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Eq ACVS Phase 1 > Ch.4 Hemostasis, Surgical Bleeding, Transfusions > Flashcards

Ch.4 Hemostasis, Surgical Bleeding, Transfusions Flashcards

1
Q

Absorption time of CoSeal (polyethylene glycol hydrogel)

A

30 days

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2
Q

To what extent does CoSeal (polyethylene glycol hydrogel) swell

A

Up to 4 times its volume

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3
Q

How does polyethylene glycol hydrogel (CoSeal) act

A

Polymerizes to form hydrogel acting directly as a barrier to blood flow.

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4
Q

Advantages of fibrin sealants

A

1- Do not require patient to have adequate platelets or coag factors
2- Biodegradable
3 - Have not been associated with tissue inflammation or FB rxn

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5
Q

How do fibrin sealants work

A

Replicate last stage of coagulation

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6
Q

Tisseel contains what

A

Thrombin and fibrinogen

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7
Q

Flowseal is an example of

A

A thrombin product

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8
Q

Disadvantages of bone wax

A

1- Non-absorbable
2 - Inhibits bacterial clearance
3 - Inhibits bone healing
4 - Allergic rxns
5 - Granulomatous rxns
6 - Embolization

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9
Q

Biologic hemostatic effect of bone wax?

A

None - mechanical

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10
Q

Advantages of polysaccharide hemostatic agents (TraumaDex, Arista)

A

Do not inhibit wound healing

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11
Q

What polysaccharide is used in hemostatic dressings such as HemCon

A

Chitosan

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12
Q

Absorption time for TraumaDex, Arista (polysaccharide hemostatic agents)

A

24-48hrs

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13
Q

Mechanism of hemostasis of polysaccharide hemostatic agents

A

Have a porous surface which allows absorption of blood - concentrating platelets, coag factors and reduces time for coag.

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14
Q

TraumaDex and Arista are examples of?

A

Polysaccharide hemostatic agents

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15
Q

Absorption time of microfibrillar collagen hemostatic agents

A

Should be removed from surgical site before closure of wound

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16
Q

Disadvantages of microfibrillar collagen hemostatic agents
(Avtene, Instat)

A

1-Allergic reactions - related to bovine origin
2-Interfere with bacterial clearance and wound healing

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17
Q

On which patients are microfibrillar collagen hemostatic agents (Avtene, Instat) less effective?

A

Patients with thrombocytopenia.

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18
Q

How do microfibrillar collagen hemostatic agents (Atvene, Instat) act?

A

1-Bind tightly to the bleeding surface - mechanical blockage.
2-Platelets adhere to the collagen and are activated the resultaning platelet degranulation and aggregation leads to hemostasis.

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19
Q

Absorption time of microfibrillar collagen hemostatic agents

A

8-10 weeks

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20
Q

Absorption time of surgicel (oxidized regenerated cellulose)

A

7-14 days however residue may persist for several months to years.

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21
Q

Disadvantages of using surgicel (oxidized regenerated cellulose)

A

1-Can’t be soaked in thrombin - the biologic agents will be inactivated in the low pH
2-Low pH may lead to tissue inflammation and delayed wound healing.

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22
Q

Advantage of Surgicel (Oxidized regenerated cellulose) over gelatin sponge?

A

Low ph confers antibacterial properties so can be used in contaminated areas.

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23
Q

How does oxidized regenerated cellulose (Surgical) elicit its hemostatic effects?

A

1-Swelling from blood absorption,
2-Activates coagulation on the collagen surface,
3-Caustic hemostatic agent due to low ph

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24
Q

Absorption time of gelatin sponge

A

4-6 weeks

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25
Q

Contraindication of gelatin sponges

A

Not to be used in contaminated wounds - can potentiate infection

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26
Q

How does a purified gelatin sponge exert its hemostatic effect?

A

Swelling as it is soaked with blood.
Can be soaked in thrombin to help promote coagulation directly.

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27
Q

Proposed activity of Yunnan baiyao

A

Activates platelets and enhances expression of surface glycoproteins on platelets.

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28
Q

Haemostatic dose of formalin

A

10-100ml of 10% formalin in 1L isotonic saline

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29
Q

Dose of Tranexamic acid

A

5-25mg/kg

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30
Q

How are conjugated estrogens believed to contribute to hemostasis

A

Enhance platelet activity and decrease antithrombin activity

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30
Q

How are conjugated estrogens believed to contribute to hemostasis

A

Enhance platelet activity and decrease antithrombin activity

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31
Q

Dose of Aminocaproic acid

A

10-40mg/kg IV q6 diluted in 1L Saline administered slowly
or
3.5mg/kg/min for 15mins then 0.25mg/kg/min at CRI

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32
Q

How does aminocaproic acid work?

