Disseminated Intravascular Coagulation - Pediatric Critical Care - Lecture Slides, Slides of Pediatrics

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Disseminated Intravascular Coagulation

DIC

• An acquired syndrome characterized by systemic intravascular coagulation
• Coagulation is always the initial event.
• Most morbidity and mortality depends on extent of intravascular thrombosis
• Multiple causes

Vascular Endothelium

• Vascular endothelium

expresses :

• Thrombomodulin
• Tissue Plasminogen Activator
• Tissue thromboplastin/Tissue factor

Coagulation

• Intrinsic Pathway
• Extrinsic Pathway
• Common Pathway
• Contact Pathway
• Tissue Factor Pathway
  • Primary factor in DIC

Anticlotting Mechanisms

• Protein C
  • Activated by Thrombin/Thrombomodulin
  • Anticoagulant and fibrinolytic activity.
  • Vitamin K and Protein S are cofactors
• Protein S

Fibrinolytic System

• Plasmin
  • Produced from Plasminogen by Tissue Plasminogen activator (TPA)
  • Degrades Fibrin and Fibrinogen (Fibrin degradation products, FDP)
  • Degrades Factors V, VIII, IX, XI, and XII.
  • Activity is inhibited by Antiplasmin.

Pathophysiology of DIC

• Activation of Blood Coagulation
• Suppression of Physiologic Anticoagulant Pathways
• Impaired Fibrinolysis
• Cytokines

Pathophysiology of DIC

• Activation of Blood Coagulation
  • Tissue factor/factor VIIa mediated thrombin generation via the extrinsic pathway - complex activates factor IX and X
  • TF
    • endothelial cells
    • monocytes
    • Extravascular:
      • lung
      • kidney
      • epithelial cells

Pathophysiology of DIC

• Impaired Fibrinolysis
  • relatively suppressed at time of maximal activation of coagulation due to increased plasminogen activator inhibitor type 1

Pathophysiology of DIC - Cytokines

• Cytokines
  • IL-6, and IL-1 mediates coagulation activation in DIC
  • TNF-α
    • mediates dysregulation of physiologic anticoagulant pathways and fibrinolysis
    • modulates IL-6 activity
  • IL-10 may modulate the activation of coagulation

Inflamation^ Coagulation

Conditions Associated With DIC

• Malignancy
  • Leukemia
  • Metastatic disease
• Cardiovascular
  • Post cardiac arrest
  • Acute MI
  • Prosthetic devices
• Hypothermia/Hyperthermi a - Pulmonary - ARDS/RDS - Pulmonary embolism - Severe acidosis - Severe anoxia - Collagen vascular disease - Anaphylaxis

Conditions Associated With DIC

• Infectious/Septicemia
  • Bacterial
    • Gm - / Gm +
  • Viral
    • CMV
    • Varicella
    • Hepatitis
  • Fungal
• Intravascular hemolysis
• Acute Liver Disease
  • Tissue Injury
    • trauma
    • extensive surgery
    • tissue necrosis
    • head trauma
  • Obstetric
    • Amniotic fluid emboli
    • Placental abruption
    • Eclampsia
    • Missed abortion

Microscopic findings in DIC

• Fragments
• Schistocytes
• Paucity of platelets

Laboratory Tests Used in DIC

• D-dimer *
• Antithrombin III *
• F. 1+2*
• Fibrinopeptide A*
• Platelet factor 4*
• Fibrin Degradation Prod
• Platelet count
• Protamine test
  • Thrombin time
  • Fibrinogen
  • Prothrombin time
  • Activated PTT
  • Protamine test
  • Reptilase time
  • Coagulation factor levels

*Most reliable test