DIC

Question 1

Define DIC.

Answer 1

It is a disorder of hemostasis resulting from generation of excess thrombin activity in circulating blood. Always a serious complication of another underlying disorder

Question 2

What is the pathogenesis of DIC.

Answer 2

-It is believed that Tissue factor triggers almost all DIC

Question 3

What are the defense mechanisms against proagulation?

Answer 3

1. Antithrombin
2. Protein C and S system (activated by thrombin/thrombomodulin complex)
3. TFPI
4. Fibrinolytic system
5. Fibrinogen depletion
6. formation of fibrin monomer-fibrinogen complexes that are soluble

Question 4

What laboratory values would you find in the diagnosis of DIC?

Answer 4

1. Thrombocytopenia
2. increased D dimer (only formed if thrombin and XIIIa active+plasmin)
3. increase in fibrin monomer- positive protamine test
4. Low or normal fibrinogen
5. PTT and PT are variable

Question 5

What are the causes of disseminated DIC?

Answer 5

1. Infection: bacterial gram neg, rickettsia, viral hemorrhagic fevers, malaria, fungemia
2. Obstetrical conditions: abruptio placenta, amniotic fluid embolism, retained dead fetus, saline abortion, fatty liver of preg, puerperal sepsis
3. Neoplastic disease: acute leukemia, disseminated carcinoma or sarcoma
4. Massive tissue necrosis: brain tissue destruction, heat stroke, fulminant hepatic necrosis, extensive trauma or burns
5. prolonged shock
6. miscellaneous: snake bites

Question 6

What are localized causes of DIC?

Answer 6

1. kasabach-Merritt-giant hemangioma
2. phlegmasia cerulean dolens-huge blue leg-rare severe DVT
3. Aortic aneurysm
4. hyperacute renal transplant rejection
5. misc

Question 7

What are the consequences of DIC?

Answer 7

1. bleeding due to low platelets and coag factors from increased consumptions and increased secondary fibrinolysis
2. ischemic tissue damage due to fibrin deposition in microvasculature
3. stroke, acute MI due to microvascular thrombosis
4. fragmentation hemolytic anemia from fibrin deposition in small blood vessels and fracture of RBCs by fibrin strands

Question 8

How is DIC managed?

Answer 8

1. REMOVE UNDERLYING CAUSE
2. replacement therapy for bleeding: cryoprecipitate (fibrinogen and FVIII), fresh frozen plasma (other procoags)
3. heparin - to improve response to factor replacement if bleeding unresponsive to #2
4. heparin - for thrombosis or ischemia
5. Heparin contraindicated if: cause of DIC removable, no bleeding or thrombotic complications, bleeding complications easily controlled by factor replacement

Question 9

What procoagulant and inflammatory mediators are generated by monoctyes and macrophages as trigger mechanisms of DIC?

Answer 9

1. Tissue Factor

2. Different interleukins, TNF

Question 10

What procoagulant mediators are produced by endothelial cells as trigger mechanisms in DIC?

Answer 10

1. Tissue factor
2. decreased thrombomodulin
3. increased PAI