Pulmonary Embolism for NP
Pulmonary Embolism for the Nurse Practitioner Licensing Exam
Etiology and Risk Factors
- Pulmonary Embolism (PE):
- PE occurs when a thrombus, usually from the deep veins of the lower extremities or pelvis (DVT), dislodges and obstructs a pulmonary artery.
- Virchow’s Triad:
- PE is associated with:
- Endothelial injury: Surgery, trauma, or vascular inflammation.
- Venous stasis: Prolonged immobility, such as during hospitalization or long flights.
- Hypercoagulability: Conditions such as pregnancy, malignancy, oral contraceptive use, and genetic factors (e.g., factor V Leiden).
- Additional Risk Factors:
- Recent surgery, immobilization, obesity, smoking, malignancy, and pregnancy.
Pathophysiology
- Clot Formation and Migration:
- A thrombus forms in the deep veins, travels through the venous circulation, and lodges in the pulmonary arteries, causing a block in blood flow.
- Hemodynamic Impact:
- The obstruction increases pulmonary vascular resistance, leading to right ventricular strain and potentially right heart failure in large PEs.
- Ventilation-Perfusion Mismatch:
- Blood flow is diverted from obstructed areas, resulting in hypoxemia due to impaired gas exchange.
Clinical Features
- Symptoms:
- Dyspnea: Sudden onset, common in most patients.
- Pleuritic chest pain: Sharp pain, exacerbated by breathing or coughing.
- Tachypnea and tachycardia are often present.
- Cough: Sometimes accompanied by hemoptysis.
- Leg swelling or pain: May suggest DVT as the source of the embolus.
- Massive PE:
- Symptoms include syncope, hypotension, and shock due to severe right heart strain.
Diagnosis
- D-dimer:
- Elevated in most cases of PE but nonspecific. A negative result can rule out PE in low-risk patients.
- CT Pulmonary Angiography (CTPA):
- The gold standard for diagnosing PE, directly visualizing the thrombus.
- V/Q Scan:
- Alternative for patients with contraindications to contrast. Shows ventilation-perfusion mismatch.
Management
- Anticoagulation:
- Low-molecular-weight heparin (LMWH) or direct oral anticoagulants (DOACs) like rivaroxaban are preferred.
- Thrombolysis with alteplase (tPA) in massive PE with hemodynamic instability.
- Long-term anticoagulation:
- Continued for 3-6 months or longer based on the cause (provoked vs. unprovoked).
Key Points
- Pulmonary embolism results from thrombi, typically from DVT, obstructing the pulmonary arteries.
- Risk factors include immobility, recent surgery, malignancy, and pregnancy.
- Common symptoms include sudden dyspnea, pleuritic chest pain, and tachycardia.
- Diagnosis is confirmed with CT pulmonary angiography or V/Q scan. D-dimer is useful for ruling out PE in low-risk cases.
- Treatment involves anticoagulation and, in severe cases, thrombolysis. Long-term management depends on the underlying risk factors.