A

Lysine derivative - inhibits fibrinolysis by
1 - binding plasminogen activators and
2 - enhancing antiplasmin activity.

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33
Q

Half-life of transfused RBC of fresh crossmatched allogenic blood?

A

20 days

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34
Q

Life-span of transfused RBC of autologous blood stored for 28 days?

A

30 days

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35
Q

What % blood loss do we estimate for a horse in shock?

A

30%

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36
Q

Formula for acute blood loss volume

A

BW(Kg) x 0.08 x 0.30

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37
Q

Formula for blood transfusion

A

BW(Kg) x 0.08 x <(Desired PCV - Actual PCV)/Donor PCV>

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38
Q

What can hypocalcemia be a sign of regarding blood transfusion?

A

Citrate toxicity

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39
Q

How to treat signs of anaphylaxis in horses receiving transfusion?

A

Epinephrine 0.01 to 0.02 ml/kg IV of 1:1000 solution (0.1mg/ml),
Mild rxn tx w NSAID or antihistamine

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40
Q

If no reaction is seen in the first 20 mins of WB transfusion the rate can be increased to?

A

5ml/kg/hr for normovolemic and up to 20-40ml/kg/hr in hypovolemic horses

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41
Q

What is the rate of adverse reactions to WB transfusion?

A

16% with 2% (1/44) having a fatal reaction

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42
Q

At what rate should blood be transfused?

A

0.3ml/kg over the first 10-20mins

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43
Q

How many ml/kg body weight of plasma is advisable for treating a coagulopathy?

A

4-5ml/kgBw

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44
Q

What % of blood lost into a body cavity is auto-transfused back into circulation?

A

75% in 24-72 hours

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45
Q

What % of blood lost should be replaced y transfusion?

A

25-50%

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46
Q

For how long can USDA licensed equine plasma products be stored?

A

1 year

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47
Q

How many litres of plasmapheresis can be performed on a donor?

A

4-11L every 30 days

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48
Q

When transfusing blood from the dam to an NI foal how should the blood be prepared?

A

Wash RBC

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49
Q

At what temp should blood be stored?

A

4*C

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50
Q

For how long is blood that has been stored in saline-adenine-glucose-mannitol suitable for transfusion?

A

35 days

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51
Q

What is the % RBC survival of stored blood at 28 days?

A

73%

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52
Q

For how long can whole blood be stored in citrate-phosphate-dextrose-adenine (CPDA)-1 bags?

A

3 weeks

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53
Q

What ratio of 3.2% sodium citrate is used as an anticoagulant in blood collected for immediate transfusion

A

1:9 anti-cog : blood

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54
Q

Cons of using glass bottles to collect blood?

A

Inactivates platelets and damages RBCs

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55
Q

At what % blood collection from a donor is volume replacement with crystalloid fluids recommended?

A

15%

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56
Q

What % of its’ total blood volume can a healthy horse donate?

A

20% every 30 days

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57
Q

Transfused RBC from cross-matched incompatible blood have a half life of?

A

4.7 days

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58
Q

Transfused RBC from fresh autologous blood have a half life of?

59
Q

Transfused RBC from a cross-matched compatible donor have a half life of?

60
Q

If the minor cross-match is incompatible but the major is can the transfusion be performed?

A

Yes after washing the donor RBCs

61
Q

Rapid agglutination method tests what?

A

Detects RBC antigens Ca and Aa

62
Q

What does the minor cross-match involve?

A

Mixing recip RBC with the donor serum

63
Q

What does the major cross-match involve?

A

Mixing the donor’s washed RBCs with the recip’s serum

64
Q

What can be added to the reaction mixture to detect hemolytic reactions?

A

Rabbit complement

65
Q

How long after an initial blood transfusion of unmatched blood is it safe to perform a second one?

A

Within 2-3 days

66
Q

How soon after a transfusion can horses develop alloantibodies?

67
Q

The ideal blood donor should be..

A

Gelding,
young,
healthy
>500kg,
vaccinated inc rhino, tet, etc
Lack Aa Qq alloantigens

68
Q

How many recognized equine blood groups?

69
Q

Action of plasmin in fibrinolysis?

A

Degrades fibrin and fibrinogen into soluble F degradation products,

inactivates FVa and FVIIIa and
degrades prekallikrein and HMWK

70
Q

Plasminogen activators such as what convert plasminogen to plasmin.

