Anticoagulation and NOACs Flashcards
PT (INR) measures Extrinsic pathway (FVII and then combined pathway X + V -> II). Causes of prolonged PT?
Factor VII deficiency Warfarin Oral Xa inhibitors LAC Mild factor X, V or II def
aPTT measures intrinsic pathway (Factors XII, XI, IX and VIII and then combined X+V and II). Causes of prolonged aPTT?
Factors XII, XI, IX and VIII def
vWD
LAC
Mild X, V or II def
What is the best predictor of perioperative bleeding?
The bleeding history
How does Heparin affect the coag assay?
Prolong aPPT and TT
What test confirms the presence of Heparin?
Reptilase time
Activates prothrombin, not inhibited by heparin
What prolongs reptilase time?
Abnormal or reduced fibrinogen
Hypoalbuminaemia
Raised FDPs
What causes a prolonged PT and APTT?
Vit K def
Warfarin anticog
Liver failure
Combined V and VIII def
What causes a long PT, APTT, TT and normal or abnormal fibrinogen?
Heparin in large amounts
Liver disease
Finronogen def or disorder
Excess dabigatran and anticoagulation
What causes a long PT, APTT, Normal TT and Normal or abnormal Fibrinogen and low platelet count?
Massive transfusion
Liver disease
What causes a long PT, APTT, TT, low fibrinogen and low platelet count?
DIC
Acute liver disease
Antithrombin deficiency. What, associations?
AD
Prevalence of symptomatic disease 0.01%
Antithrombin inhibits XIIa, Xia, IXa and Xa
Acquired casues are DIC, cirrhosis, nephrotic syndrome and L- asparaginase therapy
Associated with VTE from puberty in 55%
Recurrence of 60%
Very high risk of VTE in pregnancy = 50%
prophylactic anti-coagulation and antithrombin concentrates at delivery
Protein C and S def.
What, prevalence, causes, associations?
AD
Prevalence of symptomatic disease is 0.1% or less
Acquired causes are liver disease, warfarin therapy, OCP and preg
Associations:
VTE from puberty, less risk than antithrombin. Spontaneous and associated with surgery, trauma, pregnancy etc.
Warfarin induced skin necrosis
Role of activated protein C?
Protein C inactivates Factor V and FVIII with protein S as a cofactor
What inherited clotting disorder is associated with venous, not arterial thrombosis?
Activated protein C resistance
- Mutation Factor V Leiden found
Moderate risk for venous thrombosis
Synergictic with OCP, preg, Sx
Elevated Factor VIII.
Cause
Main risk association
Elevtaed levels are related to ABO blood group - Group O have lower FVIII
Inherited in some
FVIII levels may rise with infection, inflammation etc
Rise with age, esp post menopause
Elevated FVIII >150% (1.5 IU/L) is associated with a 4.8 fold risk of VTE!!!
Greater than activated protein C resistance (Factor V Leiden) etc
Pregnancy associated VTE. Highest risk periods?
Highest risk post partum, 5 x higher
1st trimester higher risk than others.
Left LL more common = 85%