Pulmonary Embolism Flashcards
37 yr old female
Sudden onset right sided chest pain, pleuritic
Dyspnea associated with pain
Previously well
No symptoms of DVT or pneumonia
What is the differential diagnosis?

Doesn’t tell us the diagnosis, tells us the location
Air-space disease
Rounded area
RLL peripheral pulmonary infiltrate
DDx:
- Acute PE
- Pneumonia
What is pulmonary embolism?
Why is it important to know?
Blood clot in the lungs
Important because:
- Common
- Life threatening
- Challenging to diagnose
- Treatable
Why do PEs have so many different clinical presentations?
Because PEs most often come from DVTs, and can end up in many different areas of the lungs, leading to different clinical presentations.

Where do PEs originate from?
90% from DVT
10% from other large veins
NOT from superficial veins
What is VTED?
Venous thrombo-embolic disease
VTED = DVT + PE
Pathophysiological response to PE?
- Usually bilateral perfusion defects
- Infarct (large clots, other impairment, not common)
- Abnormal gas exchange
- Cardiovascular compromise (mechanical occlusion)
What does this path specimen show?

This image shows pulmonary infarct, from some compromise of the pulmonary blood flow.
Can occur with large PE, or with atherosclerosis of the pulmonary arteries
How do we diagnose PE?
- History (HPI, PMHx, risk factors)
- Physical exam
- CXR, EKG
- D-dimer
- V/Q scans
- Doppler US of legs
- Chest CT scans via ‘PE protocol’
Signs and symptoms of PE?
Dyspnea, pleuritic chest pain, hemoptysis (small volume)
Tachypnea, tachycardia, R-sided S4, loud P2, pleural rub, fever
Risk factors that increase PE?
- Immobilization
- Surgery (within the last 3 months)
- Malignancy (esp. pancreatic, prostate) Stroke
- Previous DVT/PE
- Heavy Smoking
- Obesity
- Hypertension
- Coagulation abnormalities ie..Factor V Leiden mutation
What initial tests do we order if we suspect PE?
Arterial blood gas
EKG - non-specific
Clinical pearl: if EKG signs of RV hypertrophy, think of chronic pulmonary vascular process, not just acute PE going on
CXR - non-specific
Radiographic features of PE?
Hampton’s Hump - wedge-shaped opacity in the lung, peripheral
Pleural effusion
Westermark sign - oligemia (dont see vessels) of one lung, from large burden of emboli
ADD PICTURES
What is the D-dimer test?
Non-specific test for PE; most common cause of false positive is pneumonia
High sensitivity (98%)
Poor overall specificity (30-50%)
How do we image for DVT?
Doppler US of the Leg
Look for non-compressible deep venous segments
If negative, useful in increasing negative predictive value of a chest imaging modality for acute PE
On it’s own, not useful. Clot may have embolized already.
What do we use the Wells Score for?
Wells score is used to determine the clinical (pre-test) probability that a patient has a PE
Low risk: 0-1
Int risk: 2-6
High risk: > 6 (high pre-test suspicion)
Modified Wells Score
PE unlikely: 0-4
PE likely: >4
What is this scan?

Ventilation perfusion scan
Patient breathes in radio-labelled particles
Rotated images at 360 degrees
Also inject venously with labelled particles and look at lung
Looking for an area where there is ventilation, but a defect in perfusion
Posteriorly there is a large defect
What did the PIOPED study find about Wells Score and V/Q test?
If you have high prob of PE from V/Q scan, and high clinical probability based on Wells, 96% actually have PE.
V/Q is only useful in some scenarios:
When Well’s is high and V/Q suspicion is high
When V/Q suspicion is NORMAL, predicts NO PE despite Well’s score being high
If the patient has a LOW Well’s pre-test score, we DON’T order teh V/Q scan because it leads to false-positives

When is the V/Q scan useful?
- High probability Result: IF High pretest probability → Post test probability of PE is very high (96%) and can use to diagnose PE
- Intermediate probability Result: Non-diagnostic
- Low probability Result: Non-diagnostic in most cases
- Normal/near normal Result —> High sensitivity → can use to exclude PE
What is this image?

Coronal image of a CT Pulmonary Angiogram
Left is normal
Right has positive filling defect in the RLL, consistent with PE
When is the CTPA useful as a diagnostic tool?
High pretest probability with positive CTA : Post test probability of PE is very high (96%); can be used to diagnose PE
Low pretest probability with positive CTA : Only 58% have PE; thus false positives exist when test ordered in this situation
High pretest probability with negative CTA : 60% still have underlying PE. Further testing required.
Low pretest probability with negative CTA : Useful to rule out PE
The same is true for when it is useful to image the legs to rule in or out a PE.
What algorithm do we go through to determine how to investigate a potential PE?
Determine if PE is likely or unlikely using Modified Wells Score, and go from there using this flow chart
D-dimer done first in some cases because it is cheap, easy, and has a good negative predictive value.
(if patient has likely PE, and then a negative CTPA, consider doing extra testing to confirm - leg doppler, other imaging)

What occurs to the pulonary arterial pressure (PAP) when a patient has a massive PE?
What can result from these changes in PAP?
If a patient has more than 50% obstruction, there is often an increase in PAP. With 75% obstruction, the meanPAP can increase close to 40 mmHg, which results in RV failure.
This hemodynamic compromise leads to hypoxemia –> vasoconstriction –> further increase in meanPAP –> RV “death spiral”
(Underlying heart disease is associated with worse outcomes with acute PE for this reason)
What are the signs, symptoms, and findings of a massive PE, with obstruction of the artery?
Symptoms: severe dyspnea, syncope
Signs: tachycardia, tachypnea, hypotension, increased JVP, R-sided S3, increased P2, RV lift
CXR: nonspecific, westermark sign
EKG: S1Q3T3, new R bundle branch block, inverted T waves (precordial)
Echo: dilated RV, septal deviation
What is the main treatment for PE?
Anticoagulation: initial and chronic
IVC filter: for those who cannot be anti-coagulated; increased risk for distal DVT
Massive PE: standard anti-coagulation + thrombolysis
What is used for inital anticoagulation?
Chronic anticoagulation?
Initial: LMWH (sometimes Fondaparinux)
Chronic: warfarin, oral FXa inhibitor (rivaroxaban, apixaban
What is CTEPH?
Chronic thromboembolic pulmonary hypertension
Incomplete PE resolution in approximately 4% of all PEs
Treated surgically

How do we monitor patients with PE?
- Monitor anticoagulation
- Watch for complications (infarct, unstable)
- CTEPH
- Complications of therapy itself (bleeding, HIT)
- Risk of VTE recurrence and bleeding