Coagulation Flashcards
1
Q
tunica intima
A
- inner layer of vessel
- endothelium
2
Q
tunica media
A
- middle layer
- smooth muscle
3
Q
tunica externa
A
- outer layer
- connective tissue
4
Q
4 steps of hemostasis
A
- vascular spasm
- formation of platelet plug
- coagulation and fibrin formation
- fibrinolysis when clot is no longer needed
5
Q
Collagen
A
procoagulant
6
Q
vWF
A
- procoagulant
- fx: plt adhesion
- synthesized by vascular endothelium
- anchors PLT to vessel wall at site of vascular injury
- carries inactivated factor 8
7
Q
fibronectin
A
- procoagulant
- fx: cell adhesion
8
Q
protein C
A
- anticoagulant
- fx: degrades factor 5a & 8a
9
Q
protein S
A
- anticoagulant
- fx: cofactor for protein C
10
Q
antithrombin
A
- anticoagulant
- fx: inactivates 2a, 9a, 10a , 11a, 12a
11
Q
tissue pathway factor inhibitor
A
- anticoagulant
- fx: inhibits tissue factor
12
Q
thrombomodulin
A
- anticoagulant
- fx: regulates naturally occurring anticoagulants
13
Q
plasminogen
A
- fibrinolytic
- fx: precursor to plasmin
14
Q
tPA
A
- fibrinolytic
- fx: activates plasmin
15
Q
urokinase
A
- fibrinolytic
- fx: activates plasmin
16
Q
alpha-antiplasmin
A
- antifibrinolytic
- fx: inactivates tPA, urokinase
17
Q
plasminogen activator inhibitor
A
-antifibrinolytic
- fx: inhibits plasmin
18
Q
thromboxane A2
A
vascular smooth muscle vasoconstrictor
19
Q
ADP
A
vascular smooth muscle vasoconstrictor
20
Q
serotonin
A
vascular smooth muscle vasoconstrictor
21
Q
nitric oxide
A
vascular smooth muscle vasodilator
22
Q
prostacyclin
A
vascular smooth muscle vasodilator
23
Q
Where are platelets produced?
A
bone marrow by megakaryocytes
24
Q
normal PLT count
A
150,000 - 300,000
25
Lifespan of a PLT
8-12 days
26
PLT cleared by?
1. macrophages in reticuloendothelial system
2. spleen
27
External Membrane of PLT
Glycoproteins
- adhere to injured endothelium, collagen,
fibrinogen
- GpIb attaches activated PLT to vWF
- GpIIb-IIIa complex links PLT together to form
plug
Phospholipids
- prostaglandin synthesis
- produce thromboxane A2--> activates PLT
28
Internal component of PLT
1. Actin & myosin = PLT contraction
2. Thrombosthenin = PLT contraction
3. ADP = PLT activation & aggregation
4. Ca+
5. Fibrin stabilizing factor = crosslinks fibrin
6. Serotonin = activates nearby PLTs
7. Growth factor = repair damaged vessel wall
29
Natural PLT inhibition
In the absence of vascular injury, the endothelium inhibits PLT fx by secreting:
1. Prostaglandin I2 = inhibits vWF, TxA2 activation
2. Nitric oxide = inhibits TxA2 receptor
30
PLT receptors
1. GPIb
2. ADP
3. TxA2
4. Thrombin
5. GPIIb-IIIa
31
Hemostasis: Vascular spasm
Immediately following vascular injury, the vessel contracts to reduce blood flow to area
2 functions:
1. reduces blood loss
2. help procoagulant remain in affected area
32
Primary hemostasis: Platelet Plug
1. Adhesion
2. Activation
3. Aggregation
33
Adhesion
1. Injury exposes collagen
2. PLT adhere to collagen via GpIa/IIa & Gp VI
3. vWF released from endothelium, binds to GpIb, anchors PLTs
34
Activation
1. Collagen & thrombin activate PLT
2. PLT release ADP & TXA2 --> nearby PLT active
3. PLT contract & release fibrinogen, fibronectin, vWF, PLT factor 4, PLT growth factor
4. PLT swell, misshapen, sticky --> stick to other PLT & injury site
Activated PLT express GpIIb & GpIIIa on surface
35
Aggregation
- GpIIb/IIIa complex links activated PLT together to form PLT plug
36
3 steps required to form PLT plug
- Adhesion
- Activation
- Aggregation
37
vWF binds to the PLT during which step?
