Makindo Medical Notes

Related Subjects: |Microangiopathic Haemolytic anaemia |Haemolytic anaemia |Immune (Idiopathic) Thrombocytopenic Purpura (ITP) |Thrombotic Thrombocytopenic purpura (TTP) |Haemolytic Uraemic syndrome (HUS) |Thrombocytopenia |Disseminated Intravascular Coagulation (DIC)

Disseminated intravascular coagulation (DIC) is a clinicopathological syndrome that complicates a range of illnesses and is characterised by systemic activation of pathways leading to and regulating coagulation, which can result in the generation of fibrin clots that may cause organ failure with concomitant consumption of platelets and coagulation factors that may result in clinical bleeding

About

• DIC "Death is coming" seen in 1% of inpatients usually complicating a serious illness.
• Uncontrolled coagulation and consumption of clotting factors leads to bleeding
• Leads to massive haemorrhage and organ failure and prognosis is poor

Aetiology

• Clotting factors are consumed due to excess thrombin formation due to formation of microvascular thrombi
• Consumption of fibrinogen as it is converted to fibrin with clotting and fibrinolysis.
• Platelets get caught within clots

Clinical

• Seen in critically ill patients
• Bleeding from IV and arterial sites
• Bleeding from the mouth, GI tract, Haematuria or Epistaxis
• Intracerebral haemorrhage, Bleeding from Surgical wounds

Important causes of DIC

• Trauma and tissue damage e.g. burns, snake bites
• Severe liver failure, Toxic and immunological insults
• Bacterial Gram-negative sepsis, Gram-positive infections, Rickettsia
• Viral: HIV, CMV, hepatitis, Fungal: Histoplasma, Parasitic: malaria
• Malignancy: Acute Promyelocytic leukaemia / M3, haematology, Metastases
• Obstetric: Amniotic fluid embolism, Placental abruption, Pre-eclampsia
• ABO transfusion incompatibility, Recreational drugs
• Vasculitis, Inflammatory bowel disease, Vascular aneurysm

There is low platelets prolonged prothrombin time, APTT and bleeding time

Investigations * markers of severity

• Prolonged Prothrombin time* (> +6 sec) APTT and Bleeding time
• Reduced Fibrinogen* (< 1 g/L)
• Reduced Factor VIII
• Reduced VWF
• Reduced platelets* (< 50 x10⁹/L)
• Elevated FDPs* due to fibrinolysis (High)
• Fragmented red cells - schistocytes due to microangiopathic haemolytic anaemia
• CXR - ARDS picture may be seen

Differential

• TTP and HUS
• Severe malignant hypertension
• Preeclampsia, HELLP syndrome
• Microangiopathic haemolytic anaemia

Scoring systems: Scoring system for overt DIC

• Risk assessment: Does the patient have an underlying disorder known to be associated with overt DIC?
  • If yes: proceed
  • If no: do not use this algorithm
• Order global coagulation tests (PT, platelet count, fibrinogen, fibrin related marker)
• Score the test results
  • Platelet count (>100x10⁹/l = 0, <100x10⁹/l = 1, <50x10⁹/l = 2)
  • Elevated fibrin marker (e.g. D-dimer, fibrin degradation products) (no increase = 0, moderate increase = 2, strong increase = 3)
  • Prolonged PT (<3 s = 0, >3 but <6 s = 1, >6 s = 2)
  • Fibrinogen level (>1 g/l = 0, <1 g/l = 1)
• Calculate score:
  • =5 compatible with overt DIC: repeat score daily
  • <5 suggestive for non-overt DIC: repeat next 1-2 d

Management requires Haematology consult

• Treat the underlying cause. This is the prime action that should be undertaken.
• The PT/APTT and APTT and platelet count identify the level of coagulation factor consumption. Fibrinolysis can be assessed with D Dimers. A reduction in the platelet count or a clear downward trend at subsequent measurements is a sensitive (though not specific) sign of DIC. The PT or aPTT is prolonged in about 50-60% of cases of DIC at some point during the course of illness.
• Blood component therapy should not be instituted on the basis of laboratory results alone but is indicated in patients with active bleeding, in those requiring an invasive procedure and those who are otherwise at risk for bleeding complication
• Platelets: Threshold depends on the clinical state of the patient. If bleeding and platelet count of <50x10⁹/l. In non-bleeding patients, a threshold of 10x10⁹/l is adopted based on randomised controlled trials. The suggested initial dose of platelets is one adult UK dose (>240x10⁹).
• Fresh frozen plasma: may be necessary to correct the coagulation defect. Initial doses of 15 ml/kg of fresh frozen plasma (FFP) are suggested.
• Fibrinogen: administration of purified fibrinogen concentrates or cryoprecipitate. A dose of 3g would be expected to raise plasma fibrinogen by around 1g/l. This can be given as approximately 4 U of FFP, two cryoprecipitate pools (10 donor units) or as 3 g of a fibrinogen concentrate. The response to component therapy should be monitored both clinically and by repeating platelet counts and coagulation tests following administration.
• In cases of DIC where thrombosis predominates, such as arterial or venous thromboembolism, severe purpura fulminans associated with acral ischaemia or vascular skin infarction therapeutic doses of heparin should be considered. In critically ill, non-bleeding patients with DIC, prophylaxis for venous thromboembolism with prophylactic doses of heparin or low molecular weight heparin is recommended

References

• Guidelines for the diagnosis and management of disseminated intravascular coagulation. British Society for Haematology