Respirology - Pulmonary Embolism

Front 1

What is a pulmonary embolism?

Back 1

The term pulmonary embolism, or, more precisely, pulmonary thromboembolism refers to movement of a blood clot from a systemic vein through the right side of the heart to the pulmonary circulation, where it lodges in one or more branches o the pulmonary artery.

Front 2

What is Virchow’s classic triad of factors that predispose to clot formation?

Back 2

Stasis, hypercoagulability, and trauma

Front 3

Name five hypercoagulable states.

Back 3

Obesity, malignancy, pregnancy, oral contraceptives, anti-phospholipid antibody syndrome, factor V Leiden

Front 4

Name three types of trauma associated with pulmonary embolism.

Back 4

Surgical, non-surgical, and central-line associated

Front 5

Describe the pathophysiology of pulmonary embolism.

Back 5

1) Dead-space-type V/Q mismatch distal to clot (ventilation but no perfusion)

2) Bronchoconstriction secondary to mediator release → shunt-type V/Q mismatch (perfusion but not ventilation)

3) Increased pulmonary vascular resistance → right sided heart failure

Front 6

What is the primary consequence of dead-space-type V/Q mismatch?

Back 6

Hypercarbia

Front 7

What is the primary consequence of shunt-type V/Q mismatch?

Back 7

Hypoxemia

Front 8

What is the most common CO2 abnormality seen in patients with pulmonary embolism?

Back 8

Hypocarbia secondary to hyperventilation

Front 9

What are the clinical symptoms of pulmonary embolism?

Back 9

Sudden onset dyspnea, chest pain, cough/hemoptysis, syncope

Front 10

Other than these symptoms, what else would you want to ask the patient about in history?

Back 10

Risk factors for PE:

Stasis – bed-ridden, long periods of travel

Trauma – recent surgeries, trauma, line insertion

Hypercoagulability– malignancies, pregnancy, obesity, antiphospholipid antibody syndrome, factor V leiden, clotting in family members, oral contraceptives

Front 11

What are the clinical signs of pulmonary embolism you might notice on physical examination?

Back 11

Low-grade fever

Hypotension

Signs of right sided heart failure: distended jugular veins, P2, holosystolic murmur of tricuspid regurgitation, right ventricular heave

Signs of DVT in lower extremities

Front 12

What will you hear on auscultation of the patient’s lungs?

Back 12

Lungs will be relatively clear helping to distinguish PE from other causes of dyspnea

Front 13

What is a massive pulmonary embolism?

Back 13

PE that causes a systolic blood pressure of <90 mm Hg or a sustained drop in blood pressure >40 mm Hg

Front 14

What scoring system is used to predict the pre-test probability that the patient has a PE?

Back 14

Modified Wells Score

Front 15

What are the 7 parameters that make up the modified Wells score?

Back 15

1) Clinical signs or symptoms of DVT

2) Alternative diagnosis less likely

3) Tachycardia (HR >100)

4) Immbolization or surgery in past 30 days

5) Previous DVT or PE

6) Known malignancy

7) Hemoptysis

Front 16

When calculating a modified Wells score, how many points do you assign for each of the following:

Clinical signs of DVT

Back 16

3 points

Front 17

Alternative diagnosis less likely

Back 17

3 points

Front 18

Tachycardia (HR > 100)

Back 18

1.5 points

Front 19

Immobilization/surgery in past 30 days

Back 19

1.5 points

Front 20

Previous DVT/PE

Back 20

1.5 points

Front 21

Known malignancy

Back 21

1 point

Front 22

Hemoptysis

Back 22

1 point

Front 23

What modified Wells score predicts a low likelihood of PE?

Back 23

<2

Front 24

What modified Wells score predicts a high likelihood of PE?

Back 24

>6

Front 25

What two diagnostic imaging tests should be ordered in a patient with a high pre-test probability of PE?

Back 25

PE protocol CT scan (CT angiogram)

Lower extremity compression ultrasonography (“Dopplers”)

Front 26

What other diagnostic studies would you order for a patient with possible PE?

Back 26

Laboratory investigations:

ABG, D-dimer, cardiac enzymes (for ACS), BNP (for CHF), BUN/creatinine, anti-phospholipid antibody

Imaging studies:

ECG, chest X-ray, perfusion scan for patient who can't have CT with contrast

Front 27

What is D-dimer?

Back 27

D-dimer is a fibrin-degradation product, a fragment of protein that is present in the blood after a blood clot is degraded by fibrinolysis.

Front 28

When is it useful to get a D-dimer level?

Back 28

When the clinical suspicion for PE is low (Wells <2)

In this scenario, a negative test essentially rules out PE, since the test is sensitive but not specific.

Front 29

Is a D-dimer useful when you have a high clinical suspicion for PE? Why or why not?

Back 29

Not useful. The D-dimer is used to rule OUT PE (sensitive), but if your pre-test probability is high it can’t do that.

Front 30

Pre-test probability for PE is low. The D-dimer returns positive. What does this test result mean?

Back 30

Little, as D-dimer, though sensitive, is not specific.

Front 31

What determines the initial management strategy in pulmonary embolism?

Back 31

Patient’s hemodynamic stability (i.e. submassive vs. massive pulmonary embolism)

Front 32

What is the initial treatment for the stable patient with submassive pulmonary embolism?

Back 32

Subcutaneous low-molecular weight heparin (enoxaparin)

Front 33

What is the initial treatment for the unstable patient with massive pulmonary embolism?

Back 33

Fluid resuscitation
Thrombolytics (alteplase)

Front 34

What is the long-term treatment for the patient who has had PE?

Back 34

Anticoagulant prophylaxis
TED hose

Front 35

What medication is used for long-term anticoagulation prophylaxis in patients who have had a PE?

Back 35

Warfarin

Front 36

How long do patients who have had a PE have to remain on warfarin?

Back 36

Depends on their risk for recurrence, but should be at least 6 months.

Patients with a known malignancy should remain on warfarin for life.