A

tPA (tissue plasminogen activator) and
uPA (urokinase plasminogen activator) &
Kallikrenin

71
Q

Where is plasminogen produced?

A

Kidney and liver

72
Q

What is the principle component of the fibrinolytic system?

A

Plasminogen an inactive zymogen

73
Q

What is the primary mechanism of clot dissolution?

A

Activation of the fibrinolytic system

74
Q

Function of Thrombin in amplification process?

A

Cleaved vWF/FVIII allowing vWF to stimulate platelet adhesion.

75
Q

What constitutes the amplification of coagulation?

A

Adherence, activation and aggregation of platelets along with the accumulation of activated co-factors

76
Q

What does the TF-FVIIa complex activate?

A

FX and FIX

77
Q

What is the primary initiator of coagulation?

A

Tissue Factor TF

78
Q

What are the 3 phases of physiologic hemostasis?

A

Initiation, amplification and propagation

79
Q

How does FXIIIa stabilize the clot?

A

Cross-linking strands of fibrin monomer in the presence of Ca2+

80
Q

In the final step of clot formation FIIa converts what?

A

Fibrinogen to fibrin

81
Q

FX in the presence of of activated FVa, Ca2+ and a platelet phospholipid converts what?

A

prothrombin(FII) to thrombin (IIa)

82
Q

The extrinsic pathway starts with the activation of?

A

FVII by TF present in fibroblasts or other TF bearing cells

83
Q

The common coag pathway is marked by the activation of?

84
Q

What procoagulant does FIX bind to in the presence of Ca2+?

85
Q

FXIa activates FIX in the presence of?

86
Q

What contact proteins interact with FXII to accelerate its activation?

A

High molecular weight Kininogen (HMWK) and Prekallikrein.

87
Q

The intrinsic pathway is initiated by?

A

Activation of Factor XII and subsequently XI on the surface of activated platelets

88
Q

How does prostacyclin prevent unwanted expansion of platelet aggregates?

A

Decreases ADP release

89
Q

Platelet activation Is promoted by?

A

Thrombin,
collagen,
ADP,
Thromboxane A2

90
Q

How is platelet adhesion mediated?

A

P-selectin and platelet receptor GPIb𝜶 which attaches to vWF.

91
Q

What is responsible for degradation of unwanted cellular debris after complete activation of fibrin formation?

A

Acid hydrolayses in platelet lysosomes

92
Q

What stores the majority of platelet proteins needed for the initiation of coagulation?

A

𝜶 Granules, Dense granules and lysosomes

93
Q

What is the strongest stimulant for release of contents from dense granules?

94
Q

Function of Ca2+ in hemostasis?

A

Cofactor in platelet-phospholipid interactions

95
Q

What do dense granules store?

A

Ca2+,
ADP,
Adenosine triphosphate and
serotonin.

96
Q

What proteins do 𝜶 granules contain?

A

1- Fibrinogen,
2- Factor V,
3- Factor VIII,
4- Fibronectin,
5- vWF,
6- Platelet derived growth factor,
7- Platelet factor 4.

97
Q

What are the largest and most prevalent storage granules in platelets?

A

Alpha 𝜶

98
Q

What does local vasoconstriction, platelet activation, adhesion and aggregation lead to the formation of?

A

A temporary platelet plug

99
Q

From what are von Willebrand factor released?

A

Weibel-Palade bodies

100
Q

How do endothelial cells react to vessel injury?

A

Express TF and
downregulate expression of thrombomodulin, becoming procoagulant.
Release von Willebrand factor promoting platelet adhesion.

101
Q

Immediate response of the blood vessel to injury is?

A

Vasoconstriction

102
Q

What does AT (Antithrombin) inactivate?

A

Thrombin and coag factors 7a, 9a,10a and 11a

103
Q

How do enzymes on the endothelial surface prevent clotting?

A

Prevent platelet agg and adhesion by degrading ADP Adenosine Diphosphate

104
Q

What’s the action of of prostacyclin and nitric oxide (NO) on clotting?

A

Inhibit platelet aggregation. NO also inhibits platelet adhesion and causes vasodilation causing low turbulence flow.

105
Q

What is responsible for antiplatelet properties of the endothelium?

