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Question 1

Definitions for Thrombo-Veno-Embolism

Answer 1

DVT: Deep vein thrombosis

A blood clot develops in the deep veins of the legs (femur),

 but may arise in the arms, or on pacemaker lines or other intra
vascular devices.
 The primary condition located in the systemic deep veins
usually the legs or pelvic veins.

Pulmonary Embolism (PE)

A DVT dislodges and is swept into the lungs where it
causes occlusion of a or more pulmonary arteries
 A complication of DVT and
 May be fatal if large enough or occur repeatedly

Thrombus in situ of pulmonary arteries
 is thought very rare, but may be important among
patients with severe pulmonary hypertension in
whom customary to recommend AC treatment

Pulmonary infarct (i.e. ischemic necrosis of the
 lung),
  Is rare; does not change management.

Chronic thrombo-veno-embolism a complication
of recurrent PE with development of (severe)
pulmonary hypertension

Question 2

What are the vessels that provide oxygen to the lung parenchyma?

Answer 2

 The bronchial vessels
 The airways
 The pulmonary circulation

Question 3

Mortality of VTE

Answer 3

Within 30 days of diagnosis:

among all patients: 11.4%
among treated patients: 9.2%
among untreated patients: 25.2

Question 4

What are the components of Virchow’s triad?

Answer 4

 Local trauma to the vessel wall:
Past DVT, fracture, trauma, surgery.

 Stasis in the circulation:
pregnancy, pelvic tumor, operation of abdomen or pelvic
areas, immobilization, prolonged bed rest, congestive
heart failure.

 Hyper-coagulability and increasing
viscosity of the blood
Congenital:
protein S - C deficiency, factor V Leiden factor,
Acquired:
anti-phospholipid syndrome, Troussseau syndrom

Question 5

What are the consequences of pulmonary emobolism and mechanical blockade of pulmonary arterial vascular bed

Answer 5

Increase pressure proximal to embolus causing increase in pulmonary vascular resistance.

A decrease/ cessation of blood flow distal to
embolus causing loss of surfactant, causing hemorrhage.

The cardiac index will fall only if there is a massive embolism occluding more than 50% of the pulmonary vascular bed.

Question 6

What is the effect of atelectasis of the alveoli?

Answer 6

 loss of surfactant (due to reduced perfusion) and
 alveolar hemorrhage due to occluded pulm artery

Question 7

Causes of hypoxemia in pulmonary embolism

Answer 7

 V/Q inequality - mainly
 Shunt
 Increased dead space
 Diffusion impairment in areas with high
flow (reduced transit time)
 Opening up of latent pulmonary artery-vein
anastomoses d/t high pulm artery pressure
 Blood flow infarcted areas

Question 8

Humoral factors of pulmonary embolism

Answer 8

Vasoconstriction and Bronchostriction.

 Platelets in the emboli release – serotonin, prostatagladins, histamine and more
 Reflex vasoconstriction d/t sympathetic nervous system

Question 9

Prevention of DVT/PE

Answer 9

 Medically:
 sc clexan (low molecular weight heparin (LMWH)) (40 mg/1 d)
 Pro/con: once daily, expensive, (no antidote)
 sc low dose heparin (5000 units X 2-3/d)
 Pro/con: Cheap, but 2-3x /day, (antidote available).
 Mechanically:
early mobilization,
treadmill in bed,
elastic stockings

Question 10

Clinical Presentation of Pulmonary Embolism

Answer 10

1. Dyspnea, pleuritic pain and hemoptysis - most common
2. Syncope and hemodynamic instability - usually
   associated with massive P.E.
3. Mimicking indolent pneumonia, CHF, COPD especially in the elderly - least common.
4. Pulmonary hypertension= chr thrombo-embolism; rare
   Severity of PE:
    Massive PE with systemic hypotension
    Moderate to large PE with RV hypokinesia (sub-massive)
    Small to moderate PE with normal RV and blood pressure
    Pulmonary infarction: usually small PE, but exquisitely painful in pleura

Also: hypocapnia/alkalosis, CT scan abnormal

Difficult to diagnose, use probability and ruling out others (negative D-dimers, normal V/Q scan, etc)

Question 11

Therapy for Pulmonary Embolism

Answer 11

If high risk of death:

1. Treat shock if present with fluid and vasopressors
2. Give heparin treatment (prevent further emboli but doesn’t dissolve existing)
3. Warfarin maintenance beginning at day 3-5 until as long as risk factors present-not for pregnant women (LMWH instead)
4. When INR >2 can stop warfarin

For recent hemorrhagic CVA, eye surgery or neurosurgical operation, give FEX. Can also consider filter in IVC but will have pooling in legs.