Abnormal bleeding and warfarin Flashcards
What dentistry procedures are associated with bleeding?
- Extractions
- Surgery, biopsies and trauma
- Periodontal therapy (probing too)
- Exposure of vital pulp
- Spontaneous (local and systemic causes)
What are the effects of blood loss?
- Patient distress
- Blood in tissues
- Blood in stomach (vomiting)
- Blood in airway (obstruction)
- Hypovolaemia - reduced blood volume - shock low BP
- Reduced oxygen carrying capacity (Hb decreased)
- reduced protein (water holding, clotting)
- Reduced platelets (less capacity to arrest haemorrhage)
How do we prepare for bleeding?
- Manage patient expectations - tell patient of risks
- Check bleeding/clotting risks
- Careful surgical technique - being as conservative as possible, least amount of extractions at a time
- Local measures - pressure, suture, surgicel, patience
How does bleeding reduce with Virchow’s triad in mind?
Pressure - stops blood flow
Suture - secures clot in place and holds surgicel
How does surgicel work?
It is foreign so activates the clotting cascade
What are the mechanisms of haemostasis?
- Vascular spasm
- Platelet plug
- Blood coagulation via extrinsic and intrinsic pathway
- Growth of fibrous tissue in the hole in the vessel permanently by fibroblasts
How does a platelet plug form?
Platelet adhesion - platelets adhere to exposed collagen
Release of thromboxane A2 causes increased stickiness
This causes nearby platelets to adhere to platelet plug which activates coagulation cascade by activation of factor X and prothrombin.
What would aspirin and clopidogrel be prescribed for?
They are common anti-platelets prescribed for ischaemic heart disease/recent strokes.
How does aspirin work?
Irreversibly - it effects all platelets you have and doesn’t wear off. To reverse it needs all the platelets to die off - weeks to occur.
It binds to platelet COX (cyclooxygenase) required for thromboxane A2 mediated aggregation.
Reduces chance of platelet plug
How does clopidogrel work?
Binds to the P2Y12 receptor irreversibly and prevents ADP mediated aggregation.
Reduces chance of platelet plug
Why would patients take anti-platelets?
- Vascular disease
- Ischaemic heart disease
- DVT
- Stroke
- Peripheral vascular disease
Should we stop aspirin for those needing extractions?
NO
Takes weeks for effect to be reversed, risk of stopping is greater than risk of strokes, ischaemia, peripheral heart disease
What triggers the intrinsic and extrinsic pathway?
Intrinsic - exposed collagen and platelet activation
Extrinsic - tissue damage
What happens at the final common pathway?
Activating factor X to factor Xa catalysing prothrombin to thrombin in which fibrinogen changes to fibrin.
What are tests of bleeding function?
-INR (international normalised ratio)- Patient’s prothrombin time/control prothrombin time, assessing warfarin anticoagulation
-Platelet count
- APTT (activated partial thromboplastin time) - assesses heparin anticoagulation
- Bleeding time (direct cut - rarely used)
Why would a patient be on warfarin?
Atrial fibrillation
Heart valve abnormalities or replacement
Thromboembolic disease (DVT or pulmonary embolus)
Some other cardiac and vascular abnormalities including patients with ischaemic heart disease.
How does warfarin work?
- prevents action of vitamin K produced in the gut by bacteria
- vitamin K is required in the liver to produce factors II, VII, IX and X
- Warfarin prevents carboxylation of clotting factors
- clotting factor half lives vary up to 60hrs
- Changes to warfarin level can take 7 days
- Long delay when drug is stopped - 7 days
- Many antibiotics enhance effect of warfarin eg metronidazole - gut affected so can affect vitamin K can make pt more or less likely to form blood clots
What INR is safe to perform extraction?
4 or less
What should you ask a pt who takes warfarin?
- Get them to show you their orange book
- Why are they taking warfarin?
- What their prescriber wants their INR to be
- Every month what their INR was
When checking the INR when is safe to perform an extraction?
If their INR is stable, check INR 72 hrs before extraction
IF not check within 24 hours
When planning an extraction for a pt on warfarin when should it be?
Early in the week and early in the day so if the pt has problems they can get in touch.
Make sure you explain there is a risk of bleeding and what they should do if they notice any?
How many extractions can you do with patient on warfarin?
INR 2-3 consider one side at a time as many extractions you can do.
3 -4 - forceps extraction one quadrant at a time
Be careful with ID blocks on patients with warfarin - do articaine infiltration
What local measures do we use to keep a clot?
Surgicel
Suture
How long should we keep a patient after XLA?
- 15-20 mins and give them instructions and contact info if they notice bleeding
What is wrong with warfarin?
There are multiple interactions with drugs (antibiotics, carbomazepine, antifungals, St Johns wart)
Food interactions - cranberry juice
Who takes the new oral anticoagulants (DOAC’s)?
AF
Thromobembolic disease (DVT/PE)
Heart valve replacement
CVA/ strokes
What factors do DOAC’s work on?
Apixaban and rivaroxaban - 10-10a
Dabigatran - fibrinogen to fibrin
How do we manage patients on DOAC’s when extracting?
Check SDCEP guidelines, with DOAC’s taken twice a day we may consider emitting morning dose but in general we dont stop the medication.
With patients with coagulopathies what do you do in regards to extractions?
- Have you ever had any problems with bleeding/bruising any medications to thin the blood.
- Get in touch with haemotologist/GP
- Take blood tests beforehand - ask GP to check clotting factors, INR, APTT, platelet count
How do you promote a blood clot in these patients after XLA?
Get pt to bite down on gauze - slows blood flow and promotes clot
Surgicel - oxidised cellulose and tranexamic acid - can stabilise blood clot in socket
Figure of 8 suture gives compression on gingivae
Oxidised cellulose - sheet of fabric that creates acidic environment that activates platelet and clotting cascade.
What are low risk bleeding procedures?
Simple extractions (1-3 teeth, with restricted wound size)
Incision and drainage of intra oral swellings
Detailed 6ppc
RSD
Direct or indirect restorations with subgingival margins
What are high risk bleeding procedures?
Complex extractions, adjacent extractions that will cause a large wound or more than 3 extractions at once.
Flap raising procedures:
- Periodontal surgery
- Elective surgical extractions
- Preprosthetic surgery
- Periradicular surgery
- Crown lengthening
- Dental implants
- Gingival recontouring
When should we not interrupt anticoagulant or antiplatelet therapy for?
- Patients with prosthetic metal heart valves or coronary stents
- Patients who have had a pulmonary embolism or DVT in the last 3 months
- Patients on anticoagulant therapy for cardioversion
What should we do for all patients taking anticoagulants/antiplatelets requiring dental treatment likely to cause bleeding?
- Plan treatment for early in the day/week
- Provide pre-treatment instructions
- Treat atraumatically as possible, use local measures and discharge when haemostasis is complete
- If travel time to emergency care is concern emphasise the use of measures to avoid complications
- Provide patient with post treatment advice and contact details for emergency
What do you advise a patient to do for a higher risk of bleeding complication who is taking apixaban or dabigatran?
- They will be taking this 2x a day, miss morning dose but take the usual one same time in the evening.
What do you advise a patient who is taking rivaroxaban or edoxaban?
1x a day
If they take it in the morning - delay morning dose until 4 hours after haemostasis has been achieved
If they take it in the night - take it as usual
