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Biochem exam 3 > Coagulation- A surgical perspective > Flashcards

Coagulation- A surgical perspective Flashcards

1
Q

the 3 phases of normal hemostasis:

A
  1. vascular phase
  2. platelet plug
  3. coagulation phase
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2
Q

What is the vascular phase of hemostasis?

A

vasconstriction occurs
-diminish the blood flow to the damaged area

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3
Q

What happens during the platelet phase of hemostasis?

A
  1. exposed collagen binds and activates platelets
  2. release of platelet factors
  3. attract more platelets
  4. aggregate into platelet plug
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4
Q

What do the platelets bind to at the site of injury?

A

collagen

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5
Q

What causes platelets to change their shape?

A

presence of fibrinogen

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6
Q

What does the conformational change of platelets allow?

A

aggregation to form a primary platelet plug

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7
Q

which pathway is longer (extrinsic or intrinsic)?

A

intrinsic

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8
Q

What factor is the beginning of the common pathway?

A

Factor X

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9
Q

Common pathway of coagulation:

A

Factor X
-prothrombin to thrombin
fibrinogen to fibrin

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10
Q

What does fibrin do to the platelet plug?

A

allows for tight binding and forms a more stable hemostatic plug

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11
Q

What is clot dissolution?

A

partial of complete dissolution of a hemostatic plug by plasma

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12
Q

What are some factors that affect normal hemostasis mechanism?

A

-vessel wall integrity
-adequate number of platelets
-proper functioning platelets
-adequate levels of clotting factors
-proper function of fibrinolytic pathway

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13
Q

What are common lab tests done to test hemostasis?

A

-platelet count (in a CBC)
-bleeding time
-coagulation profile
* PT- prothrombin time
* APTT- activated partial thromboplastin time
* INR- international normalized ratio

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14
Q

What is a platelet function test?

A

test done to identify platelet dysfunction
-may be recommended for those that bruise easily, bleed excessively, or take medications that can alter platelet function

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15
Q

What is a clotting factor assay?

A

test that measures the level or functional activity of one or more coagulation factors

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16
Q

What is a normal platelet count?

A

150,000-400,000 cells/ mm

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17
Q

What level of platelets is considered thrombocytopenia?

A

100,000-140,000

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18
Q

What level of platelets is considered mild thrombocytopenia?

A

50,000-100,000

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19
Q

What level of platelets is consider severe thrombocytopenia?

A

<50,000

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20
Q

What level of platelets is considered spontaneous bleeding?

A

<20,000

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21
Q

What is a normal bleeding time?

A

2-9 minutes

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22
Q

What is a bleeding time considered to have platelet dysfunction?

A

9-15 minutes

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23
Q

What does a prothrombin time test measure?

A

effectiveness of extrinsic pathway
-conversion of VII to VIIa

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24
Q

What is a normal prothrombin time?

A

12-13 seconds

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25
Q

Common causes of prolonged prothrombin time:

A

-warfarin use
-vitamin K deficiency
-liver disease

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26
Q

What does an activated partial prothrombin time test measure?

A

effectiveness of intrinsic and common pathway
-more sensitive than PTT

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27
Q

What is a normal aPTT result?

A

30-40 seconds

28
Q

What aPTT level signifies spontaneous bleeding?

A

more than 70 seconds

29
Q

What are common causes of prolonged aPTT?

A

-congenital deficiency of intrinsic clotting factors
-von Willebrand disease
-liver cirrhosis
-Vitamin K deficiency
-heparin therapy

30
Q

How to calculate international normalized ratio:

A
31
Q

What is a normal INR?

A

0.8-1.2

32
Q

What is an INR of someone on anticoagulants?

A

2-3.5

33
Q

Why would an INR range of 2-3 be ideal?

A

if the patient has a history of
-atrial fibrillation
-ischemic stroke
-systemic embolism
-mitral stenosis
-planned cardioversion
-following open heart surgery

34
Q

Are acquired or congenital bleeding disorders more common?

A

acquried

35
Q

What three congenital bleeding disorders account for 90% of congenital bleeding disorders?

