Pulmonary Embolism

The combination of being potentially lethal coupled with a very variable or no definite clinical presentation makes this disease the clinician’s worse fear.

Pathophysiology:  A variety of mechanisms leading to increased coagulability.  Often seen in association with bed rest (post-surgical patient), immobility, venous stasis and leg edema, and in patients with hypercoagulable states (birth control medication, cancer patient, protein C/S deficiency etc…)

Clinical Clues: The patient may be symptomatic (shortness of breath, dyspnea, pleuritic chest pain) or almost asymptomatic presenting with unexplained lab or CXR findings.

The clinical index of suspicion plays a pivotal role in the radiologic workup of the patient.

CXR Findings:

1.      Normal, in nearly 50% patients with proven PE

2.      Prominent central pulmonary artery: Fleishner’s sign

3.      Distal pulmonary artery cut-off and oligemia: Westermark’s sign

4.      Hampton’s hump: peripheral wedge shaped area of consolidation

5.      Pleural effusion

6.      Pulmonary edema and failure

Imaging for PE:

1.      CXR: not definitive

2.      Ventilation-perfusion scanning.  Usually not very helpful.  May be useful in patients with low clinical suspicion, normal CXR alongside normal V/Q scan.

3.      **CT thorax with PE protocol (new gold standard)

4.      Pulmonary angiography. (old gold standard)

5.      Doppler ultrasound of leg veins

What if we miss a small peripheral emboli?

Controversial: most clinicians state that it is the big emboli that kill patients.  The clinical sequelae of missing small or subsegmental emboli may not be serious. This issue has not been resolved yet.