coagulation disorders Flashcards
why do you need to know about the anticoagulants or platelets disorders that someone has as a dentist?
if they have a clotting disorder and are not on medications, they might bleed to death
those on anticoagulants require tx planning to prevent bleeding risks
what are safe dental procedures that do not require patients to alter their anticoagulant schedule?
o hygiene therapy
o pros
o restorative
o crowns
o bridges
o endodontics
o orthodontics
what are risky procedures that dentists need to consider for patients on anticoagulants?
minor oral surgery
extractions
perio surgery
implants
biopsies
3 types of antithrombocytic medication
1injectable anticoagulants
2 oral anticoagulants
3 antiplatelets
what is unfractionated heparin and when is it used
it is an injectable anticoagulant
- rapid control
- temporary, only active for a few minutes
- used for operations, not practical in dental setting
what is low moledular weight heparin and when is it used?
it is a type of injectable anticoagulant
injected once daily
does not interfere with dental tx
stops low level excess clotting without increasing bleeding risk
used for short term hypercoagulability, eg when first starting on warfarin
who needs to take anticoagulants
form blood clots too easily
pros valves
thrombophillia
atrial fib
DVT
heart valve disease
most common anticoagulants
- warfarin
- apixaban
- dabigatran (direct thrombin inhibitor)
- rivaroxaban
eg of a coumarin and a non coumarin
coumarin = warfarin
non coumarin = apixaban
what factor does apixaban inhibit
factor x (10)
what factor does warfarin inhibit
it is a vitamin k antagonist
inhibits protein c and s
inhibits production of vitamin k dependent clotting factors 2 7 9 10
why do you need to take heparin when you first start taking warfarin?
- initial hypercoagulability due to protein c and s inhibition
what is the acceptable range of INR for warfarin patietns
INR 2- 4
checked every 4-8 weeks for stability
what can INR be upset by
drug interactions and food
- warfarin is heavily bound to plasma proteins, other drugs can displace warfarin from the protein
- anyone taking warfarin has to take caution with other drugs
as a dentist what precautions do you need to take for warfarin patients
drug interactions
local haemostatic measures
check INR within 72 hours of a RISKY procedure
emergency out of hours contact
what drugs interact with warfarin
assume all drugs interact with warfarin but mainly
nsaids
aspirin
azole antifungals
what are the hazards of taking warfarin?
- haemorrhage during treatment
- trauma causing serious bleed
- soft tissue injury leading to bleeding into muscles
- rapid reversal of anticoagulation with vitamin k injection in hospital
what is the benefits of DOAC over warfarin
DOAC has predictable bioavailability so it doesnt require INR testing
it has rapid onset and short duration of action, effects lost within a day
what do you as a dental professional need to know when treating patients on doac
- low risk procedures do not require changing dose of NOAC
- high risk procedures can delay the morning dose of NOAC, then restart dose after treatment
- IDB if needed
- local haemostatic measures
- keep for 20min post extraction to assess bleeding
what drugs interact with doac?
nsaids
carbamazepine
macrolides
erythromycin
clarithromycin
most common antiplatelet drugs
- aspirin 75mg
- clopidogrel
- dipyridamole
when must you NOT stop antiplatelet drugs?
- CANNOT STOP in patients with coronary artery stent
antiplatelets vs anticoagulants
antiplatelets - inhibits platelet aggregation
anticoagulants - inhibits factors in the coagulation cascade
which drugs interact with antiplatelets?
- NSAIDs
- Carbamazepine
- Omeprazole
additionally, clopidogrel interacts with erythromycin and fluconazole
as a dentist, do you need to stop patients who are taking aspirin before their procedure?
if aspirin alone , no need to stop
if taking aspirin with another antiplatelet, need to expect prolonged bleeding and local haemostatic measures essential + Good post operative instructions with emergency contact details
what is an inherited bleeding disorder?
acquired defect that affects the coagulation of the blood
haemophillia vs thrombophillia
Haemophilia = too little clot formed
Thrombophilia = too much clot formed
haemophilia A and B affect which chromosome
X chromosome
therfore it is sex linked recessive
is haemophillia recessive or dominant
haemophillia a and b = sex linked recessive
von Willebrand = autosomal dominant
which chromosome does von willebrand affect
NOT x chromsome, just autosomal
haemophillia A is a deficiency of which factor?
factor 8
haemophillia B is a deficiency of which factor?
factor 9
von WIllebrand is a deficiency of which factor?
factor 8 deficiency +
reduced platelet +
Deficiency of von Willebrand factor
what are coagulation factor inhibitors
- Are antibodies
- That develop after you give treatment ie give factor 8 and 9
- More treatment, more frequent => higher levels of antibodies=> next dose has to be higher than the previous to overcome the inhibitors
DDAVP drug function
- aka desmopressin
- releases factor 8 that is bound to endothelial cells into the circulation
when is DDAVP used?
- used in mild haem a and severe von Willebrand to increase factor 8 in circulation
- cannot be used in haemophilia b because there is no factor 9 bound to the endothelial cells
Tranexamic acid function and when is it used
function = inhibitor of fibrinolysis, keeps any clots that are formed
used when = mild von willebrand and mild haem a
treatment for haem a
Severe and moderate – recombinant factor 8
Mild and carriers –
DDAVP and oral tranexamic acid
treatment for haem b
Severe and moderate – recombinant factor 9
Mild and carriers – recombinant factor 9
treatment for von willebrand
Severe and moderate – DDAVP
Mild and carriers –
oral tranexamic acid
which bleeding disorder is quite common but most people do not know
von Willbrand
How is haemophillia related to the dental profession?
- Non bleeding procedures done in primary care
- Risky procedure done in haemophilia centres/hospital
what is considered dangerous local anesthetic for hemophilia patients
1 IDB
2 lingual infiltration
3 posterior superior nerve block
for extractions done on haemophillia patients, what is the post operative instructions
severe - observed overnight in haemophillia unit
mild - observed for 2-3h after surgery + comprehensive post operative instructions + emergency contact
how does thrombophilia occur
- Clot formation > clot breakdown
- Excessive stable clot in circulation
causes of thrombophillia
- Can be acquired condition superimposed on a genetic tendency
o Acquired hypercoagulation
o Oral contraceptives
o Surgery
o Trauma
o Cancer
o Pregnancy - Could be a problem with fibrinolysis
- Could have reduced inhibitors so more clot than normal
o Protein c and s deficiency
o Antithrombin III deficiency
what deficiency can result in thrombophillia
o Protein c and s deficiency
o Antithrombin III deficiency
what could happen if you have untreated thrombophillia
Clot can embolise and lead to blockage of major blood vessels in the heart and/or lungs
(Pulmonary thromboembolism)
3 types of platelet disorders
Thrombocytopenia
Thrombocythemia
Qualitative disorder
Thrombocytopenia vs Thrombocythemia
Thrombocytopenia = too little
Thrombocythemia = too many platelets
penia = reduced
causes of thrombocytopenia
- Idiopathic
- Drug related
- Alcohol
- Penicillin
- Heparin
- Leukaemia
- Myelodysplasia
- Bone marrow producing excessive numbers of red and white cells with no capacity to make platelets
are the platelet function normal in thrombocytopenia and thrmbocythemia?
in thrombocytopenia, normal
in thrombocythemia, poor function
what is Qualitative platelet disorder
Normal platelets numberbut Abnormal function
causes of qualitative platelet disorders?
- Inherited
- Acquired
o Cirrhosis
o Drugs
o Alcohol
o cabg
