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OMS Residency > Hematology > Flashcards

Hematology Flashcards

1
Q

Virchows Triad

A

Virchow’s triad

Vessel injury

Stasis (worse with hypovolemia)

Abnormal coagulation

  • Congenital- anti-thrombin-3-deficiency, protein C/S deficiency, dysfibrinogenemia, plasminogen diseases
  • Acquired- lupus anticoagulant, nephrotic syndrome, paroxysmal nocturnal hemoglobinuria, BCP/estrogen use, polycythemia vera, sepsis
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2
Q

Steps of primary hemostasis

A

Formation of platelet plug: 1. Adhesion of platelets to damaged vascular wall (requires VIII:vWF) 2. Activation of platelets (requires thrombin (IIa) 3. Aggregation of platelets (requires ADP/TXA2) 4. Production of fibrin (requires extrinsic, intrinsic and final common pathway factors)

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3
Q

Steps of secondary hemostasis

A

Production of fibrin, coagulation 1. Initiation of thrombin generation (though TF on fibroblasts-extrinsic) 2. Amplification of thrombin generation 3. Propagation of thrombin generation 4. Fibrin formation

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4
Q

Extrinsic pathway

A

37 cents–Damage outside the vessel triggers release of thromboplastin (III), the primary initiator of coagulation. TP activates VII. VII+Ca(IV) on surface of platelet—X is activated.

Vit K dependent

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5
Q

Intrinsic Pathway

A

Intrinsic path: $12—$11.98—Trauma to the blood itself or exposure of the blood to collagen activates IX. IX/VIII:C/Ca++ on platelet surface activates X.

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6
Q

Final common pathway of coagulation cascade

A

Final Common Path: 5(V) & dime(X) for 1 or 2 dollars on the 13th of the month. X, V, & Ca on platelet surface convert prothrombin (II) to thrombin (IIa). IIa converts fibrinogen (I) to fibrin(Ia)—Ia + XIII, fibrin cross-linking occurs.

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7
Q

Coagulation Cascade

A

Extrinsic path: 37 cents–Damage outside the vessel triggers release of thromboplastin (III), the primary initiator of coagulation. TP activates VII. VII+Ca(IV) on surface of platelet—X is activated.

Intrinsic path: $12—$11.98—Trauma to the blood itself or exposure of the blood to collagen activates IX. IX/VIII:C/Ca++ on platelet surface activates X.

Final Common Path: 5(V) & dime(X) for 1 or 2 dollars on the 13th of the month. X, V, & Ca on platelet surface convert prothrombin (II) to thrombin (IIa). IIa converts fibrinogen (I) to fibrin(Ia)—Ia + XIII, fibrin cross-linking occurs.

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10
Q

What are DOACs?

A

Direct-acting oral anticoagulants (DOACs), dabigatran, rivaroxaban, apixaban and edoxaban are not required to have monitoring but are sensitive to changes in renal function and are associated with poorer adherence.

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11
Q

Coagulation half lives and initiation of Warfarin therapy, which factor is reduced first?

A

Early reduction VII 🡪 X 🡪 IX 🡪 II

Anticoagulant effects occur in ~2 days vs a minimum of 4-6 days for an initial antithrombotic effect (peak @5-7days)

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14
Q

Protein C

A

Protein C: autoprothrombin IIA and blood coagulation factor XIV, is a zymogen

Protein C has shortest half life of vit K dependent depend proteins

When on Warfarin- pt loses protein C much more quickly than the procoagulation effects of VII, II, IX, and X🡪 Warfarin necrosis

Prevented by bridging with Heparin

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15
Q

Protein C and S

A

Endothelial cell protein C receptor bind complex🡪Thrombin-Thrombomodulin complex activates Protein C🡪C+S (free protein S on endothelial or platelet phospholipids surfaces) degrade factors Va and VIIIa 🡪prev conversion of fibrinogen to fibrin

When Thrombin bound to TM, it loses its procoag fxn

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18
Q

4 classes of anticoagulants

A
  • Vitamin K antagonists (coumarin anticoagulants)
    • Warfarin
  • Low molecular weight heparins (LMWH)-
    • enoxaparin (Lovenox)
    • dalteparin (Fragmin)
    • heparin
  • Direct thrombin inhibitors
    • bivalirudin (Angiomax) – powder for injection
    • argatroban (Acova) - injectio
    • dabigatran (Pradaxa) – oral capsule
    • antithrombin III (Thrombate III) – powder for injection
  • Factor Xa Inhibitors
    • apixaban (Eliquis) – oral tablets
    • fondaparinux (Arixtra) - injection
    • rivaroxaban (Xarelto) – oral tablets
    • edoxaban (Savaysa) – oral coated tablets
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19
Q

Difference between Heparin and LMWH?

