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Haematological disease (Den 303) > Anticoagulation > Flashcards

Anticoagulation Flashcards

1
Q

Thrombosis

A

Blood in blood vessels should be fluid

Inappropriate blood coagulation within a vessel is called thrombosis

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2
Q

Bleeding

A

Appropriate blood coagulation occurs when blood escapes from a vessel (failure of this results in bleeding)

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3
Q

Two types of thrombosis

A 
In arterial circulation
-high p system
-platelet rich
In venous circulation
-low p system
-fibrin rich
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4
Q

Thrombosis treatment

A

Arterial thrombosis
-antiplatelet drugs
Venous thrombosis
-anticoagulant drugs

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5
Q

Guideline for anticoagulant management and dental surgery

A

Many guidelines
Scottish Dental Clinical Effectiveness Guideline
-evidence based
-DOAC guideline less cautious than other guidelines

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6
Q

Antiplatelet drugs

A

Aspirin
Copidogrel
Prasugrel
inhibit platelets irreversibly

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7
Q

Aspirin

A

Inhibits cyclo-oxygenase (platelet enzyme) irreversibly

Act for lifetime of platelet ie 7-10 days

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8
Q

Clopidogrel

A

Blocks ADP receptor (on platelet surface) irreversibly

Acts for lifetime of platelet ie 7-10 days

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9
Q

Prasugrel

A

Blocks ADP receptor irreversably
Acts for lifetime of platelet ie 7-10days
More rapid and consistent inhibition than clopidogrel

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10
Q

Antiplatelet drugs and dental procedures

A

Need to balance risk of bleeding vs risk of thrombosis if drugs are discontinued
Antiplatelet medications do not have to be stopped before primary care dental surgical procedures

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11
Q

Anticoagulants

A

IV
SC
Oral (most important for us)

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12
Q

IV anticoagulants

A

Unfractioned heparin

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13
Q

SC anticoagulants

A

Low molecular weight heparins e.g. enoxaparin, tinzaparin, dalteparin

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14
Q

Oral anticoagulants

A

Warfarin
Dabigatran, rivaroxaban, apixaban, edoxaban
-becoming more important

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15
Q

Heparin

A

Glycoseaminoglycan derived from porcine mucosa
Binds to antithrombin and > its activity
Indirect thrombin inhibitor (since it acts by enhancing the activity of antithrombin)

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16
Q

Heparin given by

-monitored by

A

Given by continuous infusion
Hospital patients only
Monitor with the APTT test
-aim for ratio 1.8-2.8

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17
Q

Low molecular weight heparin

A 
Smaller molecule made from unfractionated heparin
Given SC
Renally excreted
Given once daily
Weight adjusted dosing
No monitoring necessary
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18
Q

Low molecular weight heparin used for

A

Treatment and prophylaxis
In Sheffield – Dalteparin is used
For dental work give last dose 24 hours before dental surgery
Next dose 4 hours after dental surgery

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19
Q

Warfarin: pharmcology

A 
Given by mouth completely and rapidly absorbed 
99% plasma protein bound
Inhibits the production of 
-factors II, VII, IX, X 
-protein C and protein S
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20
Q

Warfarin is metabolised by

A

The liver via cytochrome P450

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21
Q

Peak effect of warfarin

A

3-4 days after starting, effect still present 4-5 days after stopping
-i.e. slow on and off action

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22
Q

Warfarin: interactions

A

Potentiation of anticoagulation

Inhibition of anticoagulation

23
Q

Potentiation of anticoagulation

A

< warfaring binding to albumin e.g. Phenytoin

Inhibition of hepatic microsomal degradation of warfarin e.g. erythromycin

24
Q

Inhibition of anticoagulation

A

Acceleration of hepatic microsomal degradation of warfarin e.g. Carbamazepine
Enhanced synthesis of clotthing factors e.g. Vit K

25
Q

Warfarin: monitoring

A

The test to do is INR (International Normalised Ratio)
Dose of warfarin based on INR
Frequency of monitoring depends on stability of the pt’s INR
-eg can be 1/week - 1/ 8 weeks.
INR must be measured before surgery or invasive procedures
Can be measured using a near pt testing device
Uses a drop of blood, similar to blood glucose measurement
-dentists can get these to avoid pts having to go to hospital

26
Q

Anticoagulation target

A 
INR 2.0-3.0
-treatment of DVT/PE (6 months)
-atrial fibrillation (life-long)
INR 3.0-4.5
-recurrent DVT/PE on warfarin (life-long)
-mechanical Heart Valves (life-long)
27
Q

Warfarin: side effects

A

Bleeding
Skin necrosis (only at start of treatment)
Embryopathy (if used in first trimester of pregnancy)

28
Q

Annual risk of bleeding from warfarin

A

3% any bleeding
1% serious/ life-threatening
0.3% death due to bleeding

29
Q

Warfarin: reversal

A

Stop warfarin
Vitamin K (IV, SC, O)
Fresh Frozen Plasma (FFP)
Clotting Factor Concentrate

