Thrombophilia and Acquired Anticoagulation Flashcards
thrombophillia
Increased risk of clots developing
- Clot excessively
When clots break off, embolise in blood stream, block of chambers in heart and vessels in lungs
Often an acquired condition superimposed on a genetic condition
Can be inherited or acquired
Usually possible to find a cause for the clot
4 inherited syndromes of thrombophillia
- Protein C deficiency
- Protein S deficiency
- Factor V Leiden
- Antithrombin III deficiency
May have abnormalities of these
- Maybe all slightly altered
Different reasons why might have but not necessarily fit into one
7 examples of acquired syndromes of thrombophillia
Antiphospholipid syndrome
- Lupus anticoagulants
Oral contraceptives
Surgery
- Bed bound makes surgery more likely to form clots
Trauma
- Exaggerated repair mode
Cancer
Pregnancy
Immobilisation
- Higher risk of blood clots, DVT, pulmonary embolism
3 types of platelet abnormalities
Thrombocytopenia
Qualitative disorders
Thrombocythemia
thrombocytopenia
Reduced platelet numbers
qualitative disorders
Normal platelet number but abnormal function
Thrombocythemia
increased number of platelets
uncommon
causes of thrombocytopenia
Idiopathic
Drug related Alcohol
- Penicillins
- Heparin
Secondary to lymphoproliferative disorder
issues of thrombocytopenia
too little - not OK not making enough
Dental treatment can proceed safely providing the platelet count > 50*10^9
3 rare causes of qualitative platelet disorder
Bernard Soulier Syndrome
Hermansky Pudlak
Glanzmann’s thrombasthenia
4 acquired causes of qualitative platelet disorder
Cirrhosis
Drugs
Alcohol
Cardiopulmonary bypass
what are thrombocythemia pt usually on
aspirin to prevent clot formation
3 common causes of liver disease
alcohol
hepatitis
drug induced
(sources of acquired bleeding)
haematological change in haemoglobin in liver disease
little change
haematological change in platelets in liver disease
decrease
stops blood initially before clot formed
haematological change in prothrombin time in liver disease
increase
fewer CF made
haematological change in APTT in liver disease
increase
haematological change in TT in liver disease
increase
increase in INR indicates
coagulopathy pt
- serious coagulation issue
effect on dental surgery of mild stage liver disease
blood results often normal so normal precautions apply
effect on dental surgery of moderate stage liver disease
often only one parameter abnormal and platelet count >100
no problem with tx
local measure following extraction
effect on dental surgery of severe stage liver disease
all blood results abnormal (platelets and INR)
problems with haemostasis
extraction must be carries out in conjunction with haematologist
3 anti-thrombotic medications
oral anticoagulation
heparins
anti-platelet medications
what do anti-thrombotic medications induce
drug induced coagulopathy
common cause of bleeding issue is medical Tx bot issue itself
advantage of oral anticoagulation and anti-platelet medication
swallow (not injection)
advantage and disadvantage of heparins
disadvantage: injection
advantage: very responsive
low molecular weight and normal types
5 indications for anticoagulation medications
Atrial fibrillation
Deep venous thrombosis
Heart valve disease
Mechanical heart valves
Thrombophilia
what is the deciding factor on anti-thrombotic medication choice
Onset and duration of Tx is deciding factor on method
Whilst stay in hospital post operation
- heparin for short term as not in community care so pills less efficient
Pills at home
- less likely to clot in atria
- less likely stroke in brain
- managed in community
3 types of oral anticoagulatns
coumarins (warfarin)
direct factor Xa inhibitors
- rivaroxaban
- apixaban (common in Ggow)
direct thrombin inhibitors
warfarin
Most used drug in the world for anticoagulation (coumarin)
Cheap
Process to put on and Monitoring is complicated
new oral anticoagulants NOAC
Rivaroxaban
Apixaban
Dabigatran
Increasing use as ‘safer’ and ‘cheaper’ alternative
No routine monitoring
- Always 50% bioavailability
- Easy to work out dose
- Constant
- – Warfarin bioavailability is unpredictable
not in hospital on heparin first – physicians, nurse
- Used in short term treatment
time established would need to stop if used warfarin
bioavailability
amount of drug doing work
advantages of NOAC
Increasing use as ‘safer’ and ‘cheaper’ alternative
No routine monitoring
- Always 50% bioavailability
- Easy to work out dose
- Constant
- – Warfarin bioavailability is unpredictable
not in hospital on heparin first – physicians, nurse
- Used in short term treatment
time established would need to stop if used warfarin
how is response measured for warfarin
INR
- checked every 4-8 weeks
- all pt should carry an anticoagulant booklet
daily dose between 1 and 15mg varies
what is the safe precaution to take with warfarin
Safest all drugs would interfere with warfarin
Test warfarin the day after starting new medication (24-48hrs)
- Less effect - increase dose
- More effect - lower dose
Always seek advice from GP if you are prescribing
- They need to do testing – rare to do at home
Antibiotic - get GP involved as need treatment next today
particular medications to use with caution in combination with warfarin
Aspirin (as an analgesic)
Most antibiotics
- Amoxycillin least likely to cause problems
Azole antifungal drugs
- Fluconazole
- Itraconazole
INR
internationalised normalised ratio
Prothrombin time ratio corrected for the warfarin sensitivity of the thromboplastin reagent
- Ratio between pt and control pt
If normal pt – should be 1
Bigger ratio – PT time of pt will increase??