A

Both work w/ antithrombin to inactivate factor Xa, Unfractionated-heterogenous mixture of polysaccharide chains, inactivates Xa and IIa(thrombin) equaly

-5000U every 8-12hrs subQ

LMWH -fractionated natural heparin created by depolymerization, inactivates IIa to a lesser degree

-superior bioavailability and longer half life–> given once a day

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20
Q

Warfarin

A
  • vit K dependent, many food and drug interactions
  • slow acting
  • monitor INR, PT time, INR 2-3= effective dose
  • inhibits vitK reductase–> DEC in II, VII, IX, X, also protein C and S
    • can take 5 days so need fast acting ar same time
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21
Q

What is fondaparinux (Arixtra) - injection?

A

factor Xa inhibitor, no effect on Thrombin

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22
Q

What reversal agents are available for DOAC?

A

Andexxa (Andexanet alfa) FDA approved for only Apixaban (Eliquis), Rivaroxaban (Xarelto) (factor Xa inhib)

Idarucizumab- for dabigatran (Pradaxa-direct thrombin inhib)

4F-PCC- prothrombin complex concentration

American College of Cardiology

https://www.acc.org/tools-and-practice-support/mobile-resources/features/manageanticoag

23
Q

What is Tisseal?

A

Fibrin sealant, effective in heparinized patients

fibrinogen and thrombin which, upon mixing, mimics a physiological clot

aprotinin in TISSEEL increases resistance of the fibrin sealant clot to degradation in a fibrinolytic environment

-aprotinin-bovine pancreatic trypsin inhibitor (BPTI). Since it demonstrates the capacity to slow fibrinolysis

24
Q

vWF Types

A

Quantitative Type 1 and 3

Qualitative Type 2, 2A, 2B, 2M, 2N

25
Q

CBC

A
  1. RBC=(4.14-5.75 m/uL)
  2. Hgb=Males=12-18 g/ml; females= 12-16 g/ml.
  3. Hct % total bld vol made of RBC via centrifuge; M=40-54%; F=34-51%
  4. Mean Corpuscular Vol=79.7-97.6 fL; less than 80=microcytic anemia
  5. Mean Corpuscular Hgb= Hgb in RBC, 26.5-34.2 pg
  6. Mean Corpuscular Hgb Concentration: 32.9-35.5 g/dL, LO=iron DEF
  7. RDW- variation of RBC size= 12.6-15.2%
  8. WBC= 3.2-10.8 k/uL
  9. Platelet count=150,000 - 350,000/μL
26
Q

Floseal

A

human thrombin and pre-filled sodium chloride syringe

gelatin granules and human thrombin to provide fast (2 min median time to hemostasis)

27
Q

Gelfoam

A

purified pork Skin Gelatin USP Granules and Water for Injection, USP

-absorbed completely in 4-6 weeks

28
Q

Oxtmetazoline (Afrin)

A

vasoconstrictor

29
Q

Cryoprecipitate

A

1 unit= 10-20mL–> inc of 50mg/dL

Contains:

  • Fibrinogen
  • Factors VIII and XIII
  • vWF
30
Q

vWF

A

Synthesized in endothelial cells and megakaryocytes

necessary for adherence of PLTs to
exposed endothelium. vWF is a carrier
protein to F VIII:c and bound to it This
complex is part of the complete factor
VIII. Part of the intrinsic pathway:
includes factors 12, 11, 9, 5, 10, 2, 1.

31
Q

vWF Disease tratment for bleeding

A

Autosomal Dominant

TX for bleeding: Desmopressin: 0.3mcg/kg 1-2 hr
prior to surgery.
Peaks: 30 min
Duration: 6-8 hrs.
Stimulates the release of vWF from the
endothelial cells increasing plasma
concentration of vWF. Inhances
fibrinolysis by causing the release of
tissue plasminogen activator. May need
to give ε-aminocaproic acid (plasmin
activator inhibitor) with the desmopressin
to help prevent plasmin from degrading
fibrinogen and fibrin.

Desmopressin causes fluid retention

If vWF 2b- NO DDAVP, will cause thrombocytopenia

34
Q

When to transfuse?

A

hemoglobin (Hgb) is <7 to 8 g/dL(approximately equivalent to a hematocrit ≤21 to 24 percent) in most cardiac and noncardiac surgical patients

  • and symptomatic

RBC: 1unit=350mL–> INC 1g/dL–>3% Hct

35
Q

Prothrombin Plasma Concentrates versus Fresh Frozen Plasma

A

PPC indicated for fast reversal of supratherapeutic INR w/in 10min-dose of 25–50 units/kg

One dose of PCC equals 8 to 16 units of FFP

Advantages of PCC vs. FFP:10

  • More effective and rapid correction of INR
  • Greater increase in clotting factors
  • Can be infused faster than FFP and with less volume
  • Fewer complications secondary to fluid overload
  • Shorter preparation time since PCC does not need to be thawed as FFP does
  • Does not require blood-type matching

PCC contraindic in HIT

36
Q

Types of PCC 4 vs 3 factor

A

Kcentra, 4 factor= 2, 7, 9, 10 in inactive forms

Bebulin and Profilnine, 3 factor= NO factor 7

also contains heparin to prevent activation of factors and also protein C and S

OMS Residency (10 decks)

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