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Coagulation Flashcards

(110 cards)

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1
Q

4 steps of hemostasis

A
  1. vascular spasm
  2. formation of platlet plug (primary hemostasis)
  3. coagulation & Fibrin Formation (seconday hemostasis)
  4. Fibrinolysis when clot is no longer needed
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2
Q

Clotting to death is an issue when blank predomindates

A

procoagulants

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3
Q

what are the risks when procoagulatns dominate?

A

risk of stroke, MI, thrombosis elsewhere in body

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4
Q

blank and blank favor clot formation

A

procoagulants and antifibrinolytics

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5
Q

bleeding to death is an issue when blank and blank predominate

A

anticoagulants and fibrinolytics

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6
Q

name the procoagulants and their function

A

coagulation factors: coagulation
collagen: tensile strength
wVF: platelet adhesion
Fibronectin: cell adhesion

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7
Q

Name the anticoagulants and their function

A

protein C: degrade Factors 5a and 8a

protein S: cofactor for protein C

antithrombin: inactivates 2a (thrombin) 9a, 10a, 11a, 12a

tissue pathway factor inhibitor: inhibits tissue factor

thrombomodulin: regulates naturally occurring anticoagulants

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8
Q

Name the fibrinolytics and their function

A

plasminogen: precursor to plasmin (breaks down fibrin)

tPa: activates plasmin
urokinase: activates plasmin

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9
Q

Name the antifibrinolytics and their function

A

alpha 2 antiplasmin: inhibits free plasmin in the blood

plasminogen activator inhibitor: bind to tpa and urokinse to accelerate clearance

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10
Q

List the vasoactive mediators and their function

A

Vascular smooth muscle constriction:
thromboxane A2
ADP
serotonin

Vascular smooth muscle relaxation:
Nitric Oxide
Prostacyclin

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11
Q

where are platelets produced?

A

megakarocytes in bone marrow

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12
Q

normal platelet count

A

150,000 - 300,000 /mm^3

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13
Q

platelet lifespan

A

8-12 days or 1-2 weeks

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14
Q

what body organ can sequester platelets for later use?

A

spleen

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15
Q

because of platelets small size where do they end up in vasculature?

A

pushed toward the vessel wall which strategically places them close to their site of action

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16
Q

which cells make up the structural component of clots?

A

platelets

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17
Q

besides forming the structural component of blood clots, what other function to platelets perfrom?

A

deliver many substrates necessary for clot formation

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18
Q

waht two things are found on platelets membranes and what is their function?

A

glycoproteins - repelled by healthy vascular endothelium and adhere to injured endothelium , collagen, and fibrinogen

phospholipids: produce thromboxane A2 that activates platelets

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19
Q

what role do platelet GpIb receptors play in clot formation?

A

hooks activated platelets to vWF

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20
Q

what role do platelet GpIIb-IIIa receptors play in clot formation?

A

links platelets together to form a plug

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21
Q

in the absence of vascular injury endothelium inhibits platelets by?

A

secreting prostaglandin I2 and nitric oxide

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22
Q

name the platelet receptors

A

GPIb
ADP
TxA2
Thrombin
GPIIb-IIIa

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23
Q

explain the mechanism of action of the vascular spasm, the first step of hemostasis

A

SNS reflexes
myogenic response
release of vasoactive substances

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24
Q

common sources that can cause vascular spasm

A

surgery
trauma
plaque dislodgement
spontaneous microvascular injury (this occurs many times a day)

