Bod: Respiratory: Pulmonary Thromboembolism

Front 1

What is (by far) the most important type of embolic phenomenon?

Back 1

Acute pulmonary thromboembolism.

Front 2

What are the five types of embolic phenomena?

Back 2

1. Pulmonary embolism
2. Fat embolism
3. Air embolism
4. Amniotic embolism
5. Tumor embolism

Front 3

What is the most frequent cause of thromboembolism?

Back 3

Disease states that slow venous return (especially in the lower extremities).

Front 4

What causes slowing of venous return in the lower extremities?

Back 4

CHF
Trauma
Surgery (especially from prostatectomy)
Fractures
Immobilization

Also:
Increased platelets
Alterations in clotting factors
Certain drugs

Front 5

What commonly-used drug is associated with DVT?

Back 5

Birth control pills. The estrogen in the pills increases the risk.

Front 6

What are some factors that can dramatically increase the likelihood of developing a DVT in a woman on birth control pills?

Back 6

Smoking
Increasing maternal age

Front 7

What hormone increases the risk of DVT?

Back 7

Estrogen.

Front 8

Where is the most frequent site of venous thrombosis?

Back 8

In the veins of the leg/calf, including the femoral and illiac veins.

Front 9

Where do thrombi often form in pregnant and post partum women?

Back 9

In the pelvic veins

Front 10

Thrombus formation with sepsis and intravascular catheters?

Back 10

Internal jugular vein and the SVC.

Front 11

Thrombus formation with atrial fibrillation?

Back 11

The right atrium.

Front 12

Thrombus formation in catheterized neonates?

Back 12

In the umbilical veins

Front 13

What are the repeating layers of fibrin and platelets found in thrombi?

Back 13

Lines of Zahn

Front 14

Lines of Zahn are found most commonly in what type of emboli?

Back 14

In arterial emboli

Front 15

What are the most striking findings of air embolism at autopsy?

Back 15

1. Frothy blood in the pulmonary ateries.

2. The right atrium and pulmonary artery are dilated.

3. The contracted left atrium is empty.

4. Pulmonary effusions/edema

Front 16

What should be on the differential diagnosis of an air embolus?

Back 16

Clostridial sepsis with gas formation. Gas will be foul smelling and will be present in all four chambers of the heart, other organs (subcapsular vessels of the liver, GI, spleen), and systemic/pulmonary vessels. Will also see a "dark, dirty" staining of the intimal surface of the vasculature.

Front 17

When do you see fat emboli?

Back 17

With fractures. The more extensive, the more emboli you see. Clinical presentation can vary.

Front 18

How do you visualize fat with staining?

Back 18

Oil Red O stain

Front 19

What is the mechanism of amniotic fluid embolism?

Back 19

Partial detachment of the placenta followed by continued uterine contractions forcing fluid into the placental vessels.

Front 20

What are the only two organs with a dual blood supply?

Back 20

The lung and the liver.

Front 21

Why are infarcts of pulmonary parenchyma rare?

Back 21

Because the lung is supplied by both the pulmonary and bronchial vasculature.

Front 22

Where do most lung infarcts occur?

Back 22

75% in the lower lobes, often at the costophrenic angles. Infarcts are usually pyramidal or wedge shaped.

Front 23

What is a complication of pulmonary infarct that happens in 2-3% of cases?

Back 23

Bacterial infection with resultant lung abscess.

Front 24

Of the 5-6 million cases of DVT a year in the US, how many lead to PE?

Back 24

About 10%. 10% of these die in the first hour.

Front 25

What is the etiology of venous thrombosis? (3)

Back 25

- Venous stasis
- Intimal injury
- Hypercoagulable blood

Front 26

What are some factors that make people at high risk for PE?

Back 26

- Injury to the lower extremity or pelvis.
- Surgery of the lower extremity.
- All surgical procedures with general anesthesia
- Burns
- Pregnancy (also post-partum)
- Previous history of DVT with residual obstruction
- RVF
- Prolonged immobility

- Age over 70
- Obesity
- Cancer
- Use of estrogen containing compounds

Front 27

What are the four fates of a thrombus?

