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Anesthesia Pharmacology II > Anticoagulants > Flashcards

Anticoagulants Flashcards

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1
Q

how does heparin work?

A

binds AT III

Enhances its activity 1000 fold

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2
Q

Which factors does AT III inhibit?

A

9-12

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3
Q

What kind of chemical compound is heparin?

A

Sulfated glycosaminoglycan

Can be either bovine or porcine derived

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4
Q

What is a unit of heparin?

A

Volume of heparin-containing solution that will prevent 1 ml of citrated sheep blood form clotting for 1 hour after the addition of 0.2 ml of 1:100 CaCl

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5
Q

Because of its large size, heparin does not cross the placenta. T/F

A

T

Pts taking anticoagulants may be changed heparin once they become pregnant

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6
Q

Heparin is well abosorbed and may be taken PO. T/F

A

F

Heparin has poor lipid solubility

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7
Q

Why isnt heparin given IM?

A

Risk of hematoma

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8
Q

Heparin is ________ protein bound.

A

highly

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9
Q

What determines the half life of heparin?

A

dose dependent

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10
Q

What is normal aPTT and ACT?

A

aPTT 30 sec

ACT: 90-120s

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11
Q

What ACT would you want to see in vascular surgery?

A

250 s

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12
Q

What are some clinical uses of heparin?

A 
Venous Thrombosis/ Pulmonary Embolism
Post MI thrombosis
Unstable angina
Post thrombolysis
Extra-corporeal circulation
DIC
Pregnancy uses
Bridge therapy with longer acting drugs
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13
Q

Define:
Thrombus
Embolus

A

Thrombus- Formation of a clot

Embolus- When a clot moves and lodges somewhere else

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14
Q

What is the dose of heparin for vascular surgery pts? CPB pts?

A

Vascular 100 units/kg

CPB 300-400 units/kg

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15
Q

Flor vascular surgery, you should ask the surgeon if they would like to redose heparin after __________ _________.

A

about 45 minutes. at vascular dose half life is about 1 hour

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16
Q

How much circulation time should you give after giving heparin and before cross clamping?

A

3 min

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17
Q

What are the contraindications for heparin?

A

Ocular surgery
Intracranial surgery
Spinal/ Epidural
Peripheral nerve blocks

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18
Q

What is mild thrombocytopenia?

A

Most common
205 days post exposure
Platelet count < 100K cells/mm3 blood
Reversible

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19
Q

What is considered severe thrombocytopenia?

A 
More than 5 days out
Platelet count < 50K cells/mm3 blood
Heparin resistance
HITT
Thrombosis is 20%.  Mortality is 40%
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20
Q

What is HITT?

How common is it?

A

Heparin-Induced Thrombocytopenia and Thrombosis
5-28% patients develop HIT
Seen as fall in platelet count after heparin exposure
Heparin therapy must be discontinued

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21
Q

What is protamine made from? What’s the mechanism for inactivating heparin?

A

made from salmon sperm

protamine is + charged, while heparin is -, so they bind together

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22
Q

What is the dose of protamine?

A

text says 1mg/100 u heparin

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23
Q

Why should protamine be given on a pump or in a minidrip setup?

A

Causes hypotension with rapid administration

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24
Q

What happens if too much protamine is given?

