Coagulation 5 Flashcards
Heparin inhibits the:
a. extrinsic pathway
b. intrinsic pathway
c. extrinsic and final common pathways
d. intrinsic and final common pathways
d. intrinsic and final common pathways
Heparin inhibits the:
a. extrinsic pathway
b. intrinsic pathway
c. extrinsic and final common pathways
d. intrinsic and final common pathways
d. intrinsic and final common pathways
Heparin inhibits the
intrinsic and final common pathways
Heparin binds to ___________
antithrombin (& accelerates its anticoagulant ability by 1000)
The heparin-AT complex neutralizes
thrombin 2a and factors 9a, 10a, 11a, and 12a
& platelet function
Dosing of heparin for cardiac surgery is
300-400 U/kg
VTE prophylaxis of heparin is
5,000 U SC BID or TID
The unstable and acute MI dose of heparin is
5,000 U IV then infusion of 1,000 U/hr
Side effects of heparin include
hemorrhage & heparin-induced thrombocytopenia
allergic reaction
hypotension
decreased antithrombin concentrate
Heparin should not be used with
neurologic procedures
HIT
regional anesthesia
Heparin is reversed with
1 mg of protamine for every 100 units of heparin
The risk of protamine allergy is increased in patient’s who’ve
been sensitized to NHP insulin or have a fish allergy
Failed heparinization should prompt consideration of
AT deficiency
What is the volume of distribution of heparin?
small
How is heparin metabolized?
by heparinase
What are the pathways for elimination of heparin?
Degradation by macrophages & renal excretion
Can heparin be given to the parturient?
yes, it does not cross the placenta
Therapeutic heparinization occurs when
aPTT is 1.5-2.5 times normal
ACT is affected by
hypothermia
thrombocytopenia
deficiency of fibrinogen, factor 7, or factor 12
How is heparin’s anticoagulant activity stopped with protamine?
the positive charge of protamine and the negative charge of heparin create a neutralization reaction that stops heparin’s anticoagulant activity
_____________ clears the heparin-protamine complex
The reticuloendothelial system
When given alone, protamine is a
anticoagulant
Side effects of protamine include
hypotension
pulmonary hypertension
allergic reaction
Why does hypotension occur with protamine?
due to histamine release
Why does pulmonary hypertension occur with protamine?
TxA2 and serotonin release
Where is endogenous heparin produced?
liver, basophils, and mast cells
Warfarin inhibits factors:
a. 3 & 10
b. 2, 7, 9, & 10
c. 2, 7, 9, 10, and protein C
d. 2, 7, 9, 10, protein C and protein S
d. 2, 7, 9, 10, protein C, and protein S
Warfarin inhibits
vitamin K
The target PT value for a patient on warfarin therapy is
2-3 timex normal
Warfarin can be reversed with
FFP (fast) or vitamin K (slow-not good for emergent reversal)
Vitamin K is a _________ vitamin that requires the presence of __________ for absorption
fat-soluble; fat & bile
Vitamin K deficiency produces
coagulopathy
Vitamin K supplementation requires
a function liver
Vitamin K supplementation requires ___________ to restore the concentration of vitamin K dependent clotting factors in the blood.
4-8 hours
IV administration of vitamin K is associated with
life-threatening anaphylaxis
If vitamin K is given via the IV route, the rate should not exceed
1 mg/min
Warfarin is _____________________ protein bound
highly
Warfarin requires ___________- to achieve a therapeutic concentration
36-72 hours
For emergent or high-risk procedures, such as intracranial procedures, warfarin should be reversed with
FFP (1-2 units)
recombinant factor 7a
prothrombin complex concentrate
These can impair fat absorption and therefor produce vitamin K deficiency
malabsorptive disease and decreased bile production
Risk factors for vitamin K deficiency include
poor dietary intake
malabsorption due to obstructive biliary tract disease
hepatocellular disease
abx therapy kills off the GI flora and reduces bacterial synthesis of vitamin K
Neonates do not have the intestinal flora that synthesizes vitamin K
_________ is another name for exogenously administered Vitamin K
phytonadione
The dose of Vitamin K is
10-20 mg PO, IM, or IV
Where do we obtain inactive vitamin k?
diet
manufactured in the gut via bacteria
How does warfarin work?
it inhibits vitamin K epoxide reductase complex 1 (an enzyme) which indirectly inhibits production of vitamin-K dependent factors
