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Emergency And Acute Medicine – Pulmonary Embolism
Pulmonary embolism (PE) occurs when thrombi—most commonly originating in the deep veins of the lower extremities or pelvis—travel to and obstruct the pulmonary arterial circulation. Thrombi may also arise from renal or upper extremity veins. The size and location of the embolus determine the severity of clinical manifestations, ranging from mild dyspnea to cardiovascular collapse.
Most patients with PE have identifiable risk factors. Common acquired risks include recent surgery, immobilization, pregnancy, prior DVT or PE, stroke or paraplegia, malignancy, age over 50 years, obesity, smoking, oral contraceptive use, and major trauma. Inherited thrombophilias include Factor V Leiden mutation, protein C or S deficiency, antithrombin III deficiency, antiphospholipid antibody syndrome, and lupus anticoagulant. In children, PE is rare and usually associated with central venous catheters, immobility, congenital heart disease, trauma, malignancy, surgery, or infection.
Clinical presentation is variable and often nonspecific. The most common symptoms are dyspnea, pleuritic chest pain, and tachypnea. Patients may also report cough or hemoptysis (rarely massive). Cardiovascular findings can include tachycardia, syncope, or hypotension in massive PE. Fever is uncommon and usually low grade. Physical exam may reveal cyanosis, signs of DVT (unilateral leg swelling, tenderness), or evidence of thrombophlebitis. In elderly patients, symptoms may be subtle.
Initial evaluation includes chest radiography and ECG primarily to rule out alternative diagnoses. Chest x-ray is often normal in PE but may show nonspecific findings such as atelectasis or pleural effusion. Classic but uncommon signs include Hampton hump (pleural-based opacity) and Westermark sign (regional oligemia). ECG is usually normal or shows sinus tachycardia. Other possible findings include nonspecific ST–T changes, right bundle branch block, or S1Q3T3 pattern (neither sensitive nor specific).
Risk stratification tools assist in diagnostic decision-making. The modified Wells criteria assign points based on clinical features such as signs of DVT, heart rate >100 bpm, recent surgery or immobilization, prior DVT/PE, hemoptysis, malignancy, and whether PE is the most likely diagnosis. A score <4 combined with a negative d-dimer confers <2% risk of pe. the pulmonary embolism rule-out criteria (perc) may exclude pe in low-risk patients if all are (age <50, hr <100, o₂ saturation ≥95%, no hemoptysis, estrogen use, prior dvt />E, no unilateral leg swelling, no recent surgery/trauma). A PERC-negative patient with low clinical suspicion has <1% risk of pe within 45 days.< />pan>
Laboratory studies are nonspecific. Arterial blood gas may show hypoxemia, hypocapnia, respiratory alkalosis, or elevated alveolar–arterial gradient, but can be normal. CBC may reveal anemia. D-dimer testing (enzyme-linked immunosorbent assay) has high sensitivity but low specificity; a negative d-dimer in a low-risk patient effectively rules out PE. D-dimer is frequently elevated in malignancy or recent surgery.
Imaging is central to diagnosis. CT pulmonary angiography (CTPA) is the preferred diagnostic modality and can also detect alternative causes of symptoms. It is highly accurate for proximal emboli, with positive and negative predictive values around 96% in appropriate pretest probability groups. Ventilation–perfusion (V/Q) scanning remains useful, particularly in patients with contraindications to contrast. A normal V/Q scan effectively excludes PE, whereas a high-probability V/Q scan combined with high clinical suspicion confers approximately 96% probability of PE. Lower-extremity duplex ultrasound may identify DVT; a positive study supports anticoagulation, though a negative result does not exclude PE. Echocardiography assesses right ventricular strain and may guide management in unstable patients. Pulmonary angiography remains the gold standard but is reserved for cases where noninvasive imaging is inconclusive.
Management begins with airway, breathing, and circulation. Supplemental oxygen, IV access, and cardiac monitoring are initiated. In hypotensive patients, IV fluids should be administered cautiously, as excessive volume may worsen right ventricular failure. Vasopressors may be required if hypotension persists.
Anticoagulation is the cornerstone of treatment, preventing further clot formation and stabilizing existing thrombus. Unfractionated heparin requires close monitoring with target activated partial thromboplastin time 1.5–2.5 times control. Low-molecular-weight heparin (e.g., enoxaparin 1 mg/kg SC every 12 hours) is at least as effective and easier to administer. Long-term therapy includes warfarin (target INR 2–3) or direct oral anticoagulants such as rivaroxaban (15 mg twice daily for 3 weeks, then 20 mg daily). Rivaroxaban does not require routine monitoring but is not recommended in renal or hepatic insufficiency or pregnancy.
Thrombolysis (e.g., alteplase 100 mg IV over 2 hours) is indicated in hemodynamically unstable patients with confirmed PE and may be considered in selected stable patients with massive PE, severe hypoxemia, or right ventricular dysfunction. Inferior vena cava filters are reserved for patients with contraindications to anticoagulation or recurrent PE despite therapeutic anticoagulation. Surgical or catheter-directed embolectomy may be considered in select unstable patients.
All patients diagnosed with PE require hospital admission for monitoring and anticoagulation. In selected stable patients with high suspicion and no contraindications, empiric anticoagulation may be started while awaiting definitive imaging if diagnostic resources are temporarily unavailable.
The clinical presentation of PE is highly variable and often mimics other conditions such as myocardial infarction, pneumonia, asthma, pneumothorax, or anxiety. Maintaining a high index of suspicion is essential. Patients with malignancy are at increased risk of recurrent PE despite therapeutic anticoagulation. Early risk stratification and prompt treatment significantly reduce morbidity and mortality.
