Anticoagulants And Antiplatelets

Question 1

What is primary haemostasis?

Answer 1

Damage to blood vessels from injury or invasive procedures causes platelets to be activated locally, resulting in an increased tendency to adhere to each other and damage endothelium.

Question 2

What is secondary haemostasis?

Answer 2

At the same time as platelet adherence, a cascade of reactions is initiated converting the inactive coagulation factors to their active forms (fibrinogen to fibrin).
Fibrin stabilises the primary platelet plug by cross linking platelets to each other and to the damaged blood vessel wall to prevent further loss of blood.

Question 3

Which stage of coagulation does anti platelet drugs have an effect on?

Answer 3

Anti-platelets interfere with platelet aggregation by reversibly or irreversibly inhibiting various steps in platelet activation required for primary hemostasis

Question 4

Which stage of the coagulation process do anticoagulants have their effect on?

Answer 4

Anticoagulants inhibit the production or activity of factors required for coagulation cascade- therefore impair secondary haemostasis

Question 5

What are some reasons a pt may be on anti platelets/ anticoagulants? And why?

Answer 5

Cardiac conditions, history of stroke
Following surgical procedures eg. Valve replacements, cardiac stents, joint replacements

To reduce the risk of developing a blood clot (thrombus) which can then travel through the body (embolus) causing hart attack/ stroke

Question 6

What are patients on anti platelets/ anticoagulants at risk of?

Answer 6

Increased bleeding risk

Question 7

What is warfarin?

Answer 7

A vitamin K antagonist
Inhibits vitamin K dependant modification of prothrombin and other coagulation factors which is required for normal function.

Question 8

What are some examples of dental procedures unlikely to cause bleeding?

Answer 8

LA by infiltration/ block
BPE
Supragingival PMPR
Direct or indirect restorations with supragingival margins
Impressions
Endo

Question 9

What are examples of dental procedures likely to cause bleeding with low risk of post op bleeding?

Answer 9

Simple extractions (1-3 teeth)
Incision and drainage of Intra oral swellings
6PPC
RSD
Direct or indirect restorations with sub gingival margins

Question 10

What are examples of dental procedures likely to cause bleeding with higher risk of post op bleeding complications?

Answer 10

Complex extractions
Flap raising procedures
Gingival recontouring
Biopsies

Question 11

How should the risk of bleeding/ clot formation be minimised when giving LA?

Answer 11

deliver LA using aspirating syringe, include vasoconstrictor.

Question 12

Can you give a pt on warfarin an ID block?

Answer 12

If indications pt has unstable INR, an INR should be requested and <4 before proceeding

Question 13

What are some medical conditions associated with an increased bleeding risk?

Answer 13

Renal
Liver disease
Heart failure
Coagulation disorders (haemophilia and Von willebrands)
Platelet disorders (thrombocytopenia)
Connective tissue disorders
Chemotherapy/ radiotherapy

Question 14

How do you assess a patients bleeding risk?

Answer 14

Assess whether dental treatment is likely to cause post op bleeding complications
MH- ask about use of anti platelets/ anticoagulants and other medications pt is on, bleeding history

Question 15

What is the bleeding risk for patients taking aspirin?

Answer 15

Aspirin alone- unlikely to have higher bleeding risk than non-coagulated patients

Question 16

What is the main difference between warfarin and DOACs

Answer 16

DOACs have a rapid onset (1-4 hours) and relatively short half lives

Question 17

Which DOACs are taken twice a day, and which DOACs are taken only in the morning?

Answer 17

Apixiban and dabigatran are taken twice a day
Rivaroxaban and endosaban are taken once a day (usually morning).

Question 18

What is the recommendation for patients on DOACs and high risk bleeding procedures

Answer 18

Miss morning dose (apixiban and rivaroxiban) or delay morning dose until 4 hours post haemostasis (rivaroxiban and endoxaban)

Question 19

What is the recommendation for patients on DOACs and low risk bleeding procedures

Answer 19

No need to interrupt drug
Plan treatment early in day (to allow for monitoring/ complications)
Limit initial treatment area (eg single tooth extraction)
Use local homeostatic measures (suture and packing, LA with vasoconstrictor)

Question 20

What is INR test and when is it used in dentistry?

Answer 20

International ratio test - measures the time taken for a clot to form in a blood sample, relative to a standard (INR 1)
Check pts INR when taking warfarin 24 hours before treatment (high or low risk bleeding) - should be <4

Question 21

What is the most commonly encountered anti platelet combination?

Answer 21

Aspirin and clopidogrel (ACS)

Question 22

What is the guidance for patients on anti platelets?

Answer 22

For procedures with low or high risk bleeding complications:
Limit initial treatment area
Carry out treatment in staged manner
Local homeostatic agents

Bleeding may be prolonged in dual therapy

Question 23

What is the guidance for patients on anticoagulants and anti platelets combinations?

Answer 23

Consult with patients prescribing clinician to assess the likely impact of the particular drug combination and their bleeding risk

Some patients only on this for 3-4 weeks so possible to delay dental treatment