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Human Systems and Anatomy > clotting > Flashcards

clotting Flashcards

1
Q

what are the components of blood involved in clotting

A

coagulation factors and platelets

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2
Q

describe the coagulation process

A
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3
Q

which medications can affect clotting

A
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4
Q

what are the most common inherited blood disorders

A
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5
Q

describe the importance of clotting in dentistry

A
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6
Q

what are the stages to clotting

A

injury to a vessel
vascular phase, whereby the vessel attempts to stop the bleeding
platelet phase aka primary haemostats
coagulation phase aka secondary haemostats
clot formation and stabilisation
clot dissolution

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7
Q

describe the vascular phase of clotting

A

this is when the vessel attempts to stop the bleeding
the vessel will vasoconstriction, via smooth muscle action.
injury exposes the collagen in the blood vessel wall, and the fibres will kickstart the healing process.

there is release of factors from the endothelial cells lining the vessel, which includes
- adp platelets
- tissue factor
- endothelins

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8
Q

describe the platelet phase of clotting

A

this is when the exposed collagen, apd and endothelins attract platelets.
the platelets become sticky and adhere to each other, causing a platelet plug via aggregation.

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9
Q

how does the platelet plug form

A

the exposed collagen released ADP and endothelia’s which attracts the platelets.
there is platelet adhesion and aggregation, which leads to more adp and thromboxane a2 being released which attracts more platelets. this is positive feedback.
this plugs the vessel injury but is a temporary solution, as the weaker repair compared to the finished product

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10
Q

what is the aim of the coagulation phase

A

to create a more permanent, robust clot

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11
Q

what is the clot made from

A

fibrin

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12
Q

what is the coagulation cascade

A

a series of proteins ultimately leads to clot formation through two separate pathways; intrinsic and extrinsic
parallel to this is fibrinolysis which is clot breakdown to prevent spontaneous clotting in health

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13
Q

where does the intrinsic coagulation cascade occur

A

in the bloodstream

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14
Q

where does the extrinsic coagulation cascade occur

A

in the vessel wall

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15
Q

what are some medications that affect platelets

A

aspirin
clopidogrel
dipyridamole
ticagrelor

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16
Q

what are some medications that act as anti coagulants

A

warfarin
edoxaban
rivaroxaban
apixaban
dabigatran

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17
Q

why would someone be prescribed a blood thinner

A

coronary disease to prevent myocardial infarction or stroke
peripheral artery disease to reduce symptoms
prosthetic heart valves to prevent a clot
atrial fibrillation to prevent a stroke
pulmonary embolisms and deep vein thrombosis to treat or prevent the conditions
following surgery or pregnancy

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18
Q

what is coronary artery disease

A

narrowing of the vessels supplying blood to the heart

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19
Q

what is peripheral artery disease

A

narrowing of the vessels supplying the legs or the arms

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20
Q

what is atrial fibrillation

A

heart arrhythmia

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21
Q

how many mg aspirin a day

A

75mmg

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22
Q

how many mmg aspirin is given in acute myocardial infarction or in a stroke

A

300mmg

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23
Q

what is the mechanism of action of aspirin

A

inhibits the COX enzyme, reducing production of thromboxane A2, thereby reducing the platelet aggregation

interfering with the canalisation of the formation of thromboxane a2 prevents platelet aggregation, which is irreversible, and the platelets live for 7-10 days. should be familiar with this mechanism of action. the membrane f the platelet will begin to break down

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24
Q

do people need to stop taking aspirin for dental treatment

A

no

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25
Q

what is the lifespan of platelets

A

7-10 days

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26
Q

what is the common dose of aspirin

A

75 mmg

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27
Q

what is aspirin used for

A

preventing blood clots in vessels when they are narrowed due to atherosclerotic disease

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28
Q

what are some conditions requiring 75mmg aspirin a day

A

coronary artery disease, secondary prevention
transient ischaemic attack, secondary prevention

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29
Q

describe warfarin

A

this drug is used less nowadays but it inhibits the production of vitamin k which is essential in formation of coagulation factors 2, 7, 9 and 10.
used for prosthetic heart valve patients as they have a risk of clotting due to blood stagnation

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30
Q

what is the INR

A

international normalised ratio used to monitor warfarin

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31
Q

what are the indications with medications and food stuffs observed in warfarin

A

metronidazole
fluconazole
NSAIDs
alcohol
grapefruit

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32
Q

describe DOACs

A

these are direct oral anticoagulants including ecoxaban, rivaroxaban, apixaban, dabigatran

these are taken over from warfarin for conditions such as atrial fibrillation, PE and DVT

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33
Q

what is the mechanism of action of DOACs

A

inhibits factor Xa and inhibits free thrombin

34
Q

does DOAC require monitoring

A

no

35
Q

compare warfarin vs DOACs for onset

A

slow vs rapid

36
Q

compare warfarin vs DOACs for dosing

A

variable vs fixed

37
Q

compare warfarin vs DOACs for food effect

A

yes vs no

38
Q

compare warfarin vs DOACs for drug interactions

A

many vs a few

39
Q

compare warfarin vs DOACs for monitoring

A

yes vs no

40
Q

compare warfarin vs DOACs for offset

A

long vs shorter

41
Q

describe injectable anticoagulants

A

used after giving birth or during long hospital stays
or where patients are unable to take DOACs