A

the protamine prolongs anticoagulation and becomes an anticoagulant itself

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25
what are side effects of protamine?
hypotension pulmonary hypertension allergic reaction
26
Which patients are likely to have a protamine alllergy?
NPH insulin Vasectomy/Infertility Fish allergy
27
What are two alternatives to protamine?
Platelet factor 4 (PF4) - Platelet concentrates - Heparin-binding protein - Reverses actions of heparin Heparinase-I -Heparin-degrading enzyme OR you could just wait it out
28
What is enoxaparin?
``` Lovenox--low molecular weight heparin given as subq shots DVT prophylaxis ( total hip or knee)--not given in or ```
29
What size is lovenox?
400-500 daltons
30
How often is lovenox taken?
once daily
31
Coumarin derivatives may cross the placental barrier and cause fetal abnormalities. T/F
T
32
Coumarin derivatives cause defective protein formation of which coag factors?
2,7,9,10 | Jen's mnemonic: 2+7=9 and then 10...
33
Anticoagulation with coumarin derivatives is rapid. T/F
F, because it takes time for new, defective proteins to form, these have delayed onset
34
What 2 labs should be monitored with coumarin?
PT | INR-therapeutic between 2-3
35
What are the clinical uses of coumarin derivatives?
``` Prevent venous thromboembolism Prevent systemic embolism -A-fib -Mechanical heart valves Stroke prevention ```
36
How long should coumadin be discontinued before surgery?
5 days
37
What can be given as a bridge for coumadin? how long should they be discontinued before surgery?
Heparin (last dose 4 hours preop) | LMWH (last dose 24 hours preop)
38
What do you do if a pt on coumadin comes to the OR emergently?
Vit K ( usually given enterally) FFP recombinant factor VII
39
What are the side effects of coumadin?
Hemorrhage Skin necrosis Fetal changes - CNS damge - hemorrhage
40
Can a breast feeding mother take coumadin?
yes-doesn't affect breast milk
41
What is the goal of giving thrombolytics?
REstore circulation to a previously occluded vessel
42
What is the mechanism of thrombolytics?
activate plasminogen to plasmin-the key to starting clot breakdown
43
Name 4 thrombolytics
Streptokinase Urokinase Alteplase-TPA Anistreplase
44
Which drugs are considered antithrombotic?
Hirudin Aspirin Clopidogril
45
What's another name for Hirudin? | How does it work and what are ists clinical uses?
``` Argatroban Supresses platelet function Clincally- -Prevention of DVTs in hip replacement -Alternative to heparin in HITT ```
46
Aspirin blocks production of _________
Thromboxane
47
Clopidogrel is is prodrug with slow onset. T/F
T
48
How long should clopidigrel be stopped before surgery?
7 days
49
what is doese of clopidegrel?
75mg/day
50
What are the indications for clopidogrel?
Reduce rate of stroke, MI and death after MI Peripheral artery disease Acute coronary syndrome
51
What are the platelet glycoprotein IIb/IIIa antagonists? | HOw do they work?
Abciximab, Eptifibatide, Tirofibran | Block frbrinogen form binding to receptors in the final common pathway of platelet aggregation
52
What are the uses of glycoprotein IIB/IIIa antagonists?
INterventional cardiology procedures | acute coronary syndrome
53
How do you monitor glycoprotein IIb/IIIa antagonists?
ACT and platelet count
54
Name 2 antifibrinolytics. How do they work? What is their use?
``` Lysine analogs and Aprotinin -Amicar and transexamic acid Inhibit proteolytic activity of plasmin Used for cardiopulmonary bypass -Since during CPB the fibrinolytic pathway gets upregulated ```
55
What are guidelines for surgery after balloon angioplasty?
If less than 14 days delay elective surgery | After 14 days proceed to OR on aspirin
56
What are guidelines for Bare metal stent?
If less than 30-45 (4-6 weeks) days delay elective surgery | After 30-45 days proceed to OR on aspirin
57
What are guidelines for drug eluting stent?
If less than 365 days delay elective surgery | After 365 days proceed to OR on aspirin
58
What is periop managemet of pts at high risk for cardiac events?
Continue aspirin through periop period Stop plavix at least 5days (prefer 10d) Resume plavix 24 hours post op
59
What is periop mangaement for pts at low risk for cardiac events?
Discontinue antiplatelet therapy 7-10d efore surgery | Resume antiplatelet therapy 24 hours postop
60
What is timeline for heparin surrounding neuraxial anesthesia?
Needle placement ok 1 hour before heparin D/C heparin 2-4 hours before catheter removal LMWH for bridge therapy---needle placement 24 hours after last dose
61
Sub Q heparin is a contraindication for Neuraxial anesthesthesia. T/F
F
62
HOw long is surgery delayed after a bloody tap?
24 hours
63
What should be checked on pts receiving heparin for > 4 days before neuraxial anesthesia?
Platelet count
64
What are guidelines for neuraxial anesthesia for pts with oral anticoagulants?
40% of each factor for normal coagulation INR < 1.5 associated with normal hemostasis D/C coumadin 4-5 days INR MUST be normalized Avoid other anti-clotting drugs Catherter removal with INR < 1.5
65
What should INR be before catheter is removed on a pt receiving neuraxial anesthesia on coumadin
<1.5
66
How long should plavix be D/Ced befor neuraxial anesthesia?
7 days
67
NSAIDS aside from asprin have short term effects on platelets that return to normal in ____ days with no increase in risk of spinal hematoma
3
68
HOw long should epidural be avoided when abciximab?
until platelet function has recovered-24 hours
69
Which neuraxial technique is best with direct thrombin inhibitors?
NONE
70
Which class of drugs is an absolute contraindication for neuraxial anesthesia?
thrombolytics
71
What is the pradaxa?
Direct thrombin inhibitor similar to coumadin. Doesn't require monitoring like coumadin
72
What is the drawback to pradaxa?What is therapy?
no reversal | The therapy is : time, activated charcoal, dialysis

Anesthesia Pharmacology II (11 decks)

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