Adhesion
38
How does the injured vessel initially activate the PLT plug?
Endothelial injury exposes collagen. Exposed collagen at the site of vascular injury activates PLT
39
Clotting factor mnemonic
Foolish
People
Try
Climbing
Long
Slopes
After
Christmas
Some
People
Have
Fallen
40
Factor 1
Fibrinogen (liver)
41
Factor 2
Prothrombin (liver)
42
Factor 3
Tissue factor (vascular wall)
43
Factor 4
Calcium ions (diet)
44
Factor 5
Labile factor (liver)
45
Factor 7
Stable factor (liver)
46
Factor 8
Antihemophilic factor (liver)
47
Factor 9
Christmas factor (liver)
48
Factor 10
Stuart-Prower factor (liver)
49
Factor 11
Plasma thromboplastin antecedent (liver)
50
Factor 12
Hageman factor (liver)
51
Factor 13
Fibrin stabilizing factor (liver)
52
Coagulation cascade
- Extrinsic = 3, 7 "can be purchased for 37c"
- Intrinsic = 8, 9, 11, 12 " if you can't buy IP for $12, can buy for $11.98
- Final common = 1, 2, 5, 10, 13 "can be purchased at 5 & dime (10) for 1 or 2 dollars on 13th of month"
53
Which coagulation factors are vitamin K dependent?
II, VII, IX, X
54
Which clotting factors are a part of the extrinsic pathway?
III, VII
55
Extrinsic pathway measured by what lab?
PT, INR
56
What drug inhibits intrinsic pathway?
warfarin
57
How fast can a clot form via the extrinsic pathway?
~15 sec
58
Intrinsic pathway measured by what lab?
PTT, ACT
59
Intrinsic pathway inhibited by what drug?
heparin
60
What is the first factor to be depleted in the patient w/ vitamin K deficiency?
factor VII (also applies to liver failure & pt on coumadin)
61
4 mechanisms that counterbalance blot formation
- Vasodilation & washout of ADP & TXA2
- Antithrombin inactivating thrombin
- Tissue factor pathway inhibitor neutralizes tissue factor
- Release of protein C & S
62
2 enzymes that convert plasminogen to plasmin
- tPa
- urokinase
63
What 2 enzyme inhibitors turn off the fibrinolytic process?
- tPa inhibitor
- A2 antiplasmin
64
How are plasmin activators used therapeutically?
they help dissolve thrombi to restore blood flow
65
Fibrinolysis
66
aPTT
- Activated Partial Thromboplastin Time
- Assesses intrinsic & common pathways
- Monitors heparin
- Normal = 25-32 sec
-
67
PT
- Prothrombin time
- Monitors warfarin
- Normal = 12-14 sec
68
INR
- International Normalization Ratio
- Normal = ~1
- Target for coumadin = 2-3 x control
69
Activated clotting time
- Guides heparin dosing
- Normal = 90-120 sec
- > 400 for CPB
70
PLT count
- Monitors #, not function
- Normal = 150,000 - 300,000
71
Bleeding time
- Monitors PLT function
- Evaluates PLT plug
- Normal = 2-10 min
72
D- Dimer
- Monitors fibrinolysis
- Normal = < 500 mg/ml
73
Best predictor of bleeding during surgery
H&P
74
TEG components
75
R time
- time to begin forming clot
- normal = 6-8 min
- problem = coags
- Tx = FFP
76
K time
- Time until clot has achieved fixed strength
- Normal = 3-7 min
- Problem = fibrinogen
- Tx = cryo
77
Alpha angle
- Speed of fibrin accumulation
- Normal = 50-60 degrees
- Problem = fibrinogenn
- Tx = Cryo
78
Maximum amplitude
- Highest vertical amplitude on TEG
- Measure clot strength
- Normal = 50-60 mm
- Problem = PLT
- Tx = PLT +/- DDAVP
79
A60
- Height of vertical amplitude 60 minutes after maximum amplitude
- Normal = 5
- Problem = excess fibrinolysis
- Tx = TXA, aminocaproic acid
80
Normal
81
factor deficiency anticoagulation
82
impaired PLT number or function
83
primary fibrinolysis
84
hypercoagulation
85
DIC stage 1 (hypercoagulable)
86
DIC stage 2 (hypocoagulable)
87
Heparin inhibits which pathway?
