Thromboembolic Disease & Shock-Parsa

Question 1

Intrinsic pathway of coagulation

Answer 1

Activated by thrombogenic surfaces, even glass

Question 2

Extrinsic pathway of coagulation

Answer 2

• Involves tissue factor

* Requires Vitamin K

Question 3

Common pathway of coagulation

Answer 3

Where intrinsic and extrinsic converge on factor ten (fX)

Question 4

How can you inhibit thrombosis formation?

Answer 4

• Herparin-like molecules
• Thrombomodulin
• Tissue factor pathway inhibitor
• Endothelial cell-derived PGI2

Question 5

How can you activate thrombosis formation?

Answer 5

• Endothelial injury
• Tissue factor
• Platelets
• Platelet-derived TxA2

Question 6

How does aspirin prevent thrombosis?

Answer 6

By blocking platelet aggregation (TxA2 synthesis)

Question 7

How does Coumadin prevent thrombosis?

Answer 7

Acts as an antagonist to Vitamin K which is a coagulation promoter

Question 8

How does Heparin prevent thrombosis?

Answer 8

Inhibits coagulation

Question 9

What is Heparin-Induced Thrombocytopenia (HIT)?

Answer 9

• Heparin binds with platelet factor 4 (PF4) which produces antibodies
• These antibodies bind to platelets and lead to thrombosis

Question 10

How does Plasmin prevent thrombosis?

Answer 10

• Breaks down fibrin (clots)

* Drugs - streptokinase and urokinase

Question 11

How does plasminogen activator (t-PA) prevent thrombosis?

Answer 11

Breaks break down already formed thrombi

Question 12

What is Disseminated Intravascular Coagulation (DIC)?

Answer 12

• The sudden or insidious onset of widespread fibrin thrombi in the microcirculation
• Causes prolonged PT (prothrombin time)/PTT (partial thromboplastin time)

Question 13

How is DIC activated?

Answer 13

• Release of thromboplastic substances into circulation
- Seen on OB complications, trauma and burns
• Widespread injury to endothelial cells
- Seen in G-sepsis

Question 14

What is Microangiopathic Hemolytic Anemia (MAHA)?

Answer 14

The destruction of RBS in small vessels that are partially plugged by abnormal aggregates of fibrin and platelets

Question 15

What is a schistocyte?

Answer 15

A fragmented red cell (resemble helmets)

Question 16

What is an embolus?

Answer 16

• An embolus is a detached intravascular solid, liquid, or gaseous mass that is carried by the blood to a site distant from its point of origin
• It lodges in blood vessels and obstructs the flow of blood

Question 17

Thromboemboli

Answer 17

• Venous side and lodges in lungs

* Arterial side resulting in ischemic changes in hands and feet

Question 18

Paradoxical emboli

Answer 18

Emboli that originate in venous system → right heart and go thru a right-to-left passage (patent foramen ovale) in the wall between atria and ventricles (septal defect)(cause systemic effect).

Question 19

Fat emboli

Answer 19

• From fat alone or hematopoietic cells from bone marrow.
• Due to bone fractures where fatty marrow gets into bloodstream.
• Destination: brain and skin.

Question 20

Atheroma emboli

Answer 20

• Atherosclerotic plaque that embolizes following rupture.

* Example: after an angiogram.

Question 21

Amniotic fluid emboli

Answer 21

• Amniotic fluid during delivery can embolize and kill the mother

Question 22

Gas emboli

Answer 22

• From deep diving (dissolved nitrogen), rapid ascent leads to bubbles that clog up vessels in brain or lungs
• Also from delivery or abortion, accidental trauma in pneumothorax, and injury to chest

Question 23

What is ischemia?

Answer 23

• Inadequate blood supply to a tissue

* Can result in infarction (red of white)

Question 24

Local ischemia

Answer 24

Almost always caused by arterial obstruction due to atherosclerosis, thrombosis and embolism

Question 25

What is ischemia dependent on?

Answer 25

• Collateral circulation
• Rate of development of obstruction
• Tissue susceptibility to ischemia

Question 26

What is shock?

Answer 26

Prolonged systemic hypoperfusion resulting from insufficient cardiac output or reduction in the effective circulating blood volume

Question 27

Hypovolemic shock

Answer 27

• Large reduction in intravascular blood volume

* Causes: diarrhea and vomiting (fluid loss), hemorrhage (blood loss) and burns (plasma loss)

Question 28

Cardiogenic shock

Answer 28

• Pump failure

* Causes: massive pulmonary embolism or massive MI

Question 29

What are the 3 way general vasodilation can occur?

Answer 29

1. Anaphylactic shock
2. Neurogenic shock
3. Septic shock

Question 30

Anaphylactic shock

Answer 30

A severe, allergic Type I Hypersensitivity reaction caused by degranulation of mast cells

Question 31

Neurogenic shock

Answer 31

May occur secondary to spinal cord trauma, brain injury or use of general anesthesia causing loss of vascular tone

Question 32

Septic shock

Answer 32

Caused by infectious agents, usually associated with endotoxin producing Gram- bacilli

Question 33

What are the 3 stages of shock?

Answer 33

1. Compensation
2. Impaired tissue perfusion
3. Decompensation

Question 34

Compensation

Answer 34

• Non-progessive
• Sympathetic reflex
• Increased HR, peripheral vasoconstriction, sweating, rapid shallow breathing, cold, clammy and diminishing urine output

Question 35

Impaired tissue perfusion

Answer 35

• Progressive
• Excessive vasoconstriction impairs tissue perfusion resulting in hypoxia and impaired fluid exchange
• Lots of organs get anoxic

Question 36

Decompensation

Answer 36

• Irreversible

* Complete loss of reflex vasoconstriction, kidney failure, extremely low cardiac output, cerebral hypoxia, and death