Coagulation Disorders Flashcards
What are classes of injectable anticoagulatant?
what are the two types
herparin
Unfractionated Heparin - rapid acting, inhibits antithrombin 3, used mainly in hospitals
Low Molecular Weight Heparin - longer acting, given subcutaneously daily
What are the two classes of oral anticoagulation?
courmarin, non-coumarin based
What are examples of antiplatelet medication?
aspirin/clopidogrel, new drugs
Why is aspirin taken in combination with some antiplatelets?
to reduce function/adhesion of platelets
What are dental (general) preventaive measures that reduce bleeding procedures?
*Regular dental care
*Dietary advice
*Oral Hygiene
*Fluoride supplements
*Fissure sealant
What are safe dental preocedures for all drugs?
*Hygiene therapy
*Removable Prosthodontics
*Restorative dentistry, including crowns and bridges.
*Endodontics
*Orthodontic treatment
What are dental procedures that require caution?
- Extractions
- Minor oral surgery
- Implants
- Periodontal surgery
- Biopsies - sometimes
What are medical indications for anticoagulation drugs for life?
Conditions where blood clots will form too readily on or in the circulation
Atrial fibrillation
Deep venous thrombosis
Heart valve disease and Mechanical heart valves
Thrombophilia
ask patient about medications
How does warfarin work?
vitamin k antagonist
Slow onset over THREE days
Initial HYPERCOAGULABILITY (therefore use heparin) due to protein C & S inhibition first
Inhibits production of Vitamin K dependent clotting factors 2, 7, 9, 10
What are the vitamin k dependant clotting factors that warfarin inhibits?
what factors cause the hypercoagulation state
2, 7, 9 10
What is the warfarin response measured using?
INR
prothrombin > thrombin
What is the normal INR for someone on warfarin?
2-4
When would the value of INR be raised in a patient on warfarin?
3-4 in prosthetic valves and higher risk of DVT
How often should the INR be cheked?
every 4-8 weeks
What should be done for a patient on warfarin awaiting dental procedures likely to cause haemorrhage?
INR & FBC blood test within 72 hours of treatment
What are examples of local haemastatic measures?
cellulose sponge/gauze
sutures
LA
What medications should not be prescribed for dental patients on warfarin?
Aspirin (as an analgesic)
NSAIDs including Ibuprofen, Diclofenac
Azole antifungal drugs
Fluconazole
Itraconazole
Miconazole
What are the hazards of taking warfain and how is it treated?
haemorrhage
* Usually this is from TRAUMA such as hip/bone fracture
following a fall
* Soft tissue injury leading to bleeding into muscles
* RAPID reversal of anticoagulation with Vitamin K injection possible – only in a hospital setting
Advantages VS Disadvantages of NOACs?
Advantages
* No need to monitor action – predictable bioavailability
* Rapid onset of action – within an hour of dose
* Reduced interactions with food/drugs
Disadvantages
* Short duration of action, may only be used for short treatments
How do NOAC work?
act by preventing the effect of factor X
How should you treat someone on NOAC?
high/low procedure?
- Treat early in the day. Limit initial treatment
- LOW risk procedure – no NOAC change
- HIGHER risk procedure – miss/delay morning dose
What are the NOAC interations?
Avoid macrolide antibiotics (Erythromycin and Clarithromycin)
Avoid NSAID
What do antiplatelet drugs do?
§Inhibit platelet aggregation
§Inhibit thrombus formation in the arterial circulation
§Often used in combination
What is very important when patient is on antiplatelet drugs?
§VERY important not to stop drug if patient has coronary artery stent in place
How should you treat someone on aspirin therapy alone?
- Treat without interrupting medication
- Local haemostatic measures
- Consider limiting initial treatment area
How should you treat someone on non-aspirin single therapy & dual therapy WITH aspirin?
- Do not interrupt treatment
- Expect prolonged bleeding – limit initial area
- Local Haemostasis essential
How should you treat someone on two antiplatelet drugs in combination without aspirin?
- Discuss with Doctor stop one of the drugs 7 days prior to surgery
- If this is not possible refer to a hospital unit
- Local measures to aid haemostasis
- Good post operative instructions
- Must include emergency contact details
What are the interations antiplatelets may have?
Avoid additional NSAIDs where possible
Carbamazepine and Omeprazole may reduce the efficacy of the Antiplatelet drugs.
What might inherited bleeding disorders affect?
COAGULATION CASCADE
* A reduction or in one, or more, of the coagulation factors or control proteins
* Too LITTLE clot formed – Haemophilia
* Too MUCH clot formed - Thrombophilia
PLATELETS
* Number
* Function
A COMBINED DEFICIENCY
What are disorders reducing coagulation factors and what factor do they affect?
