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Tobias Sec I-III Sample Questions > 7.Bleeding and Hemostasis > Flashcards

7.Bleeding and Hemostasis Flashcards

1
Q

Approximately how many platelets are produced each day?

a. 10^6
b. 10^9
c. 10^11
d. 10^12

A

C 10^11

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2
Q

What is the average length of circulation of a platelet in dogs?

a. 3-5 days
b. 4-6 days
c. 6-8 days
d. 7-9 days

A

C. 6-8 d

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3
Q

What is the average length of circulation of a platelet in cats?

a. 3-5 days
b. 4-6 days
c. 6-8 days
d. 7-9 days

A

still C 6-8 days ;)

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4
Q

Pick the true statement

a. Following endothelial damage, platelets adhere to subendothelial collagen via platelet-glycoprotein V or to vWF
b. Thromboxane A2 is synthesized from platelets from arachidonic acid via COX-2
c. Thromboxane recruits and activates additional platelets during primary hemostasis
d. Glycoprotein IIbIIIa is important for platelet to bind to other platelets

A

C is correct

Platlet Glycoprotein VI R: subendothelial collagen AND glycoprotein Ib R to collagen bound vWF
Cox 1 --> TXA2
Glycoprotein IIbIIIa (AKA platelet integrin alphaIIbBeta3) binds fibrinogen which then binds other platelets (final common pathway for all agonists)
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5
Q

Which of the following is true regarding buccal mucosal bleeding time?
a.BMBT is the time from incision to the time of clot formation
b.BMBT reflects in vivo secondary hemostasis
c.BMBT is prolonged with thrombocytopenia, thrombopathia, and
vasculopathy
d.BMBT is not influenced by hematocrit or blood viscosity

A

C is correct

BMBT, incision to the time of cessation of bleeding, (primary)
influenced by hematocrit, blood viscosity, skin thickness, skin temperature, age, sex, and lag interoperator and introperator variability

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6
Q

Which is true regarding PT and aPTT?

a. Prolonged PT indicated defects in the intrinsic and/or common pathways
b. PT is not sensitive for vitamin K deficiency due to a prolonged half’life of factor VII
c. With a deficiency in a single factor, prolongation of PT or aPTT (factor
depending) can be seen with 40-50% of the factor present
d. In canines, point-of-care coagulometers sensitivity and specificity for aPTT and PT are 100% and 83% (aPTT) and 86% and 96% (PT)

A

D

aPTT–> intrinsic
(factor VII has a short half-life and therefore PT is very sensitive)
Single factor must be decreased to <25-30% of normal to prolong

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7
Q

Which of the following is FALSE regarding ACT?

a. It assesses intrinsic and common pathways
b. It is the time to first clot formation
c. Normal ACT is <110 seconds for the dog and <75 seconds for the cat
d. Testing in performed on citrate tube

A

D

False, tube with diatomaceous earth

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8
Q

Which aspect of clotting is the first to become critically reduced during hemodilution?

a. Platelets
b. Factor VIII
c. VWF
d. Fibrinogen

A

D fibrinogen

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9
Q

What does the hypofibrinogenemia lead to?

A

decreases thrombin formation as well as fibrin polymerization, thus decreasing the speed, strength, and stability of clot
formation

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10
Q

At what level of fibrinogen will a clot not form?

A

a.Below 50 mg/dL

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11
Q

Which aspect of clotting is affected by hypothermia?

a. Platelets
b. Factor VIII
c. VWF
d. Fibrinogen

A

A. platelets

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12
Q

What is the effect of acidemia on clotting?

A
  1. Acidemia increases fibrinogen degradation and impairs coagulation protein activity
  2. fXa-Va complex activity is decreased by 50% at pH 7.2, and by 70% at pH 7.0.242
  3. the coagulopathy is not reversed with correction of acidemia via buffer
    administration
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13
Q

True or false: In humans, new-onset thrombocytopenia is an independent predictor of intensive care mortality, but the​ severity is NOT correlated to survival.

A

FALSE- severity is inversely related to survival

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14
Q

Which of the following statements is true?
a.The threshold of platelet count is reliably correlated with the amount of bleeding.
b.Secondary hemostasis defects are usually
characterized by echymoses and spontaneous bleeding from mucosal surfaces.
c.Petechiae are more typical of thrombocytopenia than of thrombopathia
d.Technical causes are rare of hemorrhage and do not occur in conjunction with coagulapthies.

