Hemostasis

Question 1

Define edema

Answer 1

Accumulation of interstitial fluid in tissues, including subcutaneous tissues and body cavities

Question 2

What is anasarca?

Answer 2

Very severe generalized edema

Question 3

What is the most common cause of lymphatic obstruction (lymphadema)?

Answer 3

Post-surgical or post-radiation therapy scarring/removal of lymph channels.

Question 4

Name 4 general pathopysiologic causes of edema

Answer 4

1. Increased capillary hydrostatic pressure due to arterial dilation or impaired venous return
2. Reduced plasma osmotic pressure due, possible due to excessive loss of albumin (nephrotic syndrom, protein-losing enteropathy, malnutrition, liver disease/cirrhosis)
3. Lymphatic obstruction (lymphedema) due to inflammatory, neoplastic, or iatrogenic (surgery, radiation) processes
4. Sodium (and water) retention due to excessive salt intake or acute reduction in renal function

Question 5

Define hyperemia. Where does it occur?

Answer 5

Increase in blood volume within a tissue due to increased blood flow and arteriolar dilation. Hyperemia is an active process that commonly occurs at the site of inflammation or in exercising skeletal muscles.

Question 6

Define congestion. Where does it occur?

Answer 6

Increase is blood volume in a tissue due to impaired/decreased outflow of venous blood (passive process).

Examples:

Systemic: liver and lung congestion due to heart failure

Local: obstruction of superior saggital sinus

Question 7

List the general steps in primary hemostasis (5)

Answer 7

1. Platelet adhesion
2. Platelet shape change
3. Platelet granule release
4. Recruitment
5. Aggregation and formation of hemostatic plug

Question 8

Name the general steps in secondary hemostasis (4)

Answer 8

1. Tissue factor release
2. Phosphlipid complex expression
3. Thrombin activation
4. Fibrin polymerization

Question 9

What does Prothrombin time (PT) measure?

Answer 9

Extrinsic pathway + common pathway

Question 10

What does Activated Partial Thromboplastic time (aPTT) measure?

Answer 10

Intrinsic pathay + common pathway

Question 11

Hemophilia A features a defect in what clotting factor? Hemophilia B?

Answer 11

A: Factor VIII

B: Factor IX

Question 12

Which clotting factors are dependent on vitamin K?

Answer 12

Factors 2, 7, 9, 10

Question 13

Name the hemodynamic disease matching each of the following bleeding disorder mechanisms or descriptions:

1. Factor 9 deficiency
2. General factor deficiencies or dysfunction
3. Inherited defect in platelets causing a deficiency of gpIIb/IIIa expression on platelet membranes
4. Too few platelets
5. Vitamin C deficiency leading to vessel fragility (collagen synthesis issue)
6. von Willebrand factor deficiency or dysfunction
7. Platelet and clotting factor consumption due to systemic clotting followed by systemic bleeding
8. Deficiency of factors 2, 7, 9, 10
9. Factor 8 deficiency

Answer 13

1. Hemophilia B
2. Liver disease
3. Glanzmann’s thrombasthenia
4. Thrombocytopenia
5. Scurvy
6. von Willbrand disease
7. Disseminated Intravascular Coagulation (DIC)
8. Vitamin K deficiency (or Warfarin therapy)
9. Hemophilia A

Question 14

What is hemorrhagic diathesis?

Answer 14

A predisposition to hemorrhage, even with minimal trauma

Question 15

Define hematoma

Answer 15

Accumulation of blood within a tissue

Question 16

Define and describe: petechial hemorrhage

Answer 16

1-2mm hemorrhage, usually into skin, mucous membranes, or serosal surfaces. Petechiae can be associated with low platelet counts (thrombocytopenia), platelet dysfunction, loss of vascular wall support, or local pressure.

Question 17

Define and describe: purpura

Answer 17

>3mm hemorrhage, usually into skin, mucous membranes, or serosal surfaces. Purpura can be associated with low platelet counts (thrombocytopenia), platelet dysfunction, loss of vascular wall support, or local pressure.

Question 18

Define and describe: ecchymosis

Answer 18

>1-2cm subcutaneous hematoma. Known more commonly as a ‘bruise’. Associated with trauma.

Question 19

Name and describe 4 mechanisms for that inhibit thrombosis

Answer 19

1. Heparin-like molecules are bound by Antithrombin III (atIII). The atIII-heparin complex binds thrombin, inactivating it. The atIII-heparin complex also inactivates factors 9a and 10a.
2. Tissue factor pathway inhibitors expressed on the surface of vascular endothelial cells inactivates 7a-TF complexes
3. Thrombin activates thrombin receptors expressed on vascular endothelial cells, increasing endothelial cell expression/realease of t-PA, which activates the fibrinolytic cascade. Endothelial cells also increase expression of PGI2, NO, and adenosinediphosphatase, all of which inhibit platelet aggregation.
4. Thrombin binds thrombomodulin, a receptor expressed on the surface of vascular endothelial cells. The thrombin-thrombomodulin complex activates protein C, which (via protein S), deactivates factors 5a and 8a.

Question 20

What is Factor 5 Leiden?