intrinsic & final common pathway
88
Heparin MOA
- Inhibits intrinsic & final common pathways
- binds to AT3 & accelerates its anticoagulant ability
- neutralizes thrombin & activates factors 9, 10 ,11, 12
89
CPB dose for heparin
300-400 U/kg
90
therapeutic heparizination occurs when aPTT is:
1.5 - 2.5 x normal ( normal = 25-35 sec)
91
Can a pregnant patient receive IV heparin?
yes, it doesn't cross placenta
92
Protamine
- derived from salmon sperm
- positively charged protamine & negatively charged heparin create neutralization
- dose = 1 mg for every 100 U heparin
93
Protamine SE
- Hypotension (histamine); push slow
- Pulmonary HTN ( TxA2 & 5HT release)
- Allergic reaction (previous sensitization to NPH, fish allergy, vasectomy)
94
Coumadin inhibits factors:
2, 7, 9, 10, protein C & S
95
Warfarin
- Inhibits vitamin K dependent factors (2, 7, 9, 10, protein C & S)
- Highly protein bound
- Monitored w/ PT/INR
- Antidote = Vit K, FFP, recombinant VIIa, prothromin complex concentrate
96
Risk factors for vit K deficiency
- Poor dietary intake
- ABX therapy kills off GI flora & reduces Vit K synthesis
- Malabsorption d/t obstructive biliary tract dz
- Hepatocellular dz
- Neonates do not have intestinal flora that synthesizes vit K
97
Clopidogrel
- ADP receptor inhibitor
- Stop 5-7 days preop
98
Ticlopidine
- ADP receptor inhibitor
- Stop 14 days preop
99
Prasurgel
- ADP receptor inhibitor
- Stop 7-10 days preop
100
Ticagreclor
- ADP receptor inhibitor
- Stop 5-7 days preop
101
COX inhibitor MOA
- prevent PLT aggregation by blocking cyclooxygenase 1
- stop conversion of arachidonic acid to prostaglandins & ultimately thromboxane A2
102
Aspirin
- COX inhibitor
- Stop 7 days preop
103
NSAIDs
- COX inhibitor
- Stop 1-2 days preop
104
Heparin
- Unfractioned - stop 6 hrs preop
- LWWH - stop 1-2 days preop
105
Warfarin
- Vit K antagonist
- Stop 2 -4 days preop
106
Antifibrinolytics
- Stop conversion of plasminogen to plasmin
- promote clot formation
- TXA, aminocaproic acid
107
Fibrinolytics
- conversion of plasminogen to plasmin
- break down clots
- tPA, urokinase, streptokinase, reteplase, alteplase
108
tPA
- Plasminogen activator
- Stop 1 hr preop
109
vWF Dz
- Most common inherited d/o of PLT fx
- Normal PLT count, Plt dysfunction
- Increased PTT & bleeding time
- Tx:
1. **DDAVP** - stimulates release of vWF & increases factor 8 activity
2. **Cryo** (8,13, fibrinogen, vWF)
3. **FFP** (all clotting factors)
4. Purified 8-vWF
110
Hemophilia A
- X linked
- Factor 8 deficiency
- Prolonged PTT
- Tx: **factor 8 conc, FFP, cryo**
111
Hemophilia B
factor 9 deficiency
112
DIC
- Disorganized clotting & fibrinolysis
- Thrombin formation creates microvascular clots that impair tissue perfusion causing hypoxia & acidosis
- Activates anticoagulant system leading to consumption of coag factors, fibrinogen, & PLT
- S/S
1. Ecchymosis
2. Petechiae
3. Mucosal bleeding
4. Bleeding at IV site
- High risk = sepsis, OB, malignancy, preeclampsia, placental abruption, AFE
- Tx = IVFs, FFP, PLTs, Cryo, IV heparin, LMWH
113
Protein C & S deficiency results in:
- hypercoagulability
- thrombosis
114
Coagulation d/o tx w/ desmopressin
- vWB Type I > II
- Hemophilia A
115
MOA Desmopressin/DDAVP
stimulates release of vWF & increases factor 8 activity