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25
vascular spasms serve two purposes:
1. decrease blood loss 2. help pro-coagulants stay at affected area to do their job
26
what are the three steps of Primary hemostasis, or platelet plug formation
1. Adhesion 2. Activation 3. Aggregation
27
what do platelets adhere to during adhesion
collagen
28
blank binds blank to the subendothelium during platelet adhesion
vWF binds GPIb receptor to the sub endothelium during adhesion
29
von willebrand disease is a disorder of...
platelet adhesion
30
which two things activate platelets
collagen and thrombin
31
activated platelets release what? what is their function?
ADP and thromboxane A2 both serve to activate nearby platelets and platelet aggregation thromboxane A2 also serves as vasoconstrictor
32
once activated how do platelets shape change?
they become swollen, irreguarly shaped, and sticky this helps them stick together and stick to site of injury
33
activated platelets express which two glycoproteins on their surface?
GpIIb and GpIIIa
34
for what kind of injury is platelet plug sufficent without activation of coagulation cascade?
micro injuries for micro injuries the coagulation cascade is not needed to stop bleeding and the platelet plug is sufficient
35
why is coagulation cascade needed in addition to platelet plug for significatn vascular injuries?
platelet plug only forms loose, fragile, temporary fix and coagulation cascade is required to form fibirin threads that strengthen the clot
36
what is the primary purpose of the coagulation cascade?
produce fibrin and form stabilized clot
37
what is the classical coagulation cascade model
intrinsic, extrinsic, and final common pathways
38
what is the cell based coagulation model?
modern hybrid understanding coagulation is initiated by extrinsic pathway with release of Tissue Factor 3 intrinsic pathway amplifies the thrombin generating effects of the extrinsic pathway
39
List each clotting factor and the mnemonic to remember them
Foolish people try climbing long slopes after Christmas some people have fallen 1. Fibrinogen 2. Prothrombin 3. Tissue Factor 4. Calcium ions 5. Labile Factor 7. Stable Factor 8. Anti-hemophilic Factor 9. Christmas Factor 10. Stuart-Power Factor 11. Plasma thromboplastin antecedent 12. hageman Factor 13. Fibrin stabilizing Factor
40
draw the clotting cascade
41
what three points go along with clotting cascade drawing?
8 and 5 are cofactors 2,7,9,10 are circled beause Vit K Dependent 3&4 are not blood proteins
42
explain the steps in the extrinsic pathway
tissue trauma liberates TF from subendothelium TF activates Factor 7 7 activates 10 in the presence of Ca++ prothrombin activator and platelet phospholipids activate factor 2 factor 5 is positive feedback mechanism to accelerate continued production of prothrombin activator
43
what is prothrombin activator?
name for all the factors that lead to thrombin activation
44
how fast does extrinsic pathway happen?
only needs 15 seconds
45
which factor has the shortest half life? how short is it? when is this important?
factor 7 4-6 hrs will be the first factor to become deficient in: liver failure Vit K Deficiency those on warfarin
46
List the steps of the intrinsic pathway
blood trauma exposure to collagen activates Factor 12 12a activates 11 (this requires HMW Kininogen) (accelerated by prekallikrein) 11a activates 9 9a & 8 activates 10 prothrombin activator and phospholipid activate thrombin (2a) (this is the same last step as in extrinsic pathway)
47
in what disease is factor 8 missing?
hemophilia A
48
which step in intrinsic pathway requires HMW Kininogen
12a activation of 11
49
prekallikrein acceleartes which step in intrinsic cascade?
12a activation of 11
50
what is the final goal of both the inrinsic and extrinsic pathways?
create prothrombin activator (prothrombinase)
51
what is prothrombinase / prothrombin activator?
10a + 5a + 4
52
explain the steps of the final common pathway
Promthrombinase / prothrombin activator coverts prothrombin (2) to thrombin (2a) thrombin changes fibrinogen to fibrinogen monomer in the presence of Ca++ Fibrin fibers are created after platelets aggregate fibrin is incorporated into platelet plug. Activated fibrin stabilizing factor (13a) facilitates cross linkage of fibrin fibers. This completes the clot
53
how long does the final blood clot (from final common pathway) stay in place?
until the underlying tissue has repaired itself
54
what factors limit the size of clot formation?
vasodilation and washout of ADP and TxA2 antithrombin - inactivates 2a, 9a,10a,11a,12a tissue factor pathway neutralizes tissue factor protein C and S inhibit factors 5a and 8a
55
when are clots broken down?
once the body has healed itself, at this point the clot is no longer needed
56
describe the process of fibrinolysis
1. plasminogen is incorported into clot as it is built, but lays dormant until activated 2. plasminogen is converted to plasmin by tPA and urokinase 3. plasmin breaks fibrin down into fibrin split products
57
how are fibrin split products measured?
