Hemostatic monitoring

Question 1

What is PROVETS?

Answer 1

Partnership on Rotational ViscoElastic Test Standardization?

Question 2

How should samples be prepared before ROTEM or TEG analysis?

Answer 2

cirtrated 1:9 and wait at room temp for 30 min

Question 3

What are the 3 phases of viscoelastic testing?

Answer 3

• Initiation - precoagulation - beginning of analysis until first strands of fibrin are formed
• stabilization - end of initiation until wides separation - formation of the clot
• lysis - fibrinolysis

Question 4

What are CT/R and what are they influenced by?

Answer 4

Clotting time (ROTEM), Reaction time (TEG)
time from test activation until clot firmness of 2 mm

dogs
* hematocrits
* plasma FV, FVII, FIX, FX concentrations

Question 5

What are CFT/K and what are they influenced by?

Answer 5

Clot formation time (ROTEM), K (TEG)
time from end of CT/R until clot firmness of 20 mm

dog
* hematocrit
* Platelet count
* plasma fibrinogen and FV concentrations

Question 6

What is the alpha angle and what is it influenced by?

Answer 6

• 2mm to 20mm mark line as angle

dog:
* hematocrit
* platelet count
* plasma fibrinogen, FV and FIX

Question 7

What is MCF/MA and what is it influenced by?

Answer 7

MCF (ROTEM), MA (TEG)

maximum amplitude of the clot, expressed in mm

dog:
* hematocrit
* platelet count
* plasma fibrinogen concentration

Question 8

How is fibrinolysis quantified in TEG or ROTEM?

Answer 8

TEG: Ly30, Ly45, Ly60
ROTEM: Li30, Li45, Li60

percentage you get is how much of the clot is lyzed (how much of the clot firmness is lost)

Question 9

What are the reference ranges for the coagulation index in dogs?

Answer 9

greater than 4 - hypercoagulable
less than - 4 hypocoagulable

Question 10

What activators are added for exTEM or inTEM ROTEMs?

Answer 10

exTEM: Tissue factor
inTEM: ellagic acid

intrinsic pathway TEG: kaolin or ellagic acid

Question 11

How reliable are viscoelastic tests to detect hyperfibrinolysis?

Answer 11

lack of sensitivity reported in comparison with D-dimer or FDP plasma cc

Question 12

Can you use viscoelastic testing to monitor heparin therapy?

Answer 12

Not recommended

use of LMWH was not associated with significant alterations of TEG or ROTEM in dogs or cats

Question 13

List 4 ways of measuring platelet counts

Answer 13

impedence analyzer
laser flow cytometers
quantitative buffy coat analyzers
peripheral blood smear

Question 14

what values appear on a thrombogram?

Answer 14

• PLT count
• mean platelet volume (MPV) - increased values show increased production/young PLT, decreased can indicate immune mediated destruction
• Platelet distribution width - shows platelet anisocytosis
• platelet morphology
• thrombocrit (plateletcrit)

Question 15

In what ways can impedence analyzers count platelets incorrectly

Answer 15

• separate cells based on size - large platelets or small RBC may overlapp and be counted wrongly - especially an issue in cats
• clumps of PLTs may be counted as leukocytes

flow cytometer is more reliable - measures cells according to internal complexity

Question 16

What is a normal BMBT?
Other than primary hemostasis, what can alter the results?

Answer 16

less than 4 min in dogs, less than 1.5 min in cats (2 min in different reference)

severe anemia or polycythemia - change blood viscosity

Question 17

What is the gold standard for assessing PLT function?

Answer 17

turbidimetric aggregometry

Question 18

List all factors evaluated by PT.

Answer 18

• FVII
• FX
• FV
• FII
• FI

Question 19

What is thromboplastin?

Answer 19

combination of phospholipids and TF

Question 20

What factors are assessed by aPTT?

Answer 20

• FXI
• FXII
• FIX
• FVIII
• FX
• FV
• FII
• FI

Question 21

How much factor activity may be lost before PT and aPTT appear prolonged?

Answer 21

60-70%

Question 22

Is PT or aPTT prolonged in vWD and why?

Answer 22

aPTT - because FVIII is affected

Question 23

What is the half-life of VII in dog and how soon after vitamin K antagonist ingestion is PT typically prolonged?

Answer 23

6.2 hours
24-36 hours later

Question 24

How do machines measure PT/aPTT

Answer 24

clot is detected via light-emitting diode optical detectors

PT/aPTT recorded when movement of blood falls below predetermined value

Question 25

What is added to the sample to measure PT or aPTT?

Answer 25

PT - thromboplastin, calcium
aPTT - contact pathway activator, phospholipods, calcium

Question 26

List examples for contact pathway activators

Answer 26

• ellagic acid
• kaolin
• silica

Question 27

What are differentials for a shortened PT?

Answer 27

• hypercoagulable stage
• inflammation causing high fibrinogen cc (will shorten aPTT too)
• TF increase in sample from venipuncture
• normal range for the patient
• excessive plasma-to-anticoagulant ratio

Question 28

What does ACT evaluate?

Answer 28

intrinsic and common pathway

Question 29

By what percentage do coagulation factor activities need to drop to causee increased ACT?

Answer 29

85-95%

Question 30

What do grey-top vacutainers contain and what are they used for?

Answer 30

diatomaceous earth - ACT

Question 31

What is whole-blood clotting time?

Answer 31

whole blood added to a glas tube without anticoagulants

normal animals - should clot within 3-13 minutes

once formed clot should retract to 50% within 1-2 hours