DISSEMINATED INTRAVASCULAR COAGULATION

Definition: unregulated thrombin explosion which leads to widespread microvascular thrombosis, tissue ischemia and organ damage, and excess plasmin generation which results in systemic fibrinogenolysis. Bradykinin release may also lead to hypotension, shock.

The thrombin explosion: tissue factor complexes with factor VII which activates the factor VIII/IX complex, which activates the factor X/V complex, forming thrombin. This is normally regulated by antithrombin and thrombomodulin/protein C.

Causes of DIC:

1. Infection- most common cause, may be GN or GP

2. Obstetric complication- placental separation and amniotic fluid embolism result in placental TF release.

3. Trauma, burn, heatstroke, lightning strikes- result in endothelial damage and massive TF release.

4. Transfusion of ABO incompatible RBCs- complement activation leads to endothelial damage.

5. Liver disease

6. Malignancy- invasion of tissues, activation of leukocytes, or specific procoagulant

Diagnosis: CLINICAL with laboratory confirmation

1. Clinical scenario

2. Plasmin generation- spontaneous bruising, petechiae, GI bleed, respiratory bleed, persistent bleeding at venupuncture sites or surgical wounds, IC bleed.

3. Thrombin generation- ARF, coma, liver failure, respiratory failure, skin necrosis, gangrene, venous thromboenbolism

4. Cytokine generation- tachycardia, hypotension, edema.

5. LABORATORIES-

a. thrombin generation- thrombocytopenia, PT(abn in 70%), PTT(abn in 50%), FBGN(low in <50%)

b. plasmin generation- FSP or D-Dimer

c. peripheral smear

Treatment:

1. TREAT UNDERLYING CAUSE

2. Vitamin K- 10mg SC QD X 2 days

3. IF active bleeding or invasive procedure- platelets(1U/10kg), FFP(15 ml/kg), follow DIC panel to document correction

4. Heparin- unclear benefit

5. Natural inhibitors(antithrombin, protein C)- some evidence for benefit in animal models

6. Synthetic inhibitors(gabexate mesylate; inhibits both thrombin and plasmin)- no controlled trials

Baglin. BMJ. 1996, 312: 683-7