#21 - Pulmonary Embolism Flashcards
T/F: Physical exam and history can reliably diagnose PE.
false. diagnosis off Physical exam/history is no better than chance. Get a pulmonary angiogram or CT!
gold standard diagnostic test for PE.
pulmonary angiogram
Most commonly used diagnostic test for PE.
CT scan. (pulmonary angiogram= gold standard, but hard to get.)
Uses/limitations for D-dimer test ( how helpful?)
- very sensitive
- not very specific
- high false positive rate due to post-surgery increase
- can rule out, but not confirm, PE.
pros and cons of CT testing for pulmonary embolism
technology and image are excellent, but they are expensive, not portable, need expertise to interpret, and may identify a clinically insignificant PE.
T/F: if there is no pulmonary embolism on a CT scan, it is safe to rule out PE.
True.
When is it safe to withhold anti-coagulants when you are unsure if there is a pulmonary embolism?
- low/mild Wells score
- normal or low V/Q scan (it is high in PE)
- low D-dimer (can rule out PE)
If you are administering unfractionated heparin, what should you monitor?
Monitor PTT, aim for 1.5-2x normal value.
advantage of Low molecular weight heparin
- don’t need lab monitoring as frequently (reliable dosing)
- decreased heparin-induced thrombocytopenia
Warfarin interferes with the production / maturation of which clotting factors?
factors 2,7,9,10,
protein C and S
T/F -
Warfarin can cause a hypercoagulable state
True - due to blocking protein C/S before other clotting factors.
This is why you should overlap with heparin for at least 5 days.
When is thrombolytic therapy indicated?
-for a massive PE when systolic BP
Where do most pulmonary emboli come from?
The proximal ileo-femoral veins. Thrombi in these veins can grow/extend asymptomatically and recurrently embolize when not treated.
Recommendations for preventing pulmonary embolism in low bleed risk patients
heparin (either form)
Recommendations for preventing pulmonary embolism in high bleed risk patients
pneumatic stocking (prevent pooling / thrombosis)
Major risk factors for PE
- immobilization
- surgery w/in three months
- stroke
- history of VTE
- malignancy (cancer)
T/F if chest wall pain is reproducible with pressure, this makes PE a more likely diagnosis
FALSE. worthless.
Also of note: pulse ox may be normal in 20% of cases of PE
what is hampton
s hump?
pleural-based, wedge shaped density.(infiltrate) on CXR. This is pathognomonic for PE, but rarely seen
T/F Most EKG’s are abnormal in PE patients
TRUE.
But they are not abnormal in a characteristic pattern - so it is not very helpful in diagnosis (insensitive and nonspecific).
Value of V/Q scan in diagnosing PE
if you have high pretest clinical probability, and it is positive, you can rule in PE. If you have low pretest probability and it is low, you can rule out. However, it isn’t of much use for patients in between (which is a lot of patients). Today it has been supplanted by CT angiography.
D - dimer is described a “unidirectional test” what does that mean?
-it is much more helpful when it is negative ,b/c you can rule PE out, but not helpful if +.
(it is sensitive, but not very specific)
positive value for D-dimer
traditionally >500
New - pt age x 10 (eg 69 year old, positive value would be >690)
-this new method is validated and better, fewer false +
role of lower extremity doppler ultrasound in diagnosis of PE
it is specific - if you see a deep vein thrombus on ultrasound, stop testing and treat (same treatment for DVT and PE).
However, low sensitivity (30-40% of patients with PE have negative ultrasound).
-if it’s negative and you can’t do CT angio….
-do serial testing (higher probability)
or do pulmonary angiography
Indications for getting a Chest CT angiogram
Wells >4
OR..
positive D-dimer
What should you do if Wells score is
get a d-dimer. if positive, get CT. If it is negative, rule out PE.
Treatment of new, confirmed pulmonary embolism
anticoagulation for 3 -6 months. After discontinuing, do a d-dimer after a month and resume treatment if +.
treatment of recurrent pulmonary embolism
anticoagulate for a year, maybe indefinitely, depending on risk/benefit.
Ideal INR in a patient on warfarin
in between 2.0 and 3.0
Certain medications are now replacing warfarin. What is their mechanism? - 2 mechanism
they inhibit factor 10a directly, or inhibit thrombin directly.
What is the downside of direct factor 10 inhibitors and direct thrombin inhibitors?
- cannot use in renal failure patients
- expensive
- no reversal agents.
utility of IVC filters for preventing PE.
not much value - poor data
