Acquired Disorders of Haemostasis Flashcards
What are the 6 types of acquired bleeding disorders?
Vit K deficiency Liver disease Massive transfusion syndrome Disseminated Intravascular Coagulation Iatrogenic Acquired Inhibitors
How can you tell the difference between deficiency or inhibitor acquired bleeding disorders?
activated partial thromboplastin time (APTT) in prolonged in both cases
Test should be repeated after giving patient a 50:50 mix of normal plasma
if there is a significant correction = deficiency
no correction = inhibitor
What factor is affected in liver disease?
Factor 7
Why is the platelet count in liver disease low?
fibrotic liver
increased pressure in the portal system
congestion in spleen
platelets in spleen
What are the Vit K dependent factors?
Factor 2, 7, 9 and 10
What enzyme recycles Vit K to its co factor again and is the target of warfarin?
Vitamin K reductase
What are the causes of Vitamin K deficiency?
Obstructive jaundice
Prolonged nutritional deficiency
Broad spectrum antibiotics - affects flora, the source of Vit K
Neonates (classical 1-7 days) - causes haemorrhagic disease
How does bile cause Vit K to be absorbed?
Because it is a fat soluble vitamin
What is cirrhotic coagulopathy?
bleeding disorder due to the fact that the liver synthesises clotting factors
increased risk of severe bleeds (e.g. GI bleeds) from invasive procedures/surgery
What impaired haemostatises can occur in liver disease?
Thrombocytopenia - splenic congestion
Platelet dysfunction - especially in alcoholics by poisoning bone marrow
Reduced plasma concentration of all coagulation factors
Delayed fibrin monomer polymerisation - due to altered fibrinogen glycosylation
Excessive plasmin activity
Which coagulation factor is not reduced in liver disease?
Factor 8
What is the definition of a massive transfusion?
Transfusion of a volume equal to the patient’s total blood volume in less than 24 hours
OR
50% blood volume loss within 3 hours
Why can haemostatic abnormalities in a massive transfusion occur?
Due to dilutional depletion of platelets and coagulation factors
Due to DIC
Due to underlying disease, eg liver or renal drug treatment or surgery
What are the risk factors of DIC?
extensive trauma
head injury
prolonged hypotension
When does dilutional effects of haemostatis tend to occur?
when at least 7-8 litres in adults usually transfused before problems are likely
What are the dilutional effects of haemostatis?
Thrombocytopenia Coagulation factor depletion DIC - common Citrate toxicity - more common in neonates/hypothermia Hypocalcaemia
What is DIC?
Disseminated intravascular coagulation
Widespread activation of the clotting cascade
formation of blood clots in the small blood vessels
leads to ischemia
Activation of fibrinolysis
What are the management options for DIC?
Treat underlying cause i.e. antibiotics, chemo, Obstetric intervention
Supportive treatment: Maintain tissue perfusion
Co-ordinate invasive procedures
Folic acid and Vitamin K to support recovery period if illness prolonged
How are Oral Anticoagulants doses determined?
INR
What is used for the reversal of Oral Anticoagulant Treatment?
IV Vit K
What tests are used to monitor the anticoagulant effects of unfractionated heparin?
tests sensitive to the anti-thrombin and/or anti-Xa
APTT is most commonly used
What tests are used to monitor the anticoagulant effects of low molecular weight heparin?
anti-Xa assays
The APTT is not sensitive to LMWH
What is the management procedure of bleeding/overanticoagulation?
1) Stop infusion
2) Consider protamine administration - maximum 40mg
What is the difference between LMWH and UFH?
LMWH - Higher ratio of anti-Xa to anti-IIa activity
LMWH - Longer half life allowing once daily administration
LMWH - More predictable anticoagulant response: monitoring is not routinely required
