Disorders of Circulation - DIC, Infarction + Shock

Question 1

Etiologies related to DIC?

Answer 1

Diffuse endothelial damage due to:

1. Extensive tissue injury (Ex: burns)
2. Neoplasia
3. Systemic immunologic rxns (Ex: anaphylaxis from snake bite)
4. Sepsis

Question 2

What happens in the first stage of DIC?

Answer 2

Increased blood coagulation in microvessels, fibrin clots (fibrinoembolism)

Question 3

What happens in the 2nd stage of DIC?

Answer 3

• Decreased thrombocytes, fibrinogen and prothrombin in the blood
• Consumption coagulopathy

-Bleeding diathesis and hemorrhagic syndrome develops

Question 4

Signs of __________ can be seen in DIC

Answer 4

Hypoxia, infarction, hemorrhage

Question 5

What is an example of sepsis that can lead to DIC?

Answer 5

1. Canine hepatitis
2. Blue tongue
3. Hog cholera

Question 6

What happens in the 3rd stage of DIC?

Answer 6

Fibrinolysis activation (breaking down clots) and more severe hemorrhagic syndrome

Question 7

What is infarction?

Answer 7

Localized area of ischemic/coagulative necrosis caused by occlusion of arterial supply or venous drainage

Question 8

Infarction is most often due to:

Answer 8

Thrombosis, embolism, or vascular occlusion from twisting of a vessel

Question 9

Gross appearance of infarction?

Answer 9

• wedge shaped
• Early stage: ill defined and red
• Later stage: may become pale

Question 10

Factors that influence the development of an infarct? (4)

Answer 10

1. Nature of vascular supply
2. Rate of development of occlusion
3. Vulnerability of affected organ to hypoxia
4. Oxygen content of blood @ time of infarction

Question 11

_________ infarcts are usually intensively hemorrhagic

Answer 11

Venous

Question 12

Characteristics of an arterial infarct?

Answer 12

-PALE
-WITHOUT blood
-Red zone in periphery
-Initially hemorrhagic
-Occurs in solid organs (Ex: kidney)

Question 13

Characteristics of a venous infarct?

Answer 13

-RED
-contains blood
-ACUTE
-intensively hemorrhagic
-Occurs in organs with dual blood supply (Ex: intestines

Question 14

________ infarcts usually occur in solid organs

Answer 14

Pale, arterial

Question 15

________ infarcts usually occur in organs with dual blood supply

Answer 15

Red, venous

Question 16

Microscopically, an infarct is ________

Answer 16

A focal area of coagulative necrosis

Question 17

What does infarct repair look like?

Answer 17

-scar tissue replaces parenchyma

-fibrous tissue contraction leaves a depression or indentation on the surface of the organ

Question 18

Septic infarcts occur mostly from _________

Answer 18

Septic, bacterial infected thromboembolus

Question 19

Venous infarction is often due to _________

Answer 19

Twisting of vessels (intestinal volvulus)

occasionally due to obstruction of portal vein or vena cava

Question 20

With volvulus, the _______ outflow is obstructed while the _______ flow is maintained

Answer 20

Venous, arterial

Question 21

Acute blockage of portal venous system can lead to?

Answer 21

Shock and intestinal venous infarction

Question 22

What is an example of a venous obstruction leading to infarction of the caudal vena cava IN DOGS?

Answer 22

• Severe heartworm dz
• Tumor invasion

Question 23

What is an example of a venous obstruction leading to infarction of the caudal vena cava IN RUMINANTS?

Answer 23

Rupture of hepatic abscesses

travels to caudal vena cava causing blockage

resulting in acute right sided heart failure and death

Question 24

Causes of pulmonary arterial thrombosis?

Answer 24

1. Pneumonia
2. Parasites
3. Hypercoagulability
4. Liver abscess rupture into vena cava - thromboembolism to lungs

Question 25

Shock is a clinical state of __________

Answer 25

Cardiovascular collapse

Question 26

Shock is characterized by?

Answer 26

1. Acute reduction of blood volume 2. Inadequate perfusion of cells and tissues (Reduced cardiac output)

Question 27

What tissues/organs are most susceptible to hypoxia?

Answer 27

Brain and heart

Question 28

What are the end results of shock?

Answer 28

-hypotension -impaired tissue perfusion -cellular hypoxia -can lead to DIC and multi-organ failure

Question 29

Pathogenesis of shock?

Answer 29

1. Body tries to maintain blood supply to brain and heart first 2. Impaired tissue perfusion leads to anaerobic glycolysis 3. Lactic acidosis 4. Lysosomal damage and widespread cell injury

Question 30

What are the main types of shock that can occur?

Answer 30

1. Cardiogenic shock 2. Hypovolemic shock 3. Vasculogenic (maldistribution) shock

Question 31

Cardiogenic shock can result from _______

Answer 31

1. Reduced cardiac filling Ex: Cardiac tamponade 2. Reduced cardiac emptying Ex: massive pulmonary embolism 3. Ruptured chordae tendinae

Question 32

Fluid loss due to _________ can lead to hypovolemic shock

Answer 32

Hemorrhage, burns, vomiting, diarrhea, dehydration

Question 33

What is vasculogenic shock?

Answer 33

Decrease in peripheral vascular resistance, pooling of blood in peripheral tissues

Question 34

Vasculogenic shock results from __________

Answer 34

Vasodilation

Question 35

Anaphylaxis can lead to __________ shock

Answer 35

Vasculogenic due to release of vasoactive amines and vasodilation

Question 36

Pathogenesis of septic shock?

Answer 36

1. Endotoxins released from bacT 2. Injury to endothelial cells by LPS 3. Activation of complement and WBCs 4. Coagulation activation (DIC) 5. cytokine release 6. Thrombosis and vasodilation 7. Tissue ischemia

Question 37

What happens in the reversible stage of shock?

Answer 37

1. Blood redistribution to brain and heart 2. Vasoconstriction 3. Fluid conservation by kidney

Question 38

How does the skeletal muscle appear during shock?

Answer 38

Pallor - pale ** bc blood is redistributed to brain and heart and not muscle

Question 39

What is the most common type of vasculogenic shock?

Answer 39

Septic shock- from bacT causing vasodilation