d-dimer
58
where is plasminogen sythesized?
in the liver
59
where does tPA come from? is it a major or minor mechanism of plasminogen activation?
released from injured tissue over days to months and is a major mechanism
60
where does urokinase come from and is it a major or minor mechanism?
produced by kidneys and released into circulation it is a minor mechanism
61
what else can activate plasminogen to plasmin and where does it come from?
streptokinase from streptococi this is situation specific
62
what are the two off switches for fibrinolyis?
alpha 2 antiplasmin plasminogen activator inhibitor
63
what does alpha 2 antiplasmin do?
inhibits plasmin
64
what does plasminogen activator inhibitor do?
inhibits conversion of plasminogen to plasmin
65
what is the main idea of the contemporary cell based coagulation cascade?
coagulation takes place on the surface of a cell that expresses tissue factor
66
what are the three main steps of the contemporary cell based coagulation cascade?
1. Initiation 2. amplification 3. propagation
67
describe the initiation phase of the contemporary cell based coagulation cascade
started by factors 3 and 7 small amount of thrombin is created but not enough to activate fibrin
68
describe the amplification phase of the contemporary cell based coagulation cascade
platelets, factors 5 and 11 activated
69
describe the propagation phase of the contemporary cell based coagulation cascade
starts with factor 10 activation positive feedback so enough thrombin is produced to activate fibrin
70
why do thrombin levels stay low during initiation phase?
because tissue factor pathway inhibitor limits the amount of tissue factor released
71
which pathways does aPTT measure?
intrinsic and final common pathway
72
what medications does aPTT monitor?
unfractionated heparin NOT LMWH
73
normal aPTT value?
25-35 seconds remember this will be longer than PT because PT monitors extrinsic pathway which is faster than intrinsic pathway
74
how much must coagulation factors decrease by before a change in aPTT is noted?
must decrease by more than 30% before aPTT will be affected
75
which clotting pathways does PT measure?
extrinsic and final common pathways
76
PT monitors for therapeutic response to which drug?
warfarin
77
normal PT
12-14 seconds
78
how much must coagulation factors decrease before PT will be affected?
must decrease by MORE than 30% before PT will be affected
79
what is INR?
standardizes PT measurements so that PT values can be compared from lab to lab
80
what is a normal INR and what is the goal for therapeutic warfarin?
1 is normal 2-3 control is the goal for warfarin therapy
81
what is ACT used for?
to guide heparin dosing
82
normal ACT value?
90-120 seconds
83
what ACT do you need before initiating cardiac bypass?
ACT >400
84
when do you measure ACT?
before heparin 3min after giving heparin every 30min thereafter
85
which is more accurate PTT or ACT? and when?
ACT is more accurate when large doses of heparin are used, i.e cardiac bypass
86
what does a platelet count give us? what does it not tell us?
only number of platelets, not platelet function
87
normal platelet count
150,000-300,000 mm^3
88
platelet count less than x increases risk of surgical bleeding
< 50,000
88
platelet count less than x increases risk of spontaneous bleeding
20,000
88
what does bleeding time monitor? is it used often?
platelet function no, not used often clinically
89
what is a normal bleeding time?
2-10min
90
what drugs prolong bleeding time? I.e. affect platelet function
Aspirin NSAIDs
91
what does D-dimer monitor?
fibrinolysis
92
what does elevated d-dimer indicate?
that a thrombus is likely present somewhere in the body
93
what is a normal d-dimer value?
< 500mg/ml
94
differential for elevated d-dimer should include what?
DVT, PE, DIC
95
what is the definition of R/CT on TEG/ROTEM and what does it indicate? what is the normal value?
time to begin clot formation 4-8min
96
what is the definition of K/CFT on TEG/ROTEM and what is the normal time
time until clot has reachd fixed strength 1-4min
97
what does the A angle on TEG/ROTEM show what is normal?
speed of fibrin accumulation 53-72 degrees
98
what is MA/MCF on TEG/ROTEM what is normal value?
greatest vertical angle 50-70mm
99
what is LY30 / LI30 on TEG/ROTEM what is normal and what does it tell us?
% decrease in MA or MCF 0-8% shows fibrinolysis
100
normal teg
101
factor deficiency or anticoagulation
102
impaired platelet count or function
103
primary fibrinolysis
104
hypercoagulation
105
DIC stage 1 hyper-coagulable state with 2ndary fibrinolysis
106
DIC stage 2 hypo-coagulable state
107
Identify the part of the coagulation system that is assessed by each color from left to right and the associated treatment Which sections measure coagulation and which sections measure fibrinolysis?
coagulation factors : FFP fibrinogen : Cryo thrombin generation and fibrin deposition : Cryo platelets : plateletes / DDAVP plasmin : TXA / Amicar first three measure coagulation last two measure fibrinolysis
108

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