A

Prostacyclin and nitric oxide

106
Q

What are the fragments produced as FDPs

A

Fragments X, Y, D and E

107
Q

Plasmin degradation of the cross-linked fibrin results in

A

D Dimer degradation product

108
Q

The principle inhibitors of coagulation are

A

AT
Heparin
Protein C
Protein S
TFPI

109
Q

What is responsible for 70-80% of thrombin inhibition in the coagulation system

110
Q

Where is heparin produced

A

Mast cells in lungs, liver, kidney, heart and GI

111
Q

How does Heparin affect AT

A

Conformation change increasing AT activity 1000 fold

112
Q

What do D-Dimer result from

A

Degradation of fibrin

113
Q

What do FDPs indicate

A

Degredation of either fibrin or fibrinogen

114
Q

How to measure D-Dimers

A

Latex agglutination
Latex emnhanced turbidimetric immunoassay

115
Q

What does increased D-Dimers indicate

A

Increased fibrinolysis
or
Inability to clear the products from circulation

116
Q

How to test for DIC

A

Platelet count - thrombocytopenia
Clotting time - Prolonged PT/APTT
Fibrinogen conc = Decreased
D-dimer conc = incresed
FDP = increased

117
Q

Protein C activity in inflammation

118
Q

How to treat DIC

A

Treat primary disease
Fresh frozen plasma - will provide AT
Polymixin B
NSAIDs
Heparin

119
Q

What forms of heparin are used in DIC treatment, why?

A

Use the Low molecular-weight heparin - 4.5kDa
- Greater inhibition of FXa
- Longer half life than UFH
- Dose dependent clearance

Unfractioned heparin (15kDA) associated with
- Prolonged APTT and decreased PCV

120
Q

Heparin regimen for LMWH vs UFH Heparin in DIC

A

LMWH 4.5 kDa
Dalteparin: 50-100 units/kg SQ q24
Enoxaparin: 40-80 units/kg (0.35mg/kg) SQ q24

UFH 15kDa
Heparin Ca2+: 150IU/kg SQ once
then
125IU/kg SQ q12 for 3 days
then
100IU/kg SQ q12

(Use 40-80iu/kg if sodium heparin)

121
Q

What are the principle inhibitors of coagulation

A

AT
Heparin
Protein C
Protein S
TFPI

122
Q

Deficiencies in what can result in prolonged PT

A

FV
FVII
FX
Prothrombin
Fibrinogen

Extrinsic and common pathways

123
Q

How is prothrombin time measured

A

Plasma mixed with thromboplastin and Ca2+

Time to clot measured

Increase by 20% = abnormal

124
Q

TBT will be prolonged in what conditions

A

Thrombocytopenia
Thrombocytopathia
Lack of WVF

125
Q

Tests of primary hemostasis

A

Platelet count <100,000/ul
TBT
PFA-100

126
Q

What pathway/s does Activated Partial Thromboplastin Time measure (factors)

A

Intrinsic and common

5, 7, 9 , 10, 11 prothrombin, fibrinogen

127
Q

How is an activated partial thromboplastin time test performed

A

Activating agent
plasma
glass tube
phospholipid emulsion
Ca2+

128
Q

How is the activated clotting time test performed and what does it measure

A

Time for whole blood to clot after contact with diatomaceous earth

Stimulating intrinsic and common pathways

Blood collected in tube containing diatomaceous earth and is incubated at 37*C

ACT prolonged with deficincies in 7 and 9, prothrombin and fibrinogen

Rapid patient side test

129
Q

How is AT measured

A

Chromogenic assay

130
Q

How is protein c measured

A

Chromogenic assay

131
Q

A PCV below what usually requires a blood transfusion

132
Q

Blood loss in surgery greater than what usually requires a blood transfusion

133
Q

What oxygen extraction ratio indicates need for blood transfusion

134
Q

What PCV is an indication for pRBC transfusion

135
Q

What cases might benefit from pRBC transfusion

A

Normovolemic anaemia
Isoerythrolysis NI
Erythropoietic failure
Chronic blood loss

136
Q

Plasma frozen >8 hours after collection has decreased what

A

Considered frozen not fresh frozen
Reduced F8 and 5

137
Q

FFP should be started at what rate

138
Q

What can be added to detection mixtures to detect hemolytic rxns

A

Rabbit compliment

139
Q

If the minor crossmatch is incompatible but major is compatible

A

Ok to do transfusion but with washed donor cells

140
Q

Why should glass not be used to collect

A

Inactivates platelets
Hemolysis

141
Q

What anticoagulant should be used to collect blood which will be used immediately

A

3.2% sodium citrate 1:9 anticoag:blood

142
Q

RBC stored in saline-adenine-glucose-mannitol solution can be transfused up to how many days after collection

143
Q

How often can plasmapherisis be performed in a donor

A

4-11L every 30 days

144
Q

What % of blood lost should be replaced by transfion

145
Q

Blood should be delivered at what rate

A

0.3ml/kg over 10-20mins

Eq ACVS Phase 1 (72 decks)

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