Clinical Aspects of Coagulation Flashcards
What does fresh frozen plasma (FFP) have?
Have everything in Cryoprecipitate
- All coagulant factors in normal levels
- May reverse warfarin effect or replace factors missing due to liver disease or DIC
What is Cryoprecipitant?
- 1U equal to cold-induced precipitation of 10U FFP
- Provides fibrinogen, vWF, factor VIII, factor XIII, fibronectin
What is the best way to initiate anti-coagulation?
- UFH plus warfarin x 4-5 days, then warfarin mono therapy
- LMWH plus warfarin x 4-5 days, then warfarin mono therapy
What does a patient have to be on both heparin and warfarin for 4-5 days?
Requires 4-5 days of warfarin to fully affect prothrombin (factor II)
What happens if a shorter induction course of warfarin is used?
20 mg daily for 1 day and the INR is therapeutic
- Is this OK?
- –Absolutely contraindicated
What factors are required for hemostasis?
- Platelets
- Procoagulant factors (clotting cascade)
- Anti-coagulant factors (Protein C, Protein S, anti-thrombin III, tPA)
- Intact vasculature
What is hemostasis?
Dynamic interaction between vascular endothelium, platelets, procoagulant factors and anticoagulant factors
What is normal platelet count?
150-400K
What happens if the platelet count is 25K?
Probably nothing
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 are is more important
What is the most common reason for impaired platelet function?
ASA (aspirin)
What happens with NSAIDs?
Usually nothing. NSAIDs have reversible platelet inhibition.
What is PT/INR?
Prothrombin Time
INR = International Normalized Ratio
(Measured PT/Control PT)^ISI = INR
-The assay used to measure WARFARIN efficacy
-Target INR 2.0-3.5, depending on clinical circumstance
What is aPTT?
- Activated partial thromboplastin time
- The assay used to measure HEPARIN efficacy
- -Unfractionated heparin
- -NOT low-molecular weight heparin
- -Also used to measure effects of argatroban and leparudin
- Therapeutic range 60-80 seconds
What is the Chromogenic Xa assay?
- A way to measure HEPARIN levels
- Can use a variant of this assay to measure warfarin efficacy if INR is unreliable
- Useful with the presence of a lupus anti-coagulant or anti-phospholipid antibody
What is PFA-100?
- A useful way to measure platelet function.
- Measures platelet response to ADP, collagen, epinephrine
- Completely automated
- Does not reveal etiology of platelet function defect
What is bleeding time test?
- Designed to measure platelet function
- Laboratroy technician nicks forearm with razor and then touches the cut intermittently with filter paper
- Keep doing this until the bleeding stops (normal
How does Aspirin work?
- Irreversible acetylation of platelets
- Aspirin effect lasts for up to 10 days
- How do you reverse aspirin? TIME & Platelet transfusion
What are NSAIDS?
- Ibuprofen, naproxen sodium, ketorolac, sulindac, indomethacin
- REVERSIBLE effect on platelet function
- Effects reversed within 6-8 hours
What is Warfarin?
- Most common anticoagulant
- Interferes with VitaK dependent secondary glycosylation of factors II, VII, IX, X
- Dosed according to INR
- Target INR 2-3 for DVT/PE
- Target INR 2.5-3.5 for mechanical heart valve
- How to reverse warfarin? VitaK, Time, Fresh frozen plasma
What should you know about Heparin?
Unfractionated Heparin (UFH) -UFH with unpredictable absorption -May be administered IV or SQ -Dosage based on body weight -Need to follow (often daily) aPTT LMWH (enoxaparin) -Extremely reliable absorption -SQ administration -No need to monitor levels -Expensive ($70-$100/day)
How does tPA act?
Direct fibrinolysis
-Used with MI, Stroke, PE
How does Vitamin K act?
- Reverses Warfarin
- May be helpful with coagulopathy of liver disease
