sensitive for acute thrombotic disorders, negative results can aid in ruling out VTE.
- Imaging options include:
- Chest X-ray: can show indirect signs of PE.
- CT pulmonary angiography: first-line, visualizes thrombi directly.
- Ventilation/perfusion (V/Q) scan: evaluates mismatches due to obstruction; safer for certain patients compared to CT.
- Echocardiography: assess right heart size and function.
PE Prophylaxis and Treatment
- Prophylaxis for moderate to high-risk patients includes low-dose heparin.
- Anticoagulant therapy: unfractionated heparin or low molecular weight heparin initiates therapy, followed by warfarin for long-term management (target INR of 2-3).
- Thrombolytic therapy: indicated in massive PE with hemodynamic instability.
- Inferior vena cava (IVC) filters: employed for patients who cannot tolerate anticoagulation.
- Surgical options include embolectomy and pulmonary thromboendarterectomy for chronic cases.
Pulmonary Hypertension & Cor Pulmonale
- Defined as mean pulmonary artery pressure >20 mm Hg; classified into five main groups based on underlying causes.
- Cor pulmonale arises from chronic respiratory disorders causing RV dysfunction.
- Chronic respiratory diseases associated include COPD and pulmonary thromboembolic disease.
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Description
This quiz explores the definition and causes of pulmonary embolism (PE), detailing its link to venous thromboembolism (VTE). Participants will learn about various sources of emboli, such as fat, tumor fragments, and air bubbles, as well as crucial risk factors for developing PE. Test your knowledge on this critical topic in vascular health.