Pulmonary embolism (PE) occurs when thrombi—most commonly originating in the deep veins of the lower extremities or pelvis—travel to and obstruct the pulmonary arterial circulation. Thrombi may also arise from renal or upper extremity veins. The size and location of the embolus determine the severity of clinical manifestations, ranging from mild dyspnea to cardiovascular collapse.
Most patients with PE have identifiable risk factors. Common acquired risks include recent surgery, immobilization, pregnancy, prior DVT or PE, stroke or paraplegia, malignancy, age over 50 years, obesity, smoking, oral contraceptive use, and major trauma. Inherited thrombophilias include Factor V Leiden mutation, protein C or S deficiency, antithrombin III deficiency, antiphospholipid antibody syndrome, and lupus anticoagulant. In children, PE is rare and usually associated with central venous catheters, immobility, congenital heart disease, trauma, malignancy, surgery, or infection.
Clinical presentation is variable and often nonspecific. The most common symptoms are dyspnea, pleuritic chest pain, and tachypnea. Patients may also report cough or hemoptysis (rarely massive). Cardiovascular findings can include tachycardia, syncope, or hypotension in massive PE. Fever is uncommon and usually low grade. Physical exam may reveal cyanosis, signs of DVT (unilateral leg swelling, tenderness), or evidence of thrombophlebitis. In elderly patients, symptoms may be subtle.
Initial evaluation includes chest radiography and ECG primarily to rule out alternative diagnoses. Chest x-ray is often normal in PE but may show nonspecific findings such as atelectasis or pleural effusion. Classic but uncommon signs include Hampton hump (pleural-based opacity) and Westermark sign (regional oligemia). ECG is usually normal or shows sinus tachycardia. Other possible findings include nonspecific ST–T changes, right bundle branch block, or S1Q3T3 pattern (neither sensitive nor specific).
Risk stratification tools assist in diagnostic decision-making. The modified Wells criteria assign points based on clinical features such as signs of DVT, heart rate >100 bpm, recent surgery or immobilization, prior DVT/PE, hemoptysis, malignancy, and whether PE is the most likely diagnosis. A score <4 combined with a negative d-dimer confers <2% risk of pe. the pulmonary embolism rule-out criteria (perc) may exclude pe in low-risk patients if all are (age <50, hr <100, o₂ saturation ≥95%, no hemoptysis, estrogen use, prior dvt />E, no unilateral leg swelling, no recent surgery/trauma). A PERC-negative patient with low clinical suspicion has <1% risk of pe within 45 days.< />pan>
Laboratory studies are nonspecific. Arterial blood gas may show hypoxemia, hypocapnia, respiratory alkalosis, or elevated alveolar–arterial gradient, but can be normal. CBC may reveal anemia. D-dimer testing (enzyme-linked immunosorbent assay) has high sensitivity but low specificity; a negative d-dimer in a low-risk patient effectively rules out PE. D-dimer is frequently elevated in malignancy or recent surgery.
Imaging is central to diagnosis. CT pulmonary angiography (CTPA) is the preferred diagnostic modality and can also detect alternative causes of symptoms. It is highly accurate for proximal emboli, with positive and negative predictive values around 96% in appropriate pretest probability groups. Ventilation–perfusion (V/Q) scanning remains useful, particularly in patients with contraindications to contrast. A normal V/Q scan effectively excludes PE, whereas a high-probability V/Q scan combined with high clinical suspicion confers approximately 96% probability of PE. Lower-extremity duplex ultrasound may identify DVT; a positive study supports anticoagulation, though a negative result does not exclude PE. Echocardiography assesses right ventricular strain and may guide management in unstable patients. Pulmonary angiography remains the gold standard but is reserved for cases where noninvasive imaging is inconclusive.
Management begins with airway, breathing, and circulation. Supplemental oxygen, IV access, and cardiac monitoring are initiated. In hypotensive patients, IV fluids should be administered cautiously, as excessive volume may worsen right ventricular failure. Vasopressors may be required if hypotension persists.
Anticoagulation is the cornerstone of treatment, preventing further clot formation and stabilizing existing thrombus. Unfractionated heparin requires close monitoring with target activated partial thromboplastin time 1.5–2.5 times control. Low-molecular-weight heparin (e.g., enoxaparin 1 mg/kg SC every 12 hours) is at least as effective and easier to administer. Long-term therapy includes warfarin (target INR 2–3) or direct oral anticoagulants such as rivaroxaban (15 mg twice daily for 3 weeks, then 20 mg daily). Rivaroxaban does not require routine monitoring but is not recommended in renal or hepatic insufficiency or pregnancy.
Thrombolysis (e.g., alteplase 100 mg IV over 2 hours) is indicated in hemodynamically unstable patients with confirmed PE and may be considered in selected stable patients with massive PE, severe hypoxemia, or right ventricular dysfunction. Inferior vena cava filters are reserved for patients with contraindications to anticoagulation or recurrent PE despite therapeutic anticoagulation. Surgical or catheter-directed embolectomy may be considered in select unstable patients.
All patients diagnosed with PE require hospital admission for monitoring and anticoagulation. In selected stable patients with high suspicion and no contraindications, empiric anticoagulation may be started while awaiting definitive imaging if diagnostic resources are temporarily unavailable.
The clinical presentation of PE is highly variable and often mimics other conditions such as myocardial infarction, pneumonia, asthma, pneumothorax, or anxiety. Maintaining a high index of suspicion is essential. Patients with malignancy are at increased risk of recurrent PE despite therapeutic anticoagulation. Early risk stratification and prompt treatment significantly reduce morbidity and mortality.
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