2. •
•
•
•
Thrombus: an aggregation of blood factors, primarily platelet and
fi
brin with entrapment of cellular element, frequently causing
vascular obstruction at the point of its formation
Thrombosis: formation or presence of a thrombus, e.g.
thrombosis of cerebral vessels, thrombosis of coronary artery.
Embolus: a clot or other plug brought by blood from another
vessel and forced in to a smaller one, thus obstructing the
circulation.
Phelbititis: inflammation of the vein.
591
Firaol R. (MSc)
3. DVT…
•
•
Venous thrombosis: a condition in which blood
clot(thrombus) forms on the wall of the veins
accompanied by inflammation of the vein wall and
some degree of obstructed venous blood flow.
DVT: formation of blood clot(thrombus)in deep veins,
predominantly in the legs.
Firaol R. (MSc) 592
4. Risk Factors for Deep Vein Thrombosis (DVT) and
Pulmonary Embolism
Endothelial damage
Trauma
Surgery
Pacing wires
Central venous catheters
Dialysis access catheters
Local vein damage
593
Firaol R. (MSc)
5. Risk Factors for Deep Vein Thrombosis (DVT)…
–
–
–
–
Venous stasis
Bed rest or immobilization
Obesity
History of varicosities
Spinal cord injury
Firaol R. (MSc) 594
6. Risk Factors for Deep Vein Thrombosis (DVT)…
Altered blood coagulation
Cancer
Pregnancy
Antithrombin III deficiency
Polycythemia –Excess RBC thicken the blood
Septicemia
Firaol R. (MSc) 595
7. Pathophysiology
•
1.
2.
3.
•
Although the exact cause of venous thrombosis
remains unclear, three factors, are believed to
play a significant role in its development:
Stasis of blood (venous stasis)
Vessel wall injury
Altered blood coagulation
At least two of the factors seem to be necessary
for thrombosis to occur.
596
Firaol R. (MSc)
8. Pathophysiology…
•
•
•
•
1. Venous stasis occurs when blood flow is reduced.
As in heart failure or shock
When veins are dilated as with some medication
therapies
When skeletal muscle contraction is reduced, as in
immobility, paralysis of the extremities, or
anesthesia
Moreover, bed rest reduces blood flow in the legs by
Firaol R. (MSc) 597
9. Pathophysiology…
•
•
2. Damage to the intimal lining of blood vessels
creates a site for clot formation
Direct trauma to the vessels, as with fractures or
dislocation, diseases of the veins
Chemical irritation of the vein from intravenous
medications or solutions, can damage veins.
Firaol R. (MSc) 598
10. Pathophysiology…
3. Increased blood coagulability occurs most
commonly
In patients who have been abruptly withdrawn from
anticoagulant medications.
Oral contraceptive use and several blood dyscrasias
(abnormalities)
Firaol R. (MSc) 599
11. Pathophysiology…
•
•
•
When a thrombus develops initially in the veins as a result
of stasis or hypercoagulability but without inflammation,
the process is referred to as phlebothrombosis
Venous thrombosis can occur in any vein but occurs more
in the veins of the lower extremities
The superfi
cial and deep veins of the extremities may be
affected.
Firaol R. (MSc) 600
13. Clinical manifestations
•
•
•
Deep Veins
Edema and swelling of the extremity
The affected extremity may feel warmer than
unaffected extremity
Tenderness, which usually occurs later, is
produced by inflammation of the vein wall
602
Firaol R. (MSc)
14. Clinical manifestations…
Superficial Veins
Thrombosis of superf i
cial veins produces pain or
tenderness, redness, and warmth in the involved area
The risk of the superfi
cial venous thrombi becoming
dislodged or fragmenting into emboli is very low
because most of them dissolve spontaneously.
Firaol R. (MSc) 603
16. Assessment and Diagnostic Findings
History and physical examination
Doppler ultrasound of leg and pelvic veins
MRI
Blood laboratory studies
Homans' sign has been used historically to
assess for DVT.
Firaol R. (MSc) 605
17. Homans' sign
Firaol R. (MSc) 606
In performing this test the patient will need to actively extend his knee.
Once the knee is extended the examiner raises the patient’s straight leg
to 10 degrees, then passively the foot and squeezes the calf with the
other hand.
Deep calf pain and tenderness may indicate presence of DVT.
19. Medical Management
•
•
The objectives of treatment for deep vein
thrombosis are to prevent the thrombus from
growing and fragmenting and to prevent recurrent
thromboembolism.
Anticoagulant therapy (administration of a
medication to delay the clotting time of blood,
p revent the f o rm a tio n o f a thro m b u s in
postoperative patients.
608
Firaol R. (MSc)
20. Medical Management…
•
•
Unfractionated heparin is administered
subcutaneously to prevent development of DVT, or
by intermittent or continuous IV infusion for 5 to 7
days to prevent the extension of a thrombus and
the development of new thrombi.
Oral anticoagulants, such as warfarin (Coumadin),
are administered with heparin therapy.
Firaol R. (MSc) 609
21. Medical Management…
•
•
Thrombolytic therapy: is given within the fi
rst 3
days after acute thrombosis.
Surgery is necessary for DVT when anticoagulant
or thrombolytic therapy is contraindicated .
Firaol R. (MSc) 610