A

C

(FALSE- it is not)
(NOPE- Primary hemostats)
(​Secondary hemostasis usually characterized by hematomas or bleedings into cavities, muscles, joints)
Technical causes are common, and can happen with any problem

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15
Q

At what point is there a risk of hemorrhage?

a. PT and APTT prolongations that exceed 1.5 times control values
b. Platelets < 70,000/uL ​
c. All Dobermans
d. Hypertension above 180mmHg

A

A

below 50,000 will suffer operative bleeding

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16
Q

Which of the following is true?

a. Cryoprecipitate contains the more stable factors II, VII, IX, and X
b. FFP contains fVIII, vWF, fibrinogen and fibronectin
c. Cryosupernatent can be used as an alternative to FFP for vitamin K deficiency
d. Desmopressin only work by enhancing release of vWF

A

C

FFP: II,VII, IX, X
Cryoprecipitate: fVIII, vWF, fibrinogen and fibronectin
Desmopressin = synthetic vasopressin analogue via V2 receptors–> release of subendothelial vWF, ALSO factor VIII and plasminogen from endothelium

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17
Q

what is the most common congenital bleeding disorder in dogs?

a. ​ ​Hemophillia A
b. ​ ​Hemophillia B
c. ​ ​vWD type 2
d. ​ ​vWD type 1

A

D

Type I identified in > 50 breedspresence of ALL multimers, but decreased concentrations

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18
Q

Which statement is correct?

a. ​ ​Type 1 vWD reduction in high molecular weight multimers
b. ​ ​Type 2 vWD the presence of all multimers with reduction in low molecular weight multimers
c. ​ ​Type 3 vWD near complete loss of all high molecular weight multimers
d. ​ ​German short hairs and wire-hairs are common breeds to get type 2 vWD?

A

D

Type 2 disproportionate loss HIGH molecular weight multimers
type 3 quantitate deficiency with almost complete absence of vWF

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19
Q

​Which is correct?
a.​ ​Hemophilia A is a deficiency with f9
b.​ ​Hemophilia B is a deficiency with f8
c.​ ​Hemophilias are recessive sex linked traits manifested in males
D. Devon Rex cats commonly get hemophilia A

A

C

A: fVIII
B: fIX
HemoA/B causes prolongation of aPTT
Devon Rex rare combined deficient of vitaminK-dependent coag f described
fXIII most common f def in cats-asymptomatic

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20
Q

What condition is NOT associated with thromboembolism?

a. Neoplasia
b. Immune-mediated hemolytic anemia
c. Diabetes mellitus
d. Pneumonia

A

D pneumonia

others include PLN, necrotizing pancreatitis, hyperadrenocorticism, corticosteroid therapy, infective endocarditis and dirofilariasis, atherosclerosis, sepsis

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21
Q

What does an increased amplitude in a TEG correspond to?

a. Platelet hyperaggregability
b. Enzymatic hyperactivity
c. Platelet dysfunction
d. Platelet hypoaggregability

A

A hyper-

hypercoagulability: increased G value, R and K values may be decreased and/or MA and alpha values increased
decreased R indicates enzymatic hyperactivity

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22
Q 
What is the only laboratory marker proven to help in the diagnosis of pulmonary 
thromboembolism? 
a.       TEG 
b.       D-dimers 
c.       FDP 
d.       Fibrinogen assay
A

B. D dimers

sensitive test,
questionable if indicator of hypercoagulability or a predictor of thrombosis

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23
Q

Which of the following is true regarding monitoring for antithrombotic agents?
a. Unfractionated heparin is monitored using PT and the goal is to achieve 1.5-2.5x
baseline
b. Low-molecular weight heparin is monitored using PTT
c.Warfarin is monitored via PT or international normalization ratio for a goal
of 1.25-1.5x and 2.0-3.0x baseline respectively

A

C

Unfractionated: aPTT of 1.5-2x baseline
Low MW heparin: anti-factor Xa assay)

24
Q

True or false: Heparin therapy should overlap warfarin therapy for at least two days

A

(true,
because for the first 1-2 days warfarin only affects those factors with short half-lives -
factor VII and protein C, and therefore has a higher risk for thromboembolism)

25
Q

Which of the following is FALSE regarding aspirin?
a. It inactivates COX-1 by causing a defect in platelets and subsequently
suppressing the synthesis of TxA2
b. Ultralow dose aspirin (0.5mg/kg q12-24hr) adequately inhibits platelet function in
dogs
c. 81mg/cat is shown to have fewer adverse events compared to 5mg/kg
d. There is not an increase in GI lesions in dogs with ultralow-dose aspirin and
prednisone

A

C
(false, opposite - 5mg/kg is better clinically in cats with ATE)

Up to 2/3 of dogs are not aspirin responders

26
Q

Which of the following is FASLE regarding Clopidogrel?
a. Platelet inhibition reaches steady state at 5-7 days after onset of treatment
b. Platelet inhibition is noted within 12-24 hours
c. It is reserved for patients that fail aspirin therapy or have a risk of vascular event
of >20% per year
d. It is a prodrug requiring hepatic metabolism to achieve antiplatelet activity

