Coagulation

Question 1

Primary hemostasis occurs within seconds after a vascular injury. Platelets become activated and adhere to the subendothelial collagen layer of the denuded vessel via glycoprotein receptors; this
interaction is stabilized?

Answer 1

von Willebrand’s factor (vWF)

Question 2

Collagen and epinephrine activate

____ and ____ in the platelet plasma membrane, resulting in formation of _____ and degranulation, respectively.

Answer 2

Phospholipases A and C
Thromboxane A2 (TXA2)

Question 3

Instrinsic and extrinsic pathways mechanisms merge after formation of what clotting factor?

Answer 3

X

Question 4

When a clot is formed, plasminogen is incorporated and then converted to plasmin by (2)?

Answer 4

1) Tissue plasminogen activator (tPA)

2) Fragments of factor XII

Question 5

Coagulation inhibitors that are normally present in plasma (3)?

Answer 5

1) Antithrombin III
2) Proteins C and S
3) Tissue factor pathway inhibitor

Question 6

Normal bleeding times range from __ to __

minutes, and a bleeding time >1.5 times normal (>15 minutes) is considered significantly abnormal.

Answer 6

4-9 minutes

Question 7

The minimal recommended platelet count before surgery is?

Answer 7

75,000/mm3

Question 8

Factor VIII is a large protein complex of two noncovalently bound factors (2)?

Answer 8

Factor VIII antigen and vWf

Question 9

In vivo, coagulation is initiated primarily by contact of factor __ with extravascular tissue.

Answer 9

VII

Question 10

The primary treatment for DIC is to?

Answer 10

Treat the underlying medical condition

Question 11

What pathway is affected first by vitamin K deficiency?

Answer 11

Extrinsic

Because the factor with the shortest half-life is factor VII, found only in the extrinsic pathway.

Question 12

Nice to know

Answer 12

The warfarin-like drugs compete with vitamin K for binding sites on the hepatocyte.

Administration of subcutaneous vitamin K reverses the functional deficiency in 6 to 24 hours.

With active bleeding or in emergency surgery, fresh frozen plasma (FFP) can be administered for immediate hemostasis.

Question 13

The half-life of heparin’s anticoagulant effect is about ___ minutes in a normothermic patient.

Answer 13

90 minutes

Question 14

Heparin is a polyanionic mucopolysaccharide that accelerates the interaction between _____ and the activated forms of factors (5)?

Answer 14

antithrombin III

II, X, XI, XII, and XIII

Question 15

This test adds fresh whole blood to a test tube already containing an activator. It is widely used to monitor heparin therapy in the operating room. The normal range is 90 to 120 seconds.

Answer 15

Activated clotting time

Question 16

A test that measures the extrinsic and common pathways. Tissue thromboplastin is added to the patient’s plasma.

Answer 16

Prothrombin time (PT)

Question 17

A test was introduced to improve the consistency of oral anticoagulant therapy.

Answer 17

International normalized ratio (INR)

Question 18

What are the indications for administering fresh frozen plasma?

Answer 18

When microvascular bleeding is noted and PT or PTT exceeds 1.5 the control value, FFP should be considered. The usual dose is 10 to 15 ml/kg. FFP will also reverse the anticoagulant effects of warfarin (5 to 8 ml/kg).

Question 19

Administration of vitamin K will have the same result as FFP but will take how many hours take effect?

Answer 19

6-12 hours

Question 20

It is the cold-insoluble white precipitate formed when FFP is thawed. It contains what clotting factors?

Answer 20

Cryoprecipitate

VIII, vWf, fibrinogen, XIII

Question 21

One unit of cryoprecipitate per 10 kg of body weight will increase fibrinogen levels by ___ mg/dl

Answer 21

50

Question 22

Cryoprecipitate lacks what factor?

Answer 22

V

Question 23

The basic difference between the intrinsic and extrinsic pathways is the phospholipid surface. What is found in extrinsic?intrinsic?

Answer 23

platelet phospholipid (intrinsic pathway) 
tissue thromboplastin (extrinsic pathway)

Question 24

What measures the instrinsic pathway?

Answer 24

PTT measures the clotting ability of all factors in the intrinsic and common pathways except factor XIII

Question 25

Describe the activated partial thromboplastin time.

Answer 25

Maximal activation of the contact factors (XII and XI) eliminates the lengthy natural contact activation phase and results in more consistent and reproducible results.

Question 26

This is a neoantigen formed by the action of thrombin in converting fibrinogen to cross-linked fibrin.

Answer 26

D-dimer

Question 27

It measures the viscoelastic properties of blood as it is induced to clot in a low shear environment resembling venous flow, providing some measure of clot strength and stability, including the time to initial clot formation, the acceleration phase, strengthening, retraction, and clot lysis.

Answer 27

Thromboelastography (TEG)

Question 28

Discuss the parameters measured by thromboelastography. There are five parameters of the TEG tracing?

Answer 28

1) R
2) k
3) alpha angle
4) MA
5) MA60

Question 29

Thromboelastography parameter that time from the initiation of the test to initial fibrin formation?

Answer 29

R

Question 30

Time from the beginning of clot formation until the amplitude of TEG reaches 20 mm, representing the dynamics of clot formation

Answer 30

k

Question 31

Angle between the line in the middle of the TEG tracing and the line tangential to the developing body of the tracing, representing the kinetics of fibrin
cross-linking

Answer 31

alpha angle

Question 32

Reflects the strength of the clot, which depends on the

number and function of platelets and their interaction with fibrin.

Answer 32

MA (maximum amplitude)

Question 33

Measures the rate of amplitude reduction 60 minutes after MA, representing the stability of the clot

Answer 33

MA60