Disseminated intravascular coagulation (CH) Flashcards
Define DIC.
Acquired syndrome characterised by activation of coagulation pathways, resulting in formation of intravascular thrombi and depletion of platelets and coagulation factors
What can trigger DIC?
Certain disease states that trigger systemic activation of coagulation may lead to DIC
Major trauma, organ destruction, sepsis or severe infection, severe obstetric disorders, malignancies, major vascular disorders, severe toxic/immunological reactions
What can DIC lead to?
Thrombi may lead to vascular obstruction/ischaemia and multi-organ failure
List some causes of DIC. (6)
- sepsis
- trauma e.g. surgery
- malignancy
- obstetric disorder
- pancreatitis
- transfusion
What is acute DIC?
- sudden-onset bleeding
- thrombosis
- –> hypoperfusion, infarction, end-organ damage, depletion of platelets and coagulation factors
What is chronic DIC?
- process is identical as acute
- occurs at a slower rate with time for compensatory responses
- less likelihood of bleeding but still hypercoagulable state where thrombosis can occur
What types of conditions is acute DIC more common with?
Rapid-onset underlying conditions e.g.
- trauma
- sepsis
- blood transfusions
What types of conditions is chronic DIC more common with?
Less acute disorders e.g. malignancy
What actually happens in DIC?
- haemostasis = out of control
- too much clotting - coagulation in vessels, uses up platelets and coagulation factors –> organ ischaemia
- too little clotting –> bleeds with slightest injury
Describe the pathophysiology of DIC.
- increased thrombin –> increased fibrinogen –> fibrin conversion
- fibrin deposited in vessels –> organ failure + microangiopathic haemolytic anaemia (RBCs become fragmented)
- decreased production of plasmin (degrades fibrin) + activated protein C (anti-inflammatory)
- increased thrombin –> simultaneously activates fibrinolysis –> bleeding into subcutaneous tissues, skin and mucus membranes
What are the clinical features of DIC?
- confusion
- dyspnoea
- signs of circulatory collapse - tachycardia, hypotension, oliguria
- systemic signs of thrombosis - purpura fulminans, gangrene, acral cyanosis
- acute DIC - petechiae, purpura, ecchymoses
- chronic DIC - signs of DVT or arterial thrombosis, superficial venous thrombosis; without varicose veins
What are the clinical features of acute DIC? (1+4)
Bleeding issues:
- petechiae (<4mm bruises)
- purpura (4-10mm bruises)
- ecchymoses (>10mm bruises)
- epistaxis
What are the clinical features of chronic DIC? (1+2)
Clotting issues:
- signs of DVT
- arterial thrombosis
What are the risk factors for DIC? (5)
- major trauma/burn/organ destruction
- sepsis/severe infection (especially gram -ve sepsis)
- malignancy (release of tissue material/procoagulants like tissue factor or cysteine protease trigger coagulation)
- major vascular disorders (large aortic aneurysms or giant haemangiomas)
- severe toxic or immunological reactions (transfusion, transplant rejection etc)
What are the first-line investigations for DIC? (5)
- platelet count
- PT + APTT
- fibrinogen
- D-dimer/fibrin degradation products
- FBC
What would FBC show in DIC? (2)
- low platelets
- low Hb (microangiopathic haemolytic anaemia)
What would clotting screen show in DIC? (3)
- low fibrinogen
- high D-dimer (fibrinogen degradation products)
- prolonged PT and APTT
What would a blood film show in DIC?
Schistocytes - fragmented RBCs
(Microangiopathic haemolytic anaemia)
What are some differential diagnoses for DIC?
- severe liver failure - normal D-dimer/FDPs
- heparin-induced thrombocytopenia
- idiopathic purpura fulminans - normal D-dimer/FDPs, well-demarcated purple skin lesions
- vitamin K deficiency - bleeding WITHOUT thrombosis
- HELLP syndrome - 28wk after gestation
What does warfarin, aspirin, heparin and DIC do to PT, APTT, bleeding time and platelets respectively?
- warfarin administration: prolonged, normal, normal, normal
- aspirin: normal, normal, prolonged, normal
- heparin: often normal (may be prolonged), prolonged, normal, normal
- DIC: prolonged, prolonged, prolonged, low
What is DIC diagnosis based on? (6)
- presence of 1+ known underlying conditions causing DIC
- plus abnormal global coagulation tests
- decreased platelet count
- increased PT
- elevated fibrin-related marker (D-dimer/fibrin degradation products)
- decreased fibrinogen
What is the management plan for DIC? (3)
- treat underlying disorder
- platelets and coagulation factors in patients with active bleeding/high risk:
- platelet transfusion considered when <20x10^9 or <50x10^9 with active bleeding
- FFP is the preferred method for coagulation factor replacement
- 2nd line: cryoprecipitate to replace fibrinogen (or fibrinogen concentrates)
- anticoagulation - heparin
How do we manage chronic DIC? (2)
- if thromboembolism present - anticoagulation with heparin (not suitable if high bleeding risk, antithrombin needs to be >80%)
- if underlying hyperfibrinolysis - antifibrinolytic agents (aminocaproic acid or tranexamic acid)
What are some complications of DIC? (7)
- acute renal failure (organ ischaemia and haemorrhage, hypovolaemia, hypotension)
- life-threatening haemorrhage (consider recombinant factor VII or tranexamic acid)
- haemothorax
- gangrene and loss of digits
- shock
- ARDS
- severe bleeding complications (cardiac tamponade, haemothorax, intracerebral haematoma)
How does sepsis cause DIC?
Deranged coagulation in sepsis –> microangiopathic clots formed throughout body, using up clotting factors and platelets –> increased risk of bleeding –> DIC
Describe the prognosis of DIC.
High mortality, however in some cases DIC will quickly resolve itself after elimination of the underlying condition
