- • Clinicians should be aware of individual risk
factors for development of pulmonary embolism.
- • Pulmonary embolism should be considered in cases
of unexplained hypoxemia.
- • Limitations exist for all current diagnostic studies.
- • All clinicians should have a diagnostic algorithm
in cases of suspected pulmonary embolism.
Venous thromboembolism (VTE), a common medical problem, is the
third most common vascular disease and carries a high morbidity
and mortality. It is characterized by intravenous thrombus formation
either as a deep venous thrombosis (DVT) in leg veins or as a pulmonary
embolism (PE), a thrombus migrating to the lung circulation from
proximal leg veins or the pelvis. Risk of venous thromboembolism
rises with increasing age, up from 1:10,000 in childhood to 1:100
in the elderly. It is estimated that DVT occurs in 1 of 1000 adults
and PE in 10–25% of these patients. Both conditions
are difficult to diagnose due to their nonspecific symptoms and
signs. As a result, many cases are recognized only postmortem or
after a thrombus has migrated to the lung circulation. Therefore,
it is extremely important to identify patients at risk to facilitate
prompt diagnosis and management (Table 19–1).
An algorithm can be instrumental in doing this. Because the thrombi
originate in the legs, PE is potentially avoidable if preventive
therapy, such as anticoagulation or compression stockings, is used
in high-risk situations.
Risk Factors for Venous Thromboembolism. |Favorite Table|Download (.pdf)
Risk Factors for Venous Thromboembolism.
|Prolonged air travel|
|Congestive heart failure|
|Fractures of the lower extremities|
|Femoral catheters/other central venous catheters|
|Hypercoagulable conditions (malignancy, oral contraceptives, Protein C and S deficiency, Factor V Leiden
mutation, anti-thrombin III deficiency)|
|Chronic respiratory failure|
Presenting signs and symptoms for pulmonary embolism are nonspecific,
which makes clinical diagnosis difficult. The most common presenting
symptoms noted in the patients from the Prospective Investigation
of Pulmonary Embolism Diagnosis (PIOPED) study who had angiographically
confirmed PE were dyspnea, pleuritic chest pain, and tachypnea.
The findings on physical examination included increased respiratory
rate, rales, tachycardia, a loud second heart sound, deep venous
thrombosis, temperature above 38.5°C, wheeze, Homan’s sign
(pain on palpation of the calf), pleural friction rub, an S3 gallop,
and cyanosis. Syncope or hypotension may uncommonly be the presenting
symptoms of pulmonary embolism and suggests severe hemodynamic compromise.
The presence of the above clinical findings can heighten concern
for PE but does not constitute a diagnosis.
Although clinical symptoms and signs are nonspecific, clinical
models using findings from history and physical examination help
focus clinical suspicion for PE. Recent clinical models use weighted
clinical scores to assign low, moderate, or high clinical probability
of a PE. Some use clinic assessment plus a noninvasive diagnostic
test, such as the d-dimer assay that ...