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Anesthesia Pharmacology II > Anticoagulants > Flashcards

Anticoagulants Flashcards

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
Q

what are side effects of protamine?

A

hypotension
pulmonary hypertension
allergic reaction

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26
Q

Which patients are likely to have a protamine alllergy?

A

NPH insulin
Vasectomy/Infertility
Fish allergy

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27
Q

What are two alternatives to protamine?

A

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

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28
Q

What is enoxaparin?

A 
Lovenox--low molecular weight heparin given as subq shots
DVT prophylaxis ( total hip or knee)--not given in or
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29
Q

What size is lovenox?

A

400-500 daltons

30
Q

How often is lovenox taken?

A

once daily

31
Q

Coumarin derivatives may cross the placental barrier and cause fetal abnormalities. T/F

A

T

32
Q

Coumarin derivatives cause defective protein formation of which coag factors?

A

2,7,9,10

Jen’s mnemonic: 2+7=9 and then 10…

33
Q

Anticoagulation with coumarin derivatives is rapid. T/F

A

F, because it takes time for new, defective proteins to form, these have delayed onset

34
Q

What 2 labs should be monitored with coumarin?

A

PT

INR-therapeutic between 2-3

35
Q

What are the clinical uses of coumarin derivatives?

A 
Prevent venous thromboembolism
Prevent systemic embolism
-A-fib
-Mechanical heart valves
Stroke prevention
36
Q

How long should coumadin be discontinued before surgery?

A

5 days

37
Q

What can be given as a bridge for coumadin? how long should they be discontinued before
surgery?

A

Heparin (last dose 4 hours preop)

LMWH (last dose 24 hours preop)

38
Q

What do you do if a pt on coumadin comes to the OR emergently?

A

Vit K ( usually given enterally)
FFP
recombinant factor VII

39
Q

What are the side effects of coumadin?

A

Hemorrhage

Skin necrosis

Fetal changes

  • CNS damge
  • hemorrhage
40
Q

Can a breast feeding mother take coumadin?

A

yes-doesn’t affect breast milk

41
Q

What is the goal of giving thrombolytics?

A

REstore circulation to a previously occluded vessel

42
Q

What is the mechanism of thrombolytics?

A

activate plasminogen to plasmin-the key to starting clot breakdown

43
Q

Name 4 thrombolytics

A

Streptokinase
Urokinase
Alteplase-TPA
Anistreplase

44
Q

Which drugs are considered antithrombotic?

A

Hirudin
Aspirin
Clopidogril

45
Q

What’s another name for Hirudin?

How does it work and what are ists clinical uses?

A 
Argatroban
Supresses platelet function
Clincally-
-Prevention of DVTs in hip replacement
-Alternative to heparin in HITT
46
Q

Aspirin blocks production of _________

A

Thromboxane

47
Q

Clopidogrel is is prodrug with slow onset. T/F

A

T

48
Q

How long should clopidigrel be stopped before surgery?

A

7 days

49
Q

what is doese of clopidegrel?

A

75mg/day

50
Q

What are the indications for clopidogrel?

A

Reduce rate of stroke, MI and death after MI
Peripheral artery disease
Acute coronary syndrome

51
Q

What are the platelet glycoprotein IIb/IIIa antagonists?

HOw do they work?

A

Abciximab, Eptifibatide, Tirofibran

Block frbrinogen form binding to receptors in the final common pathway of platelet aggregation

52
Q

What are the uses of glycoprotein IIB/IIIa antagonists?

A

INterventional cardiology procedures

acute coronary syndrome

53
Q

How do you monitor glycoprotein IIb/IIIa antagonists?

A

ACT and platelet count

54
Q

Name 2 antifibrinolytics. How do they work? What is their use?

A 
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
Q

What are guidelines for surgery after balloon angioplasty?

A

If less than 14 days delay elective surgery

After 14 days proceed to OR on aspirin

56
Q

What are guidelines for Bare metal stent?

A

If less than 30-45 (4-6 weeks) days delay elective surgery

After 30-45 days proceed to OR on aspirin

57
Q

What are guidelines for drug eluting stent?

A

If less than 365 days delay elective surgery

After 365 days proceed to OR on aspirin

58
Q

What is periop managemet of pts at high risk for cardiac events?

A

Continue aspirin through periop period
Stop plavix at least 5days (prefer 10d)
Resume plavix 24 hours post op

59
Q

What is periop mangaement for pts at low risk for cardiac events?

A

Discontinue antiplatelet therapy 7-10d efore surgery

Resume antiplatelet therapy 24 hours postop

60
Q

What is timeline for heparin surrounding neuraxial anesthesia?

A

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
Q

Sub Q heparin is a contraindication for Neuraxial anesthesthesia. T/F

A

F

62
Q

HOw long is surgery delayed after a bloody tap?

A

24 hours

63
Q

What should be checked on pts receiving heparin for > 4 days before neuraxial anesthesia?

A

Platelet count

64
Q

What are guidelines for neuraxial anesthesia for pts with oral anticoagulants?

A

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
Q

What should INR be before catheter is removed on a pt receiving neuraxial anesthesia on coumadin

A

<1.5

66
Q

How long should plavix be D/Ced befor neuraxial anesthesia?

A

7 days

67
Q

NSAIDS aside from asprin have short term effects on platelets that return to normal in ____ days with no increase in risk of spinal hematoma

A

3

68
Q

HOw long should epidural be avoided when abciximab?

A

until platelet function has recovered-24 hours

69
Q

Which neuraxial technique is best with direct thrombin inhibitors?

A

NONE

70
Q

Which class of drugs is an absolute contraindication for neuraxial anesthesia?

A

thrombolytics

71
Q

What is the pradaxa?

A

Direct thrombin inhibitor similar to coumadin. Doesn’t require monitoring like coumadin

72
Q

What is the drawback to pradaxa?What is therapy?

A

no reversal

The therapy is : time, activated charcoal, dialysis

Anesthesia Pharmacology II (11 decks)

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