A

Hemophilia A and B and Von Willebrand’s disease

36
Q

What causes hemophilia A?

A

deficiency in clotting factor VIII

37
Q

What causes hemophilia B?

A

deficiency in clotting factor IX

38
Q

Prevalence of Hemophilia A

A

1 in 10,000

39
Q

Prevalence of Hemophilia B

A

1 in 50,000

40
Q

How is hemophilia inherited?

A

x linked recessive
-25% have no family history?? weirddddd

41
Q

Does hemophilia affect males or females more?

A

males

42
Q

Three levels of hemophilia:

A

mild
moderate
severe

43
Q

Characteristics of Mild hemophilia:

A

-only have issues have serious injury, trauma, or surgery
-first episode may not occur until adulthood

44
Q

Characteristics of Moderate hemophilia:

A

-15% of hemophilia population
-tend to have bleeding episodes after injury
-may have ‘spontaneous bleeding episodes’

45
Q

Characteristics of Severe hemophilia:

A

60% of hemophilia population
-frequent spontaneous bleeding episodes
-often in the joints and muscles

46
Q

Treatment for patients with hemophilia:

A

A- cyroprecipitate and factor VIII concentrate
B- factor IX concentrate

47
Q

What is cyroprecipitate?

A

only adequate fibrinogen concentrate available for intravenous use
-made from plasma and contains fibrinogen, von Willebrand factor, factor VIII, factor XIII, and fibronectin

48
Q

What type of anesthesia should be avoided in patients with hemophilia?

A

block local anesthetic

49
Q

in mild hemophilia, what can be used to increase factor VIII coagulant activity?

A

vasopressin analogue- desmopressin

50
Q

What can be used to extract teeth in patients with hemophilia?

A

epsilon-aminocaproic acid or tranexamic acid

51
Q

what does epsilon-aminocaproic acid and tranexamic acid do?

A

inhibit fibrinolysis

52
Q

What is von Willebrand disease?

A

bleeding disorder where von Willebrand factor is missing or does not function properly
-does not allow proper platelet interactions

53
Q

von Willebrand disease type 1

A

shortage of von Willebrand factor
-mild
-70-80% of cases
-most common

54
Q

von Willebrand disease type 2

A

flawed von Willebrand factor
-usually mild
-2 types 2A and 2B
-20-25% of cases

55
Q

von Willebrand disease type 3

A

complete lack of von Willebrand factor
-more severe
-very rare
-1 in 500,000 people

56
Q

Are there blood tests to determine von Willebrand disease?

A

yes
-bleeding time
-VWF activity level
-VWF antigen levels
-genetic testing

57
Q

Why is demsopressin given to those with VWD?

A

increases production of von willebrand factor

58
Q

What type of von Willebrand disease should not be treated with desmopression?

A

type 2B

59
Q

What can cause thrombocytopenia ?

A

decreased platelet production or increased platelet destruction

60
Q

What causes decreased platelet production?

A

myelosuppresion due to antieoplastic agents as well as radiation treatment

61
Q

Local measures to achieve hemostasis

A

-suture the wound
-pressure with oral packs

62
Q

What can cause acquired bleeding disorders?

A

drugs, alcohol, virus induced liver disease, vitamin K deficiency from antibiotic use, acquired platelet function defect, multiple myeloma, oral anticoagulants, antiplatelets, leukemia, chemotherapy, HIV patients, and kidney failure

63
Q

What needs to be done to treat a patient with a bleeding disorder?

A

-medical consult
-assess lab test results
-refer to oral surgery
-stop using anticoagulants/antiplatelets prior to surgery
-bridging therapy
-local measures to control bleeding

64
Q

Examples of anti platelet medications

A

-plavix
-aspirin
-effient

65
Q

Examples of anticogulant medication?

A

-warfarin
-lovenox
-pradaxa
-eliquis
-xarelto

66
Q

Can a dentist tell a patient to stop taking their antiplatelet/anticoagulants?

A

no
-the prescribing physician is in charge of these decisions

67
Q

What can be used to irrigation of wound for those with bleeding disorders ?

A

tranexamic acid mouth wash

Biochem exam 3 (10 decks)

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