Acquired bleeding disorders Flashcards
What are the acquired bleeding disorders?
-Vit K deficiency
-Liver disease
-Massive transfusion syndrome
-Disseminated Intravascular coagulation
Iatrogenic
-Acquired inhibitors
What is the most important factor when assessing a patient with a potential bleeding disorder?
Family/medical history
If the APTT is prolonged, how do we determine if there is a blood deficiency or inhibitor?
Mix 50:50 patient blood with normal blood
If corrected = deficiency of clotting factor
If not corrected = inhibitory substance stopping reactions working
What does liver disease do to the platelet count, PT, APTT, and CT?
- reduced platelets (portal hypertension congests spleen where 1/3 platelets are produced)
- prolong PT, APTT,
- Clotting time = normal
What does DIC do to the platelet count, PT, APTT, and CT?
Reduces platelets and prolongs all coagulation screening times
What does massive transfusion do to the platelet count, PT, APTT, and CT?
Reduced platelets (relative plasma ratio reduces with RBC transfusion)
Prolonged ATPP and TP time
Normal clotting time
What does warfarin do to platelet count, PT, APTT, and CT?
Noam platelet time
Prolonged APTT (grossly), PT (mildly) but normal clotting time
What does heparin do to platelet count, PT, APTT, and CT?
normal platelet count
Prolonged APTT and prolonged clotting time
What does circulating anticoagulant do to platelet count, PT, APTT, and CT?
Normal platelet count, CT
Might prolong PT/APTT
What are the vit K dependent clotting factors?
II (prothrombin), VII, IX, X
Where are all clotting factors produced?
Liver haptocytes (except for factor 8 - Kuppfer cells?)
What is the function of vitamin K?
Cofactor for II, VII, IX, X after they have been synthesised
Add gamma glutamyl carboxylase to end of proteins, which activates them
How does warfarin act as an anticoagulant?
Vitamin K antagonist
Blocks recycling of vit K (vitamin K reductase) - II, VII, IX, X cannot function
What factors are affected by bit K deficiency?
II, VII, IX, X
What are the causes of vitamin K deficiency?
Obstructive jaundice/liver disease
Prolonged nutritional deficiency
Borad spectrum antibiotics - vit K produced by gut flora
Neonates - 1-7 days - Vit k deficient
What causes impaired haemostasis in liver disease?
Portal hypertension - thrombocytopenia with congested spleen
Platelet dysfucntion
All clotting factors reduced except 8 (produced in Kuppfer cells)
Excessive plasmin activity
What is the definition of a massive transfusion?
Transfusion pf a volume of blood equal to total patients blood volume in less than 24 hrs or 50% of patients total blood volume in less than 3 hrs
How does massive transfusion effect haemostats?
Dilution effects of platelets and coagulation factors, mainly factors V, VIII and fibrinogen
What are other complications of massive transfusions?
Hypothermia
Citrate toxicity
DIC
What is the mechanism by which DIC inhibit haemostats?
Inappropriate activation of coagulation and fibrinolytic systems.
Consumption of clotting factors and platelets with activation of fibrinolysis
Free fibrin plugs also cause thrombosis and organ failure
What is the main causes of DIC (acute/chronic)?
Acute
-Sepsis - tissue damage/necrosis
Chronic DIC
- malignancy