Factor VIII deficiency - Haemophilia / Haemophilia A
Factor IX deficiency - Christmas disease / Haemophilia B
Vonwillebrand Disease -Reduced factor VIII level and platelet aggregation
Factor XI (Haemophilia C) deficiency - Common in the Ashkenazy Jew population
How is haemophilia a and b inherited?
Inheritance - Sex-linked recessive
* defective gene on the X chromosome
* Males are affected and females are carriers
How is the severity of haemophilia A managed?
severe/moderate VS mild
Severity of disease depends upon the amount of factor produced
Severe and moderate: factor 8 replacement therapy
Mild: DDAVP (desmopressin) or antifibrinolytic agents like tranexamic acid.
DDAVP VS Transexamic acid
desmopressin – releases factor VIII that has been bound to endothelial cells giving a temporary boost to Factor VII levels and clotting ability
tranexamic acid - inhibitor of fibrinolysis (keeps any clot that is formed)
How is severe and moderate haemophilia B managed VS how is mild haemophilia B managed?
both require the use of (replacement therapy) recombinant factor IX
What are coagulation factor inhibtors?
development of coagulation factor inhibitors (antibodies against factors VIII and IX) as a complication of treatment (reduce treatment episodes)
What type of disease is vone willebrand’s disease?
Autosomal dominant – NOT transmitted by the X chromosome
* Both sexes equally affected
* Deficiency of von Willebrand factor
* reduction in factor VIII levels
* Most prevalant in UK
How is severe and moderate von willebrand’s disease managed VS mild/carrier ?
severe/moderate: DDAVP enough for most
mild: oral tranexamic acid
Why is management of rarer bleeding disorders complex?
bleeding does not always relate to the factor levels
Where is severe and moderate VS mild haemophilia treated in dental care?
Severe/Moderate: dental treatment unit attached to the Haemophilia centre. prosthodontics and other no-risk treatments can be in primary care.
Mild: GDP. patient reviewed at haemophilia centre every 2 years
What are the 5 dental procedures that require care in hameophilic patients?
- Administration of local anaesthesia
- Extractions
- Minor oral surgery
- Periodontal surgery
- Biopsies
What types of LA are safe in haemophilia?
- Buccal infiltration
- Intraligamentary injections
- Intra-papillary injections
What types of LA are dangerous in haemophilic patients?
- Inferior alveolar nerve block
- Lingual infiltration
- Posterior Superior nerve block
How should extractions/ surgeries be taken for severe VS mild haemophilic patients
severe: patients should be observed overnight following surgery.
mild: patients observed 2-3 hours after surgery
What is thrombophilia and how does it happen?
Increased risk of clots developing
Often an acquired condition superimposed on a genetic tendency
* Can present any point in life
What happens if the clot embolises in throbophilia?
can lead to blockage of major blood vessels in the heart and/or lungs
* pulmonary thromboembolism
* Life threatening in many cases
What are the inherited hypercoagulation syndromes?
- Protein C deficiency
- Protein S deficiency
- Factor V Leiden
- Antithrombin III deficiency
What are the aquired hypecoagulation syndromes?
- Antiphospholipid syndrome (Lupus anticoagulants)
- Oral contraceptives
- Surgery
- Trauma
- Cancer
- Pregnancy
- Immobilisation
What is reduced platelet numbers called?
thrombocytopenia
What is increased platelet numbers called?
thrombocythemia
platelets do not work despite increase
What are the causes of thrombocytopenia?
Idiopathic (unknown cause)
Drug related Alcohol
Penicillin based drugs Heparin
Secondary to lymphoproliferative disorder - leukaemia or myelodysplasia
What are patients with throbocythemia usually on?
aspirin to prevent clot formation
What are examples of inherited qualitative diseases?
platelets are normal in number, but abnormal in function
Bernard Soulier Syndrome
Hermansky Pudlak
Glanzmann’s thrombasthenia
What are examples of acquired qualitative diseases?
platelets are normal in number, but abnormal in function
Associated with liver cirrhosis
Caused by certain drugs
Caused by alcohol use
Occurring after cardiopulmonary bypass procedures
When is special care taken for patients with platelet disorders?
platelet count and dental procedures
If the Platelet count is:
* BELOW 100x109/L - primary care treatment
* BELOW 50x109/L – hospital treatment
* above 500 x 109/L – either hospital or primary care setting
above 100x109 is normal - precaution
SPECIAL CARE is REQUIRED for:
* Extractions
* Minor oral surgery
* Periodontal surgery
* Biopsies