Back 27

1. Resorption
2. Incorporation into the wall of the vein
3. Rupture and travel proximally
4. Growth leading to occlusion

Front 28

Besides size, what is another factor determining the physiological consequences of a thrombus?

Back 28

Platelets in the thrombus release vasoactive substances that can lead to vasoconstriction.

Front 29

Acute pulmonary embolism: presentation, physical exam

Back 29

- Very high PA pressures
- Rapidly failed RV
- Subsequent fall of CO and systemic blood pressure.

Physical exam:
- Dyspnea, pleuritic chest pain, apprehension, cough, hemoptysis, diaphoresis, syncope
- Tachypnea, rales, pleural friction rub, increased S2 sound, tachycardia, fever, signs of venous thrombosis in legs.

Front 30

Why is it important to diagnose and treat even a small pulmonary embolism?

Back 30

Because the likelihood of another PE happening is very high.

Front 31

What A-a defect does PE cause?

Back 31

It causes an increase in anatomical dead space.

(even so, PaO2 is decreased. Minute ventilation increases out of proportion to the increase in alveolar dead space.)

Front 32

The hypoxemia and the increased A-a gradient seen with pulmonary embolism is due to what three factors?

Back 32

1. RHF --> low CO --> low venous O2 --> low PaO2

2. PE --> high pulmonary pressures --> areas of poor ventilation are perfused --> V/Q mismatch --> hypoxemia

3. High pulmonary pressures may cause blood to flow through a patent foramen ovale --> paradoxical emboli --> embolus in arterial circulation

Front 33

What clinical presentation suggests chronic PE?

Back 33

- Dyspnea
- PFTs show normal lung volumes and flow rates.
- Reduced diffusing capacity.

Front 34

What is the differential diagnosis of chest pain?

Back 34

- PE
- MI
- Pleurodynia (Coxsackie B)
- Costochondritis
- Pneumothorax

Front 35

What is the differential diagnosis of dyspnea?

Back 35

- Asthma
- COPD exacerbation
- Pneumonia

Front 36

What is the differential diagnosis of hemoptysis?

Back 36

- COPD exacerbation
- Pneumonia
- Malignancy

Front 37

What does a positve D-dimer tell you?

What does a negative D-dimer tell you?

Back 37

Nothing. Need to keep looking so that you can rule out a PE.

A negative D-dimer tells you that there is likely no PE present

Front 38

Currently, what is the most favored method of testing for PE?

Back 38

The rapid ELISA test.

A D-dimer level < 500 ng/mL as measured by ELISA is sufficient to exclude PE (unless pretest probability is high)

Front 39

What is the accepted diagnostic test to assess for the the presence of thrombus in the lung?

Back 39

Spiral chest CT scan with contrast angiography.

Front 40

What does a "low probability" or "indeterminate" reading on a V/Q mismatch scan indicate?

Back 40

That there is at least a 30 to 50% chance that the patient has had a PE.

Front 41

What is the "gold standard" for detecting PE?

Back 41

The pulmonary angiogram

Front 42

Why is it so important to determine if a PE is present or not?

Back 42

Because the therapy for a PE, anti-coagulation, could be disasterous if the patient has an aortic dissection instead of a PE.

Front 43

PE: treatment

Back 43

- Heparin for 7-10 days followed by
- Coumadin for 3-6 months
- Elimination of underlying risk factors.

Front 44

If you have PE, what is the chance that you might get another?

Back 44

Approximately 35%

Front 45

What is the goal of anticoagulation therapy for PE?

Back 45

To prevent another PE. Treatment with heparin may also speed resolution of thrombus in the lung.

Front 46

What can be done for a patient with a history of PE and a history of adverse reactions to anticoagulation?

Back 46

An SVC or IVC filter can be put in.

Front 47

DVT/PE: prevention

Back 47

- Heparin injections
- Pneumatic boots