Anticoags|Procoags Flashcards by Adriana Comerford

Vessel damage = tissue factor (TF) release which binds with VIIa = conversion of X to Xa = small amount of thrombin

Initiation Phase

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Plts, V & XI activated by thrombin

Amplification Phase

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-VIII, IX and calcium on plts = activation of X while thrombin activates plts, V, VIII =VIIIa-IXa complex
The VIIIa-IXa complex switches reaction to intrinsic tenase (Xase) pathway
So increased Xa = large amount of thrombin

Propagation Phase:

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this drug binds to antithrombin causing enhanced binding with thrombin which means?

heparin and if thrombin is bound..it is not available for clotting

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uses of heparin?

prevent/treat thrombus
PE
coronary syndromes
HD
CP bypass

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onset of subcu hep vs IV?

subcu 1-2 hours, IV immediate

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what is heparin affected by?

temperature, protein binding, pt variable anticoagulation response, renal & hepatic disease

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is heparin or LMWH [lovenox] more susceptible to temp, protein binding, renal/hepatic dz?

LMWH!

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3 lab values that can be used to monitor heparin and when to choose which one?

Low dose xa
high dose (bypass) ACT 350-400
aPTT

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therapeutic range of aPTT on hep?

1.5 - 2.5 x NL (N=30-35 sec)

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what is HIT

heparin induced thrombocytopenia

plt count <100,000 or 50% drop from baseline

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MOA of HIT

heparin dependent antibodies trigger plt aggregation which causes thrombocytopenia

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Reversal of heparin?

protamine - 1 mg for each 100 units circulation heparin

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why do we overdose protamine?

protamine clearance is 20 min faster than heparin clearance (1/2 life 1 hr) so could run risk of heparin rebounding

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UFH & LMWH ↑ risk of neuraxial hematoma especially with

especially with NSAIDs, platelet inhibitors

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why is lmwh have more consistent pharmacokinetics and better bioavailability at lower doses

Less protein binding than heparin

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2 things to be cautious with when using LMWH

renal dz and its not antagonized by protamine

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Predictable onset (but delayed for 8-12 hrs) and duration, effective PO; requires lab monitoring, difficult to reverse, crosses placenta

Warfarin (Coumadin®)

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elimination half-life warfarin?

24-36 hours

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Warfarin (Coumadin®) affected by

diet, drugs, ETOH, age, liver disease

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Monitoring warfarin is Best w PT but unreliable, what did we do to fix this

INR - moderate = 2-3

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Major surgery mgmt of warfarin?

Monitor INR peri-op; D/C 1-3 days pre-op; reinstitute 1-7 days post-op; UFH bridging for high-risk clotters

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Reversal of warfarin?

Vitamin K (takes days)
PCCs for immediate reversal but availability issues FFP (transfusion risk and volume concerns)

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some examples of Newer Oral Anticoagulants (NOACs)

direct thrombin inhibitors

Dabigatran (Pradaxa®), Bivalirudin (Angiomax®, Angiox®), Argatroban (Arcova®)

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some examples of Newer Oral Anticoagulants (NOACs) | direct Xa inhibitors

Rivaroxaban (Xarelto®), Apixaban (Eliquis®), Fondaparinux (Arixtra®)

Advantages Newer Oral Anticoagulants (NOACs)

Rapid onset, therapeutic range within hours, no need for routine lab monitoring

disadvantages Newer Oral Anticoagulants (NOACs)

Needs adjusted dose with renal disease, no antagonists, unable to monitor w simple lab assays, ↑ inter-patient variability

common cause of death after first 24 hours post-trauma

meds to use for VTE Prophylaxis

Heparin LMWH (Enoxaparin, Dalteparin) Xa inhibitors (Fondaparinux, Rivaroxaban) Thrombin inhibitors (Dabigatran, Argatroban)

Low risk Peri-op management with NOACs

D/C 24 hrs pre-op, resume 24 hrs post-op

Peri-op management with NOACs Mod-high risk

D/C 5 days pre-op, resume when risk of bleeding drops

Peri-op management with NOACs Elective procedures

Bridging probably not required; consider patient-specific risk/benefits

Peri-op management with NOACs ER procedures

Delay as long as possible; do not prophylax w recombinant VIIa (Novo 7) or PCCs

when should you Consider recombinant VIIa or PCCs

Life-threatening hemorrhage

Monitoring NOACs

aPTT and TT

IRREVERSIBLY inhibits cyclooxygenase = thromboxane A2 (7-10 days)

aspirin

when can you resume aspirin therapy?

