Definition
A.A blockage of a pulmonary artery or one of the smaller branches. Most commonly, pulmonary embolism (PE) is the result of an embolic thrombus formation elsewhere in the body (e.g., lower extremity).
Incidence
A.PE is more common in patients with deep vein thrombosis (DVT).
B.It affects more than 600,000 people annually.
C.An estimated 60,000 to 100,000 people die annually.
D.Approximately one-third of patients will have a recurrence within 10 years.
Pathogenesis
A.A thrombus forms secondary to a hypercoagulable state, injury to the vascular endothelium, and venostasis, which concentrates blood clotting factors at the site of vessel injury. Clot formation occurs as a result of blood pooling.
B.The clot can dislodge from the extremity, travel through the venous system, move through the right side of the heart, and obstruct a pulmonary artery or the smaller branches. Large enough obstructions can prevent blood flow to the affected area, creating a ventilation/perfusion mismatch leading to respiratory failure and/or increase the pulmonary artery pressure, resulting in right-sided heart failure.
Predisposing Factors
A.Factor V mutation.
B.Protein C or S deficiency.
C.Malignancy.
D.Immobility.
E.Trauma.
F.Surgery.
G.Smoking.
H.Obesity.
I.Prior PE.
J.Chronic diseases such as heart failure and chronic obstructive pulmonary disease (COPD).
K.Prolonged travel.
Subjective Data
A.Common complaints/symptoms.
1.These can vary depending on the degree of clot burden.
2.Patients may be asymptomatic, especially in the setting of a small segmental branch PE. The condition is usually found incidentally in these cases.
3.Symptoms may include:
a.Pleuritic chest pain.
b.Dyspnea/Tachypnea.
c.Hypoxia.
d.Cough with possible blood-tinged sputum production.
e.Tachycardia.
f.Dizziness or syncope.
g.Hypotension/shock with a massive PE.
h.Recent symptoms associated with a DVT (e.g., extremity pain, warmth, erythema, edema).
B.Family and social history.
C.The provider should assess symptom onset and any associated risk factors for PE development such as history or current malignancy, decreased mobility, travel, recent surgeries, and so forth.
D.It is important for the provider to assess for family history of clot formation or known factor deficiencies.
Physical Examination
A.Findings depend on the degree of clot burden.
B.Perform a general examination, which may reveal diaphoresis, fever, and tachycardia. On presentation, most patients are hemodynamically stable.
C.Assess neurological status. Patients may present with syncope, altered mentation, or agitation.
D.Assess the respiratory rate. In more significant PEs, the rate will be increased. Auscultation of breath sounds may reveal rales or crackles.
E.Perform a cardiac examination. Patients may have a murmur, accentuated second heart sound, or S3/S4 gallop.
F.Extremities may reveal signs of a deep vein thrombosis such as pain, edema, or erythema.
Diagnostic Tests
A.D-dimer (age adjusted).
1.High sensitivity: With negative results and a low probability of a PE.
2.Most reliable in young patients with no comorbid conditions and short symptom onset.
3.Can have nonspecific elevations in the elderly and those with other acute illnesses requiring hospitalization.
B.Chest CT Angiography (CTA).
1.Allows for direct visualization of the emboli.
2.Considered the standard of care for diagnosing patients with high probability of a PE or low/intermediate probability but positive D-dimer.
3.Right ventricular (RV) dilation: Associated with short-term adverse outcomes.
C.Ventilation/Perfusion (V/Q) Lung Scan.
1.An alternative to the chest CTA, especially in the setting of contraindications such as renal failure.
2.Evaluates for perfusion defects, which are nonspecific and only present in one-third of patients with PE.
3.Increased likelihood of nonconclusive results in patients older than 75 years.
D.Echocardiography.
1.Often indirectly helps diagnose PE in conjunction with the patient’s clinical presentation.
2.Can also be utilized as a prognostic factor in PE.
3.Possible findings consistent with a PE: Acute RV enlargement and in some cases dysfunction, evidence of pulmonary hypertension with elevated RV systolic pressures, and possible flattening of the septum.
4.May be able to visualize an intracardiac thrombi.
5.RV dilation: Associated with an increased risk for adverse outcomes.
E.Ultrasonography.
1.Can assist in the diagnosis of PE.
F.Additional diagnostics for acute risk stratification.
1.Pulmonary embolism severity index (PESI).
a.Used to predict the 30-day outcomes/mortality in patients with acute PE.
b.Score greater than 106 on the original PESI: High risk for morbidity and mortality.
c.Score greater than 1 on the simplified PESI: High risk for morbidity and mortality.
2.Troponin.
a.Elevated troponin levels in patients presenting or receiving treatment for PE: Associated with adverse outcomes.
3.N-Terminal pro brain natriuretic peptide (NT-proBNP).
4.Elevated levels: Associated with adverse outcomes (in literature).
Differential Diagnosis
A.Pericarditis.
B.Pleuritis.
C.Musculoskeletal pain.
Evaluation and Management Plan
A.General plan.
1.Diagnosis of a PE requires the provider to account for the patient’s clinical presentation as well as evaluating diagnostic tests.
2.Treatment recommendations are highly dependent on the patient’s clinical status including respiratory and hemodynamic stability at the time of presentation.
3.In the clinical setting and literature, PEs have been described as low risk, submassive, and massive.
a.Low risk PEs: Patients with hemodynamic stability, no elevation in biomarkers, and no evidence of RV dysfunction on imaging.
b.Submassive PEs: Patients with hemodynamic stability but evidence of RV dysfunction on imaging and/or biomarker elevation.
c.Massive PEs: Patient with hemodynamic instability, elevation in biomarkers, and evidence of RV dysfunction.
4.Ideally, patients should have pretest clinical assessment, diagnostics with consideration of risk stratification, and initiation of treatment.
5.Low to intermediate probability of PE.
a.Pretest clinical assessment.
i.Wells Clinical Prediction Rule for PE. Patients are evaluated using seven variables in which they can receive 1 to 3 points. A score of 2 to 6 points indicates a moderate risk and a score greater than 6 indicates high risk.
ii.Revised Geneva Score. Patients are evaluated using eight variables in which they can receive 1 to 5 points. A score of 4 to 10 points indicates an intermediate risk and a score greater than 11 indicates high risk.
iii.Appropriate for patients who are hemodynamically stable. Patients with a high probability of PE should proceed immediately to diagnostic testing.
b.Age-adjusted D-dimer.
i.If negative: No further imaging needed.
ii.If positive: Further imaging needed.
iii.It is important that the provider use an age-adjusted scale due to decreased specificity