| Current Concepts: |
|
Blocking of the pulmonary
artery by foreign matter such as a blood
clot, fat, air, tumor tissue.
The third most common cause of death in
hospitalized patients.
Most patients with DVT develop PE (Majority
of cases are unrecognized clinically).
Untreated, approximately 1/3 of patients who
survive an initial PE die of a future
embolic episode.
|
| Frequency: |
In the US:
►60% of
patients who died in hospitals had PE.
The diagnosis was missed in up to 70%.
Prospective studies demonstrated DVT in:
►10-13% of all
medical patients placed on bed rest for 1
week,
►29-33% of all
patients in medical ICUs,
►20-26% of
patients with pulmonary diseases who stays
at bed for ≥3 days,
►27-33% of
those admitted to a critical care unit after
MI,
►48% of
patients who are asymptomatic after CABG. |
| Pathphysiology of PE: |
►VIRCHOW’S
TRIAD
Local trauma to vessel wall
Hypercoagulability
Stasis
►Hypercoagulable
state
Inherited (Primary)
Secondary (Acquired)
►Primary
Hypercoagulable states
►Acquired
Hypercoagulable states
|
| Non-imaging Diagnostic Methods: |
►PLASMA
D-DIMER ELISA
•Natural Break down of fibrin to D-Dimers
•Sensitive but not specific as it
•Increases in MI, repsis, cancer, any other
systemic
►ABG
•No difference between average PaO2 in
patients with and without PE
•Not part of diagnostic strategy
►ECG
•Exclude AMI
•Raise suspicion of PE
•Confirm the diagnosis
|
| Imaging Diagnostic Methods: |
►CXR
•Abnormal CXR in ¼ of patients.
•Focal oligemia (Westermark’s sign)
indicates massive central embolic occlusion.
•Peripheral wedge shaped density above the
diaphragm (Hampton’s hump) indicates
pulmonary infarction.
•Small pleural effusion.
|
| Spiral
or the new multi-detector CT: |
►Replacing
V/Q scan
►Replacing
pulmonary Angio in Dx
►More
specific, more accessible
►Provides
alternative diagnosis in 30% of cases
►May
miss sub segmental emboli
►Give
information about the size and function of
RV
►Requires
a high dose of injected contrast (can use
non iodinated contrast ) - check creatinine
►Diagnostic
even in the presence of an abnormal chest
radiograph
|
| Ventilation-Perfusion scan: |
►Perfusion
scan:
•Technetium 99m-labeled macro aggregated
albumin (MAA).
•injected intravenously.
►Ventilation
scan:
•Technetium 99m DTPA aerosol.
•Inhaled.
►Second
choice imaging test.
►70% of
patients have an indeterminate result and
need another test to make the diagnosis.
►Good in the
presence of a normal chest radiograph.
►Not helpful in
the presence of an abnormal chest
radiograph, in patients with COPD or cardiac
disease.
►Does not
provide an alternative diagnosis.
|
| Pulmonary angiography: |
►Was
the Gold standard, replaced by the new
multidetector CT scanning
►Invasive -
catheter inserted into femoral vein, up the
IVC through into right-sided cardiac
chambers and into pulmonary arteries.
►Contrast
injected directly into pulmonary arteries.
►Required when
interventions are planned as:-
•Suction catheter embolectmy.
•Mechanical clot fragmentation.
•Catheter directed thrombolysis.
|
| With MRA: |
Keep your tablets in the pack in which they were
supplied.
Keep your tablets below 30°C.
Keep your tablets in a safe place where children cannot see or reach them.
|
Author |
Year |
# of pt |
Techniques |
Sensitivity |
Specificity |
| Meanly |
1997 |
30 |
3D G |
87% |
97% |
| Gupta |
1999 |
36
|
3D Gd |
85% |
96%
|
|
|
Next |