42
Q

what is the mechanism of action of injectable anticoagulants

A

inhibits the formation of factor Xa and thrombin

43
Q

what are some injectable anticoagulants

A

dalteparin
enokaparin

44
Q

what are the general principles for dentistry and anti coagulant medications

A

delay dental treatment until the anticoagulant plan finishes
plan treatment for early in the week and in the day
atraumatic surgery
consider packing and suturing
ensure bleeding has stopped
advise paracetamol for pain relief

45
Q

what are bleeding disorders

A

these are disorders where there is impairment of the different elements of clotting, like the platelets, clotting factors or in liver disease

46
Q

what are some acquired bleeding disorders

A

liver disease
thrombocytopenia

47
Q

what are some inherited bleeding disorders

A

von willebrand disease
haemophilia A
haemophilia B

48
Q

describe liver disease in relation to bleeding disorders

A

can result in a bleeding tendency due to reduced platelet numbers and function
the thrombopoeitin hormone stimulates platelet production and is produced in the liver
there is also impaired production of coagulation factors

49
Q

describe thrombocytopenia

A

this is when there are low platelet numbers due to reduced production or increased destruction

50
Q

how does reduced platelet production occur

A

b12 deficiency
folic acid deficiency
liver disease
leukemia
chemotherapy

51
Q

how does increased destruction of platelets occur

A

immune drive, top or heparin induced thrombocytopenia

52
Q

describe von willebrand disease

A

this is the most common inherited cause of abnormal and prolonged bleeding
an autosomal dominant inheritance, causing an absent or defective von willebrand factor
this leads to impaired platelet aggregation and impaired transport of factor 8 to the wound

53
Q

what is type 1 von willebrand

A

this involves partial deficiency of von willebrand factor, the most common and mildest type

54
Q

what is type 2 von willebrand

A

this involves reduced function of von willebrand disease

55
Q

what is type 3 von willebrand disease

A

this involves a complete deficiency of von willebrand factor and is the most rare and severe type

56
Q

what is the inheritance type of each von willebrand disorder

A

type 1 is autosomal dominant
type 2 is autosomal dominant
type 3 is autosomal recessive

57
Q

describe von willebeand disease in dentistry

A

does not require daily treatment, but for dental treatment likely to cause bleeding, should cover with:
- tranexamic acid mouthwash if disease is mild and the procedure is low risk
- DDAVP/desmopressin if more likely to cause bleeding
- von willebrand factor concentrate if severe disease and high risk procedure

58
Q

how does DDAVP and desmopressin work

A

increases von willebrand factor production and factor 8 production

59
Q

describe the inheritance pattern of haemophilia

A

x linked recessive, primarily affecting males

60
Q

describe haemophilia A

A

this affects deficiency factor 8

61
Q

describe haemophilia B

A

this affects deficiency of factor 9

62
Q

what does haemophilia present as

A

spontaneous bleeding into joints and significant bleeding following minor trauma

63
Q

how is haemophilia A treated

A

DDAVP/desmopressin or factor 8 concentrate if more severe

64
Q

how is haemophilia B treated

A

factor 9 concentrate, as DDAVP is not effective

65
Q

how long before dental treatment should blood products be given to haemophiliac patients

A

30 minutes

66
Q

factor percentage of severe haemophilia

A

less than 1%

67
Q

factor percentage of moderate haaemophilia

A

2-5%

68
Q

factor percentage of mild haemophilia

A

6-40%

69
Q

describe dental treatment for severe haemophilia

A

enhanced preventative advice and treatment
all treatment except for prosthetics carried out in hospital setting

70
Q

describe dental treatment for moderate haemophilia

A

enhanced preventative advice and treatment
manage as for severe haemophilia

71
Q

describe dental treatment for mild haemophilia

A

enhanced preventative advice and treatment
not all treatments in hospital , seen every two years in specialist dental team at haemophilia centre

72
Q

what to note when administering local anaesthetic to bleeding disordered patients

A

avoid the inferior alveolar nerve block as there is risk of bleeding from the. muscle. can lead to haematoma or airway compromising

73
Q

what administration for local anaesthetic is preferred for patients with bleeding disorders

A

buccal infiltration
intra papillary injections
intra ligamentary injections

74
Q

what are the four blood tests related to clotting

A

full blood count
liver function est
inr
coagulation screen

75
Q

what is the full blood count

A

counting red cell, white cell and platelet

76
Q

what is the liver function test

A

this shows the acute liver damage
most coagulation factors are made in the liver
less helpful about specific synthetic function

77
Q

what is the INR

A

the international normalised ratio used to compare how long it takes patients blood clotc compared to laboratory standard
the higher the number, the longer it takes to clot
usual range for patients on warfarin is 2-4
healthy person on no medication is 1
normally should be less than 4 for medical treatment

78
Q

what is coagulation on screen

A

this looks at intrinsic and extrinsic pathways and gives good insight into livers synthetic function

79
Q

what is thrombophilia

A

too much clotting
there are elements of the clotting cascade that prevent over clotting, protein c, protein s and antithrombin.
antiphospholipid syndrome or deficiency of protein c or s can lead to over clotting

80
Q

what are some conditions featuring over clotting

A

pulmonary embolism (blood clot in the lung)
deep vein thrombosis (blood clots in the limbs, often in the leg)

81
Q

what are the risk factors for thrombophilia

A

previous DVT/PE
prolonged immobility
plaster cast
combined oral contraceptive pill
surgical operation
acutely unwell eg sepsis
cancer
dehydration
pregnancy

82
Q

how is thrombophilia managed

A

anticoagulant medications - making them a bleeding risk in dental practice

Human Systems and Anatomy (57 decks)

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