24 hrs postop without bleeding

Thienopyridines examples

Clopidogrel (Plavix®); Prasugrel (Effient®); Ticagrelor (Brilinta®)

Thienopyridines MOA?

Binds to P2Y12 receptor = inhibits platelet activation and aggregation

Dual antiplatelet therapy ex

Thienopyridine (Plavix) + ASA

Dipyridamole (Persantine®) MOA?

↑ cyclic AMP  ↓ plt function

Dextran MOA

Binds to platelets = inhibited function

Platelet glycoprotein IIb/IIIa antagonists MOA

abciximab (ReoPro®); tirofiban (Aggrastat®); eptifibatide (Integrilin®) Bind or inhibit fibrinogen receptor = ↓ plt aggregation

Peri-op recommendations | Thienopyridines

D/C 7 days pre-op, avoid neuraxials until drug effects cleared

: Risks/benefits must be individualized, especially with elective procedures

ALL antiplatelets

Thrombolytics examples?

Streptokinase, urokinase, tissue plasminogen activator (tPA) (Alteplase®)

Thrombolytics MOA

Activates plasminogen to plasmin = clot breakdown

Use: Emergent treatment of PE, CVA, acute MI without PCI availability

Thrombolytics

Risks thrombolytics?

Intracranial hemorrhage; angioedema (especially with ACE inhibitor)

Treatment of too much thrombolytics?

Cryoprecipitate and/or platelets

Block conversion of plasminogen to plasmin = inhibited clot lysis [does not induce clotting, just prevents breakdown]

Tranexamic acid (TXA) & aminocaproic acid (Amicar®):

TXA Studies show

↓ blood loss, ↓ blood products; no ↑ risk of unwanted thrombi

TXA must be administered at

<3 hours post-injury

TXA reduces risk of death due to bleeding, regardless of the cause.”

CRASH-3 and WOMAN studies

Most efficacious dose TXA for non trauma patients?

15 mg/kg

Contraindications TXA?

Hypersensitivity to antifibrinolytics Acquired color vision deficit Caution with renal impairment Caution with thrombus history

reactions include: Anaphylaxis, pulmonary vasoconstriction with RV failure, hypotension

Protamine

Adverse reactions increased with protamine in patients who

NPH insulin, vasectomy, prior protamine, drug allergies

Analog of vasopressin, stimulates endothelial von Willebrand factor

Desmopressin (DDAVP)

Desmopressin (DDAVP) uses?

Mild hemophilia A, von Willebrand’s dz, cardiac surgery(?)

Binding site for IIb/IIIa receptors on platelets

fibrinogen

normal fibrinogen level and with pregnancy?

200-400 mg/dL; during pregnancy: >400 mg/dL

Elevated PT and PTT d/t ↓ fibrinogen should be treated with

cryoprecipitate or fibrinogen concentrates (can be refractory to FFP)

For hemophilia; off-label use for life-threatening hemorrhage VIIa + tissue factor = thrombin and amplified hemostasis Off-label use in CV surgery

Recombinant Factor VIIa (NovoSeven®)

Kcentra®, Octaplex®, FEIBA VH®, Profilnine®, Bebulin VH®

Prothrombin Complex Concentrates (PCCs)

Primary treatment for hemorrhage with ↑ INR when urgent reversal needed

Prothrombin Complex Concentrates (PCCs)

Compared to FFP: PCCs =

faster reversal, less volume, no cross-matching

Anticoags|Procoags Flashcards

(67 cards)