A

B
(false, by 2 days)

platelet defect persists for the life of the platelet (like aspirin) receptor blockade prevent ADP-induced activation of alphaIIbB3 integrin, fibrinogen binding, and sustained aggregation)

27
Q
  1. What are mortality rates for dogs and cats with DIC?
    a. D 30-40%, C 52%w
    b. D 20-25%, C 68%
    c. D 50-70%, C 93%
    d. D 80-100%, C 82%
A

c.D 50-70%, C 93%

28
Q

What are the most common causes of DIC in dogs?

A

a.Sepsis and SIRS

29
Q

Which tumor has the highest incidence of DIC?

a. Hemangiosarcoma
b. Melanoma
c. Mammary gland adenocarcinoma
d. Pulmonary adenocarcinoma

A

C

a. Hemangiosarcoma - 46.7%
c. Mammary gland adenocarcinoma - 50%
d. Pulmonary adenocarcinoma - 28.5%

30
Q

What are the main causes of DIC in cats? Which is the most?

a. neoplasia
b. pancreatitis
c. sepsis
d. infectious diseases

A

a. neoplasia (40%) - (Among cats with neoplasia, most had lymphoma or
carcinoma)
b. pancreatitis (26%)
c. sepsis (19%)
d. infectious diseases (13%).

31
Q

what percentage of cats have platelet aggregation?

A

up to 71%

32
Q

What are the 3 steps in cell based model coagulation?

A

Initiation –> amplification –> propagation

33
Q

What are main features of… Initiation phase?

A

TF on the surface of TF-bearing cells -> generates small amounts of IIA

34
Q

What are main features of… Amplification phase?

A

IIA amplifies the initial signal by activating PLT and cofactors (Va and VIIIa) on PLT surface

35
Q

What are main features of… Propagation phase?

A

Large-scale IIa generation occurs on the surface of the activated PLT
IIA nec. To produces large quantities of fibrin which is needed to stabilize the thrombus

36
Q

True/ False?
A Platelets do express tissue factor; coagulation can proceed when extravascular tissue factor is brought into close proximity with platelets and coagulation factors.
B The normal endothelium controls platelet reactivity through three known inhibitors: prostacyclin (PGI2), ectoadenosine diphosphatase (ecto-ADPase), and nitric oxide

A

FALSE
Platelets do NOT express tissue factor; coagulation can proceed ONLY when extravascular tissue factor is brought into close proximity with platelets and coagulation factors.

37
Q

True/false? Fibrinolysis is controlled predominantly by plasminogen activator inhibitor-1, α2-antiplasmin, and thrombin activatable fibrinolysis inhibitor.

A

true

38
Q

True/false? Three natural anticoagulant pathways are described: antithrombin, activated protein C, and tissue factor pathway inhibitor.

A

true

39
Q

True/false?The normal endothelium controls platelet reactivity through three known inhibitors: prostacyclin (PGI2), ectoadenosine diphosphatase (ecto-ADPase), and nitric oxide

A

true

40
Q

Which of the following is true?
A Pseudothrombocytopenia is uncommon, only occurring in 29% of cats
B Platelet count can be estimated by multiplying PLT/hpf x 15000, even in areas of clumping
C Psudothrombocytopenia refers to falsely low counts due to platelet clumping or large platelets

A

A 91% cats
B only in monolayer, no clumping
C TRUE

41
Q

True about BMBT?
A It is the duration of hemorrhage from the infliction of injury to only microscopic vessels
B Normal for dogs is <3.5 minutes
C Normal for cats is 34 to 105 seconds
D It is not influenced by HCT, blood viscosity, skin thickness, temp, age, sex, etc…
E There is potential for up to 3 minutes of interoperature and intraoperator variability and device related variability

A 
A TRUE
B <3 min
C sedated cats
D it IS
D up to 2 minutes
42
Q

Which is true?
A Prolongation of the PT or aPTT generally does not occur until the factor is decreased to less than 10% to 20% of normal concentrations.
B Because of the short half-life of factor VIII, the PT is very sensitive to vitamin K deficiency or antagonism
C Activated clotting time (ACT) is performed by collecting whole blood into a prewarmed (37° C) citrate tube
D Fibrin split products can inhibit coagulation and induce platelet dysfunction

A

A 25-30%
B VII, the PT is sensitive
C diatomaceous earth
D TRUE

43
Q

What is a D-dimer? What does it indicate?

