Lecture 27

Question 1

DIC

Answer 1

complex acquired disorder of hemostasis that commences with widespread activation of blood coagulation within the microcirculation and may progress to sustained fibrinolysis and hemorrhage

Question 2

Major mechanisms by which DIC can be triggered (2)

Answer 2

release of tissue factor (3) or tissue factor like procoagulant
widespread endothelial injury

Question 3

Some examples of disease conditions that commonly trigger DIC(5)

Answer 3

Bacteria-gram neg (endotoxin) and gram pos
helminths
protozoa (sarcocystis)
virus
neoplasia

Question 4

Phase 1 of DIC clinical signs

Answer 4

hypercoagulability- compensated or sub clinical phase

coag cascade counterbalanced with anticoagulants

Question 5

Phase 2 of DIC. Why? What can it cause

Answer 5

microthrombosis-sustained thrombin generation->consumption of anticoags->widespread coag in the microcirculation->clinically shown or decompensated DIC
-Can cause fragmentation trauma to RBC because of fibrin strands->schistocytes, intra and extra vascular hemolysis

Question 6

Clinical signs of phase 2 DIC

Answer 6

shock, organ failure, dyspnea, cyanosis

Question 7

What happens in Phase 3 of DIC and why?

Answer 7

continued consumption of platelets and coag factors->thrombocytopenia and inadequate coag factor activity->hypOcoagulability= hemorrhagic phase

Question 8

what is the hemorrhage in phase 3 enhanced by?(2)

Answer 8

FDP fibrin degradation products

defects in both primary and secondary hemostasis

Question 9

What are characteristic features of bleeding due to DIC?

Answer 9

mucosal and or cutaneous petechiae and ecchymoses, epistaxis, deep hematomas, bleeding into body cavities

Question 10

why are systemic inflammatory responses and cytokine cascades activated in DIC?

Answer 10

activated coag factors in general are pro inflammatory

factor 10,2,1 activate endothelial cells->synthesis of pro inflammatory cytokines

Question 11

why do many animals in DIC develop shock?

Answer 11

factor 12 activates kallikrein-kinin system->generation of kinins->vasodilation and inc vascular permeability->systemic hypotension and shock

Question 12

Which phase of DIC is largely responsible for high morb/mort?

Answer 12

microthrombosis phase 2

Question 13

What post mortem lesions might you find?

Answer 13

microscopic thrombi in tissues
edema , congestion, hemorrhage, ischemic necrosis
Note: microthrombi may lyse within 3 hours of death

Question 14

Some examples of localized forms of DIC?

Answer 14

bilateral renal cortical necrosis
hemorrhagic adrenocortical necrosis
gangrene of extremities