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Board Study > Coagulation > Flashcards

Coagulation Flashcards

1
Q

Mechanisms that limit size of the clot

A
  • vasodilation: washing out ADP and TxA2
  • anti-thrombin: inactivating thrombin
  • tissue factor pathway inhibitor: neutralizing TF
  • Protein C & S: inhibit factors III, V, VIII
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2
Q

Protein C & S inhibit which factors?

A

III, V, VIII

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3
Q

Mechanisms that breakdown the clot (fibrinolysis)

A
  • plasminogen

- plasmin

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4
Q

Plasminogen

A
  • proenzyme
  • synthesized in the liver
  • incorporated into clot dormant until activated
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5
Q

Plasmin

A
  • proteolytic enzyme

- degrades fibrin into fibrin degradation products

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6
Q

Plasmin activation involves what substances?

A
  • tPA

- Urokinase

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7
Q

When is tPA released?

A
  • released by injured tissue over a period of days (major mechanism)
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8
Q

Where is Urokinase produced?

A
  • produced by the kidneys and released into circulation (minor mechanism)
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9
Q

What are the mechanisms that turn off Fibrinolysis

A
  • tPA inhibitor

- alpha-2 antiplasmin

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10
Q

What is the action of tPA?

A

inhibits conversion of plasminogen to plasmin

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11
Q

What is the action of alpha-2 antiplasmin?

A

inhibits the action of plasmin on fibrin

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12
Q

Contemporary Cell-Based coagulation cascade consists of what 3 phases?

A
  • initiation: TF/VIIa rxn activates factor X (common pathway) - makes small amt of thrombin (IIa)
  • amplification: activates plts, V, and XI
  • propagation: produces enough thrombin to activate fibrin
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13
Q

Activated Partial Thromboplastin Time (aPTT)

A
  • assesses intrinsic and common pathways
  • 25-32 sec
  • measures time it takes to form a clot using phospholipid, calcium, & an activator
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14
Q

International Normalized Ration (PT/INR)

A
  • assesses extrinsic and common pathways
  • 12-14
  • measures time it takes to form clot w/ TF and Ca+
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15
Q

INR

A
  • Normal: 1

- target for warfarin: 2-3 x control

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16
Q

Plt Count

A
  • monitors # of plts (not how well they fxn)
  • 150,000 - 300,000
  • < 50,000 inc. surgical bleed risk
  • < 20,000 inc. spontaneous bleed risk
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17
Q

Bleeding Time

A
  • monitors plt fxn
  • 2-10 min
  • ASA and NSAIDs prolong bleeding time
  • not commonly used in practice
18
Q

Activated Clotting Time (ACT)

A
  • guides heparin dosing
  • 90-120
  • ACT >400 sec before CPB
  • measured before heparin, 3 min. after its given, & every 30 min thereater
19
Q

TEG - R Time

A
  • time to begin forming clot
  • problem: coagulation factors
  • tx: FFP
20
Q

TEG - K Time

A
  • time until clot has achieved fixed strength
  • problem: fibrinogen
  • tx: cryo
21
Q

TEG - Alpha Angle

A
  • speed of fibrin
  • problem: fibrinogen
  • tx: cryo
22
Q

TEG - Max Amplitude (MA)

A
  • highest vertical amplitude on TEG
  • measures clot strength
  • problem: plts
    t- tx: plts +/- DDAVP
23
Q

Amplitude at min. after max aimplitude (A60)

A
  • height of vertical amplitude 60 min. after max amplitude
  • problem: excess fibrinolysis
  • tx: Tranexamic, aminocaproic acid
24
Q

Endogenous heparin is produced by…

A
  • basophils
  • mast cells
  • liver
25
Q

Exogenous heparin is produced by…

A
  • bovine and porcine GI mucosa
26
Q

Heparin MOA

A
  • inhibits intrinsic and final common pathways
  • Antithrombin III: natural anticoagulant in the plasma
  • Heparin binds to antithrombin and accelerates it 1000 fold
  • AT complex neutralizes thrombin and factors X, XII, XI, & IX
  • inhibits plt fxn
  • failed heparin should consider AT deficiency
27
Q

Heparin Pharmacokinetics

A
  • metabolized by heparinase
  • elimination: degradation by macrophages & renal excretion
  • doesn’t cross the placenta & is safe in pregnancy
28
Q

aPTT therapeutic normal

A
  • 1.5-2.5x normal (25-35 sec)
29
Q

ACT is affected by…

A
  • hypothermia
  • thrombocytopenia
  • deficiency of fibrinogen, factor VII, or factor XII
30
Q

Heparin side effects

A
  • hemorrhage
  • Heparin Induced Thrombocytopenia (HIT)
  • allergic rxn
  • Hypotension
  • dec. ATIII Concentration
31
Q

Heparin contraindications

A
  • neurological procedures
  • Heparin induced thrombocytopenia
  • regional anesthesia
32
Q

Protamine

A
  • derived from salmon sperm

- 1mg per every 100 u

33
Q

Another name for vitamin k

A

Phytonadione

34
Q

IV administration of vitamin k is associated with?

A
  • life threatening anaphylaxis

- if given IV, rate should not exceed 1 mg/min

35
Q

Cryoprecipitate contains which factors?

A

VIII, XIII, fibrinogen, & vWF

36
Q

Which coagulopathies prolong PTT but no PT?

A

Hemophilia A

Hemophilia B

37
Q

What lab values are increased and decreased in DIC?

A

PT/PTT: inc
D-dimer: inc
Plts: dec
fibrinogen: dec

38
Q

3 conditions associated with high risk of DIC

A
  • sepsis (highest risk = gram - bacilli)
  • OB complications (highest risk = preeclampsia, placental abruption, amniotic fluid embolism)
  • malignancy (highest risk = adenocarcinoma, leukemia, lymphoma)
39
Q

What are the supportive treatments for DIC?

A
  • Hypovolemia: tx w/ IV fluids
  • coagulopathy: replace consumed blood components w/ FFP, plts, cryoprecipitate
  • severe microvascular thrombosis: IV heparin or LMWH
40
Q

Antithrombin deficiency

A
  • antithrombin captures factors XII, XI, X, and IX which ultimately leads to thrombin (IIa) inhibition
  • heparin works by inc anticoagulant effect of AT by 1000 fold
  • pts w/ AT deficiency are unresponsive to Heparin
  • repeated heparin administration can consume the body’s supply of AT & produce an acquired form of AT deficiency
  • tx: AT concentrate and FFP
41
Q

Triggers of sickle cell anemia

A
  • pain
  • hypothermia
  • hypoxemia
  • acidosis
  • dehydration

Board Study (29 decks)

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