INR = Patient PT/ Mean Normal PT (international sensitivity index)
INR =
Patient PT/ Mean Normal PT (international sensitivity index)
should be 1
target INR for mechanical heart valves
3.0-4.0
vary from person to person – depending on what you need to do
target INR recurrent VTE while adequately anti-coagulated
3.0-4.0
vary from person to person – depending on what you need to do
atrial fibrillation/other causes target INR
2.0-3.0
vary from person to person – depending on what you need to do
key warfarin risk
Haemorrhage (higher risk than if not on, greater trauma risk)
1% per annum risk of serious bleed (needing hospitalisation/transfusion)
- 25% of these are fatal
Issue in elderly – need to have operation, stroke
3 risks of adjusting INR
Fatal thromboembolic events
Non-fatal thromboembolic events
Rebound hypercoagulable state
- Restarting warfarin makes coagulation more likely
what does warfarin stop production of and needs replaced medically for correct coagulation
Use warfarin stop function of vitamin K
- Restore Clotting Factors to normal
- —-give pt vit K to overcome fact warfarin stop making vit K
Reverse effect of warfarin quickly
- No excess bleeding with trauma
4 treatments when INR must be checked
Extractions
Minor oral surgery
Periodontal surgery
biopsies
4 treatments where INR is not needed to be checked
Prosthodontics
Conservation
Endodontics
Hygiene phase therapy
(less risk of blood)
general recommendation regrading anaesthetics and warfarin
use LA containing a vasoconstrictor
- reduce blood flow to tissue, decrease bleeding issue
Where possible use an infiltration, intrafilamentary or mental nerve injection
If there is no alternative an inferior alveolar nerve block is used the injection should be administered slowing using an aspirating technique
- Very dangerous for haemophilia if give ID nerve block – don’t give
when should thrombophillia/coagulopathy pt be seen
in morning and early in the week
- still available in surgery in coming days if an issue
timing of INR check for treatment
INR must be checked in the 48 hours prior to treatment but should be as near as possible to time of treatment
INR value for treatment to proceed
<4.0
what is the maximum extraction for pt with thrombophillia/coagulopathy
3 teeth (roots) i.e. 3 incisors or 1 lower 6
4 local measures that can aid haemostasis
LA infiltration
oxidised cellulose
sutures
pressure
good post operative instructions (must inc emergency contact details)
2 types of heparins
unfractionated
low molecular weight
(less common that oral anticoagulants)
unfractionated heparins
Given by IV infusion in hospital – check APPT
- Drip stand with pump on it in hospital, not out in community
Very short half-life so very controllable
low molecular weight heparins
Given by subcutaneous injection by the pt at home
Once daily injection
Doesn’t bleed excessively – no issues
Dose weight related – no monitoring
3 drugs available for anti-platelet medications
Low dose aspirin (95mg daily)
Clopidogrel
Dipyridamole
guideline for single agent anti-platelet use
Delayed haemostasis but adequate haemostasis
guideline for dual agent anti-platelet use
usually aspirin and clopidogrel
If stent pt, discuss with cardiologist
Otherwise – stop one of the drugs 7 days prior to surgery (discuss with doctor)
Do not stop unless discuss with doctor first
what is the half life of platelts
7 days
takes 7 days for anti-platelet medication to leave system