30
Q

Stop warfarin

A

Takes 2-3 days

31
Q

Vitamin K (IV, SC, O)

A

With IV preparation 80% correction in 6 hours

32
Q

Fresh Frozen Plasma (FFP)

A

Need large volume, only partial correction

33
Q

Clotting Factor Concentrate

A

Contains factors II, VII, IX, X

Complete correction in 10mins

34
Q

Warfarin: warnings to patients

A

No IM injections
No aspirin, NSAID without consultation
No contact sports – otherwise normal activities
Moderate alcohol intake is not harmful but excessive alcohol intake (binging) is
Significant changes in diet should be reported
Consult doctor or pharmacist before any new medication including over-the-counter drugs

35
Q

Dental extractions and warfarin

A

Used to stop warfarin before procedures
20 years ago SR
-no thromboses if continued warfarin
-12 episodes of “serious” bleeding i.e. 0.2% for pts with therapeutic INR but INR was not checked before hand
-discontinued anticoagulation: no serious bleeding but 2 thrombotic episodes (stroke) i.e. 0.4%
–> go ahead

36
Q

Dose of aspirin

A

Dose 75-300mg per day

37
Q

Dose of clopidogrel

A

Dose 75mg per day

38
Q

Warfarin final comment for dentists

A

It is safe to perform extractions on warfarin
-provided INR is less than 4.0
All patients must have INR within 24hr of extraction (in stable patients 72h will be OK)
Near pt testing devices give accurate results but must have documented good quality control
People with metal heart valves must be on warfarin

39
Q

New non-warfarin oral anticoagulants name

A 
Several names:
-NOACs (new)
-DOACs (direct) etc.
DOAC recommended name
Rapidly > usage
40
Q

Four DOACs:

A

Rivaroxaban, Apixaban, Edoxaban (Xa inhibitors)
Dabigatran (Thrombin inhibitor)
All licensed for thromboprophylaxis after hip and knee surgery
May replace low molecular weight heparin for general thromboprophylaxis
Also licensed in treatment of thrombosis and atrial fibrillation

41
Q

What are DOACs for

A

For prevention and treatment of thrombosis

Aiming to replace warfarin

42
Q

Pros of DOACs

A 
Standard oral doses, not weight based
No monitoring
No alcohol or food interactions
Fewer drug interactions 
No major adverse events other than bleeding
Half life 6-15 hours
Dabigatran mainly renally excreted
43
Q

Cons of DOACs

A 
No antidote (exc for dabigatran)
More expensive than warfarin
44
Q

DOACs and dental surgery

A

Use local anaesthetic with vasoconstrictor unless contraindicated
Use infiltration or intraligamentary injection if possible
If inferior alveolar nerve block is used, the injection should be administered slowly using an aspirating technique
If pt is on short term oral anticoagulant treatment, if possible delay the dental work until discontinuation of anticoagulation

45
Q

If dental extraction/ dental surgery require on oral anticoagulants

A

Do not take the anticoagulant on the morning of the dental work
Restart 3 hours post procedure

46
Q

Apixaban/ Dabigatran

  • usual drug schedule
  • morning dose (pre-treatment)
  • post-treatment dose
A

Twice a day
Miss morning dose
Usual time n evening
-as long as no ealier than 4 hours after haemostasis has been achieved

47
Q

Rivaroxaban or edoxaban

  • usual drug schedule
  • morning dose (pre-treatment)
  • post-treatment dose
A

Once a day; morning
-delay morning dose
-4 hours after haemostasis has been achieved
Once a day; evening
-not applicable
-usual time in evening as long as no earlier than 4 hours after haemostasis has been achieved

48
Q

Types of venous thrombosis

  • common
  • rare
A 
Common
-DVT
-PE
Rare
-cerebral vein thrombosis
-mesenteric vein thrombosis
-portal vein thrombosis
49
Q

Heritable risk factors for venous thrombosis

A 
Antithrombin deficiency
Protein C deficiency
Factor V Ledien
Protein S deficiency
Prothrombin 20210 A
50
Q

Acquired risk factors for venous thrombosis

A 
Age
Previous VTE
Antiphospholipid syndrome
Paralysis/ immobility
Major trauma/ surgery
Malignancy
Pregnancy
Chemotherapy
HRT
COCP
Obesity
51
Q

Mixed risk factors for venous thrombosis

A

Raised FVIII
Raised FIX
Raised XI
Raised fibrinogen

52
Q

VTE treatment options

  • acute
  • long-term
A 
Acute
-anticoagulation
-thrombolysis
-thombectomy
-inferior vena cava filter
Long-term
-anticoagulation
-stockings
53
Q

Duration of VTE treatment

A

3 months after provoked event
Long term after 2nd idiopathic thrombosis
Long term after 1st major PE
Consider long term after 1st idiopathic thombosis depending on risk factors for recurrence and bleeding

Haematological disease (Den 303) (6 decks)

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