A

D-Dimer is a neo-epitope produced when soluble fibrin is crosslinked by fXIIIa
D-dimers indicate the activation of thrombin and plasmin, and are specific for active coagulation and fibrinolysis

44
Q

Which is true?
A The endpoint of all clotting assays (PT, aPTT, ACT) is based on the platelet attachment.
B These tests usually are not prolonged until fibrinogen is severely decreased (<150 mg/dL)
C With TEG, the angle (K) is dependent largely on platelets
D With TEG, the maximum amplitude (MA) represents the ultimate strength of the fibrin clot

A

A formation of fibrin clot
B <50-100 mg/dL
C alpha, largely dependent on fibrinogen as well as platelets
D true

45
Q

Which of the following is true?
A FFP contains only vWF, factor VIII, fibrinogen, fibronectin
B Cryoprecipitate can be used for Vitamin K deficiencies
C Fresh whole blood is the primary means of platelet transfusion in veterinary practice
D DDAVP works at the V1 receptors

A

A FFP contains coagulation proteins, vWF, natural anticoagulant, albumin, globulins
(Cryoprecipitate specifically contains vWF, factor VIII, fibrinogen, fibronectin)
B Cryosupernatent or FFP can be used for Vitamin K deficiencies
C TRUE
D DDAVP works at the V2 receptors→ release of vWF AND increases platelet fxn

46
Q

T/F? Type II von Willebrand disease is the most common form in dogs and is characterized by an almost complete absence of vWF

A

FALSE Type I von Willebrand disease is the most common form in dogs characterized by presence of all multimers, but in reduced concentrations
Type II characterized by DISPROPORTIONATE LOSS high molecular weight multimers
Type III is characterized by an almost complete absence of vWF

47
Q

What of the following is false regarding hepatic associated hemorrhage
A The liver plays a pivotal role in the synthesis of clotting factors with the exception of factor VIII
B Decreased factor synthesis occurs with only > 70% decrease in hepatic function
C PTT is increased first in hepatic associated coagulopathy
D Liver biopsy associated hemorrhage is more common in canine patients with a PLT count <86k and prolonged clotting times

A

C PTT is DECREASED first in hepatic associated coagulapathy

48
Q

Name the three parts of Virchow’s triad!

A

Vessel wall abnormalities/endothelial injury
Abnormalities of flow / stasis
Hypercoagulability/abnormalities of blood constituents

49
Q

True or false: pulmonary thromboembolism is the most common postoperative thromboembolic complication with profound respiratory and cardiovascular compromise

A

True

50
Q

anticoagulants and mechanism of action: Warfarin

A

Warfarin→ Vitamin K antagonist that alters the synthesis of vitamin K-dependent coagulation factors II, VII, IX, X, protein S and C

51
Q

Other anticoagulants and mechanism of action: Dabigatran; apixaban

A

Novel oral anticoagulants
Dabigatran→ reversible direct thrombin inhibitor
Rivaroxaban, apixaban and edoxaban→ direct fXa inhibitors

52
Q

anticoagulants and mechanism of action: heparin

A

Unfractionated and low-molecular-weight heparin→ Potentiation of antithrombin activity, leading to the inactivation of coagulation factors, notably thrombin and fXa

53
Q

antiplatelets drug+ MOA: aspirin, clopidogrel

A

Aspirin→ irreversible functional defect in platelets by inactivating COX-1, thus suppressing the synthesis of TxA2
Clopidogrel→ irreversibly blocks adenosine diphosphate (ADP) binding to its P2Y12 receptor on the platelet surface

54
Q

False for DIC?
A Mortality rates of 50% to 77% are reported in dogs, and 93% in cats.
B Sepsis and systemic inflammatory response syndrome (SIRS) are the most common causes in human and dogs.
C Dogs with DIC were hypercoagulable as determined by thromboelastography; only 22% were hypocoagulable.
D Bleeding occurs in a majority of patients with DIC; organ dysfunction is less common.

A

D minority of p, MODS MORE common

55
Q

False for DIC?
A The cornerstone of DIC management includes specific and vigorous treatment of the underlying condition.
B Adequate perfusion must be restored and maintained to alleviate the vascular stasis, hypoxia, and acidosis that promote coagulation activation.
C Early enteral nutrition and aggressive management of GI ulceration is recommended.
D Fresh frozen plasma transfusion, providing two times normal antithrombin activity.

A

D FFP transfusion has been recommended for vet patients with DIC but this practice is not supported by evidence.
A beneficial effect of antithrombin supplementation necessitates the administration of a sufficient plasma volume to increase antithrombin activity to 1.5 to 2.0 times normal.432 Even large doses of fresh frozen plasma do not achieve these levels in human beings or in dogs.

Tobias Sec I-III Sample Questions (18 decks)

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