Answer 20

• Most common inherited predisposition to thrombosis
• Via single point mutation in the cleavage site on factor V for protein C
• Activated protein C, with protein S, degrades factors 5a and 8a, shutting down the normal clotting cascade.
• Severity depends on number of defective alleles inherited (more alleles increases severity up to 50x risk for thrombosis)

Question 21

What are antiphospholipid antibodies? How are they tested for?

Answer 21

• Acquired autoantibodies against phospholipid complexes associated with thrombosis
• Lab testing: lupus anticoagulant and anti-cardiolipid antibodies
• Inhibit clotting in vitro (longer clotting time test); promote clotting in vivo (increased risk of thrombosis)

Question 22

What are Lines of Zahn?

Answer 22

Laminations of alternating layers of platelets, fibrin, and RBCs characteristic of thrombosis.

Question 23

What is Virchow’s Triad in Thrombosis?

Answer 23

Three primary abnormalities that lead to thrombus formation:

1. Endothelial injury
2. Abnormal blood flow
3. Hypercoagulability

Question 24

What is stasis?

Answer 24

Slow of sluggish flow of blood. Increases risk of thrombosis due to decreased washout of clotting factors and decreased inflow of clotting factor inhibitors.

Question 25

What is a cardiac mural thrombus?

Answer 25

A thrombus attached to the heart wall, usually at or near the site of MI. Decreased contraction contributes to abnormal flow near this site, increasing the risk of thrombus formation.

Question 26

Name 5 types/sources of emboli

Answer 26

1. Thrombus (thromboembolism) 2. Fat, often due to long bone fractures, soft tissue trauma, and burns 3. Air - obstetric procedures, chest wall injuries, decompression sickness 4. Amniotic fluid - delivery 5. Tumor

Question 27

What is name for a thrombotic mass attached to a heart valve?

Answer 27

vegetation

Question 28

What is a paradoxical embolism?

Answer 28

an embolism that travels through a heart defect (such as a patent foramen ovale), producing an obstruction on the arterial side of systemic circulation

Question 29

What is the most common thrombotic source of pulmonary embolism (PE)?

Answer 29

Deep vein thrombosis (DVT)

Question 30

What is a **saddle embolus**?

Answer 30

An embolus lodged at a bifurcation of the pulmonary arteries.

Question 31

What is a red infarct? Where is it more likely to occur?

Answer 31

A hemorrhagic infart, usually occurrin in loose tissues or tissues with secondary circulation. May also occur in cases where flow is re-established post-infarct, or with venous occlusions.

Question 32

What is a white infarct? Where are they most likely to occur?

Answer 32

Anemic infarct (no blood). Occur primarily in solid organs with end-arterial circulation. Examples include kidneys and spleen.

Question 33

What is the difference between a hemorrhagic infarct and a hematoma?

Answer 33

* **Hematoma:** blood is collected to form a solid mass * **Hemorrhagic infarct:** Blood is intermixed with necrotic tissue

Question 34

Define and describe the mechanism behind **Disseminated Intravascular Coagulation (DIC)**

Answer 34

* Initial widespread clotting resulting in organ ischemia, followed by bleeding tendencies * Associated with severe illness (burns, sepsis, trauma, cancer, etc) * Initial clotting leads to comsumptive coagulopathy. The significant decrease in available clotting factors and platelets leads to bleeding tendency.

Question 35

Define **shock**

Answer 35

Systemic hypoperfusion caused by: 1. Reduced cardiac output (MI, PE, arrhythmia, etc) 2. Decrease in effective circulating blood volume (hemorrhage, hypotension, etc)

Question 36

Name and describe 3 major types of shock

Answer 36

1. Cardiogenic - failure of myocardial pump 2. Hypovolemic - inadequate blood or plasma volume 3. Septic - peripheral vasodilation and pooling of blood seconary to overwhelming microbial infection.

Question 37

What is neurogenic shock?

Answer 37

Interruption of sympathetic vasomotor output due to spinal cord injury. Results in arteriolar/venous dilation and decrease cardiac output.

Question 38

Define anaphylactic shock

Answer 38

IgE-mediated hypersensitivity response, leading to systemic vasodilation, leading to shock

Question 39

Name and describe the 3 major phases of shock

Answer 39

1. Nonprogressive: tachycardia, peripheral vasoconstriction, renal fluid conservation. Perfusion of organs maintained. 2. Progressive: tissue hypoxia and lactic acidosis due to widespread tissue hypoperfusion 3. Irreversible: cellular and organ injury preventing survival (ischemia and massive lactic acidosis)

Question 40

What type(s) of shock present with the following? * Hypotension, tachycardia, tachypnea * Cool, clammy, cyanotic skin

Answer 40

Hypovolemic or Cardiogenic shock

Question 41

What type(s) of shock present with the following? * Hypotension, tachycardia, tachypnea * Warm and flushed skin (initially)

Answer 41

Septic shock (Initial warm/flushed skin is due to peripheral vasodilation)

Question 42

Characterize the infection pattern in septic shock

Answer 42

Most often gram-positive bacteria, followed by gram-negative bacteria and fungi