Clinical Aspects of Coagulation - Nikcovich Flashcards
What is Hemostasis?
Dynamic Interaction between vascular endothelium, platelets, procoagulant factors, and anticoagulant factors
What is a normal platelet count?
150-400K
What happens if the platelet count is
Increased risk of mucocutaneous bleeding and CNS hemorrhage
What is more important than the actual number of platelets?
Platelet surface area
What is the most common reason for impaired platelet function?
Aspirin
What is INR used for?
Prothrombin Time used to measure warfarin efficacy
What is aPTT used for?
Measure heparin efficacy of unfractionated heparin
What is a Chromogenic Xa assay used for?
Measure heparin levels; useful in the presence of lupus anti-coag or anti-phospholipid antibody
What is PFA-100 used for?
Platelet Function Assay that measures platelet response to ADP, collagen, epinephrine
What is Bleeding Time used for?
Measure Platelet Function (WORST TEST)
How long does aspirin’s effect last?
10 days, irreversible –> Treatment: Platelet Transfusion
What is the mechanism of warfarin?
Interferes with vitamin K dependent secondary glycosylation of factors II, VII, IX, X
How do you reverse warfarin?
Time
Vitamin K
Fresh Frozen Plasma
What are the characteristics of Unfractionated Heparin (UFH)?
Unpredictable Absorption
IV or SQ
Dosage based on body weight
Daily aPTT
What are the characteristics of LMWH?
Reliable absorption
SQ
Expensive
No need to monitor
When is Clopidogrel used?
Cardiac Stents
Strokes
Bleeding
TTP
When is tPA used?
Direct Fibrinolysis
Stroke
PE
MI
When is Vitamin K used?
Reverses Warfarin
What is the treatment for von Willebrand’s Disease?
DDAVP to increase vWF production by vascular endothelium
What does Fresh Frozen Plasma contain?
All coagulant factors in normal levels
Used to reverse warfarin, replace factors due to liver disease, or DIC
What does Cryoprecipitant contain?
Fibrinogen, vWF, Factor VIII, Factor XIII, Fibronectin
What is the best way to initiate anti-coagulation?
UFH or LMWH plus warfarin for 4-5 days then warfarin monotherapy to fully affect prothrombin (Factor II)
What is a High INR (via low factor VII) a surrogate marker for?
Depleted Protein C
A 52 y.o. male with atrial fibrillation who is managed with metoprolol, digoxin, and warfarin develops epistaxis and an INR of 10. How will you treat him?
Low dose Vitamin K
2 mg PO for 1 day
What can interfere with INR measurement leading to false readings and what else needs to be monitored while on warfarin?
Antiphospholipid Antibody
Factor II Level