Flashcards in Acquired Bleeding Disorders Deck (25)
Name 6 acquired bleeding disorders
Vit K deficiency
Massive transfusion syndrome
How do you determine if a bleeding disorder is due to an inhibitor or a deficiency?
If APTT is prolonged, repeat with 50:50 mix patient to normal plasma. Deficiency= significant correction, inhibitor=no correction
In which aquired bleeding disorder is the TT the longest?
Why does liver disease result in clotting disorders?
Clotting factors are synthesised in the liver
Why does massive transfusion result in bleeding disorders?
Dilution of clotting factors
In which bleeding disorders is the thrombin time increased?
DIC and heparin overuse
In which bleeding disorders is the platelet concentration decreased?
What are the vitamin K dependent clotting factors?
How does vit. K usually work?
Acts as a cofactor in a modification step after the synthesis of the clotting factors- vit K reductase works to reduce vit k epoxidase back to its active form- vit k (red)
How does warfarin work?
Inhibits the recycling of vitamin K i.e. blocks the synthesis of vit k reductase
4 causes of vitamin K deficiency
Obstructive jaundice (bile salts can't reach the gut, fat and subsequently vit. k can't be absorbed)
Prolonged nutritional deficiency
Broad spectrum antibiotics
Neonates (1-7 days) 'haemorrhagic disease of the newborn
What is the cause of haemorrhagic disease of the newborn?
Vit K deficiency at birth
What is the monitoring blood test for warfarin and what is the normal range?
International normalised ratio INR (PT)
How does heparin work?
Activates antithrombin III which results in an increased rate of inactivation of thrombin and factor Xa
How does fondaparinux work?
Acts against factor Xa
What is the monitoring blood test for fondaparinux?
It does not require monitoring
How does aspirin work?
Irreversible Cox 1 and cox 2 (mainly) inhibitor which blocks the synthesis of thromboxane which is a procoagulant in primary haemostasis
Causes of bleeding disorders in liver disease
Thrombocytopenia (splenic congestion)
Low plasma concentration of all factors, apart from factor 8
Impaired vit. K absorption- reduced synthesis of vit K dependent facotrs
What is the definition of massive transfusion
Transfusion of a volume equal to the patient's total blood volume in less than 24hrs or 50% in less than 3 hrs.
Causes of bleeding in massive transfusion
Dilutional depletion of platelets and coagulation factors (5, 8 and fibrinogen)
Causes of DIC
Lab tests in DIC
D-dimer (fibrin degredation product) increased
Complications of DIC
tissue damage caused by thrombosis- necrosis and further activation of coagulation and fibrinolysis
Purpura, ecchymoses, GI bleeding
Renal function impaired due to microvascular thrombosis
Acute respiratory distress syndrome, adrenal necrosis, chock and thromboembolism
What affects warfarin metabolism in the liver
Erythromycin/antibiotics slow down metabolism of warfarin- over anti-coagulation